Geoinformation objects. Gis concept. GIS in Russia

GIS (DublGIS Barnaul)

It is rather difficult to give an unambiguous short definition of this phenomenon. Geographic Information System (GIS) - this is an opportunity for a new look at the world around us. If we dispense with generalizations and images, then GIS is a modern computer technology for mapping and analyzing objects in the real world, as well as events taking place on our planet. This technology combines traditional database operations such as query and statistical analysis with the full visualization and geographic (spatial) analysis benefits of a map. These capabilities distinguish GIS from other information systems and provide unique opportunities for its application in a wide range of tasks related to the analysis and forecast of phenomena and events of the surrounding world, with understanding and highlighting the main factors and causes, as well as their possible consequences, with planning strategic decisions and the current consequences of the actions taken. Mapping and geographic analysis are nothing entirely new. However, GIS technology provides a new, more modern, more efficient, convenient and quick approach to analyzing problems and solving problems facing humanity as a whole, and a specific organization or group of people in particular. It automates the analysis and forecasting procedure. Before the use of GIS, only a few had the art of generalizing and fully analyzing geographic information in order to make informed optimal decisions based on modern approaches and tools. GIS is now a multimillion dollar industry that involves hundreds of thousands of people around the world. GIS is studied in schools, colleges and universities. This technology is used in almost all spheres of human activity - whether it is the analysis of such global problems as overpopulation, pollution of the territory, the reduction of forest land, natural disasters, or the solution of particular tasks, such as finding the best route between points, choosing the optimal location for a new office, searching at home at his address, laying a pipeline on the ground, various municipal tasks. According to the territorial coverage, there are global GIS (global GIS), subcontinental GIS, national GIS, often having the status of state, regional GIS (regional GIS), subregional GIS and local, or local GIS (local GIS).

GIS differ in the subject area of \u200b\u200binformation modeling, for example, urban GIS, or municipal GIS, MGIS (urban GIS), environmental GIS (environmental GIS), etc .; among them, land information systems received a special name, as especially widespread. The problem orientation of a GIS is determined by the tasks solved in it (scientific and applied), among them the inventory of resources (including the cadastre), analysis, assessment, monitoring, management and planning, decision support. Integrated GIS, IGIS (integrated GIS, IGIS) combine the functionality of GIS and digital image processing systems (remote sensing data) in a single integrated environment.

Multiscale GIS is based on multiple or multiscale representation of spatial objects, providing graphical or cartographic reproduction of data at any selected level of a scale series based on a single dataset with the highest spatial resolution ... Spatio-temporal GIS (spatio-temporal GIS) operate on spatio-temporal data. Implementation of geographic information projects (GIS project), creation of GIS in the broad sense of the word, includes the following stages: feasibility study, including the study of user requirements and functional capabilities of the used GIS software, feasibility study, assessment of the ratio Costs / benefits; system design GIS (GIS designing), including the stage of a pilot project (pilot-project), development of GIS (GIS development); testing it on a small territorial fragment, or test area, prototyping, or creating a prototype, or prototype; GIS implementation; operation and use. The scientific, technical, technological and applied aspects of the design, creation and use of GIS are studied by geoinformatics.

GIS history

Initial period (late 1950s - early 1970s)

Research of fundamental possibilities, border areas of knowledge and technologies, development of empirical experience, first large projects and theoretical works.

• The advent of electronic computers (ECM) in the 50s.
• The advent of digitizers, plotters, graphic displays and other peripherals in the 60s.
• Creation of software algorithms and procedures for graphic display of information on displays and using plotters.
• Creation of formal methods of spatial analysis.
• Creation of software tools for database management.

The period of government initiatives (early 1970s - early 1980s)

Government support for GIS has stimulated the development of experimental work in the field of GIS based on the use of street network databases:

• Automated navigation systems.
• Waste and garbage collection systems.
• Vehicle traffic in emergencies, etc.

Period of commercial development (early 1980s - present)

A wide market for a variety of software tools, the development of desktop GIS, the expansion of their scope through integration with nonspatial databases, the emergence of network applications, the emergence of a significant number of non-professional users, systems that support individual datasets on separate computers open the way for systems that support corporate and distributed geodatabase.

User period (late 1980s - present)

Increased competition among commercial producers of geographic information technology services gives advantages to GIS users, the availability and "openness" of software tools makes it possible to use and even modify programs, the emergence of user "clubs", teleconferences, geographically separated, but connected by a single topic of user groups, an increased need for geodata, the beginning of the formation of the world geoinformation infrastructure.

How GIS works

GIS stores information about the real world as a collection of thematic layers that are grouped based on geographic location. This simple yet highly flexible approach has proven its value in a variety of real-world tasks: tracking the movement of vehicles and materials, detailed display of real-world situations and planned activities, and modeling global atmospheric circulation. Any geographic information contains information about the spatial position, whether it is a reference to geographic or other coordinates, or links to an address, postal code, constituency or census district, identifier of a land or forest area, road name, etc. When using such links, a procedure called geocoding is used to automatically determine the location or locations of an object (s). With its help, you can quickly determine and see on the map where the object or phenomenon of interest is located, such as the house where your friend lives or the organization you need is located, where an earthquake or flood occurred, which route is easier and faster to get to the point you need or at home.

Vector and raster models

GIS can work with two significantly different types of data - vector and raster. In a vector model, information about points, lines and polygons is encoded and stored as a set of X, Y coordinates. The location of a point (point object), such as a borehole, is described by a pair of coordinates (X, Y). Linear features such as roads, rivers, or pipelines are saved as X, Y coordinate sets. Polygon features, such as river catchments, land parcels, or service areas, are stored as a closed set of coordinates. The vector model is especially useful for describing discrete objects and is less suitable for describing continuously changing properties, such as soil types or the availability of objects. The raster model is optimal for working with continuous properties. A raster image is a set of values \u200b\u200bfor individual elementary components (cells), it is similar to a scanned map or picture. Both models have their own advantages and disadvantages. Modern GIS can work with both vector and raster models.

GIS layers

All cartographic information in a GIS is organized in layers. Layers are the very first level of abstraction in GIS. When working with GIS, we are obliged to divide our existing data into layers. Each layer contains objects of a certain type, united by common characteristics. Working in GIS, we can connect and disconnect layers of interest to us, or change the order of their display. Layers are of the following types:

Point

Point layers contain objects that can be abstracted to a point, such as a well or city. For the sake of clarity of understanding, even a city can be represented as a point.

Linear

These objects can be abstracted into polyline or smooth lines, such as rivers, roads, or pipelines.

Polygonal or areal

Objects of this type are presented as being within a certain polygon, for example, license areas.

Areal objects can consist of several contours. This is necessary if you want to represent a polygon with a hole inside. The figure shows an example of a regular polygon and a polygon consisting of two contours.

The last point of the polygon must always coincide with the first point. Whether this is correct or not, this is the way it is in geographic information systems. Thus, a polygon cannot have less than four points. If the polygon has zero area, that is, it degenerates, then it must be deleted. The polygon must also not have self-intersections. Such shortcomings can later lead to serious calculation errors and should therefore be avoided.

Images

Bitmap graphics linked to geographic coordinates, such as satellite images or scanned maps.

Mesh models

These are structure maps and parameter maps. Initially, these models were based on a rectangular grid with a Z (parameter) value specified at the grid points.

Now the structure of such models is often more complex, but traditionally they continue to be called grids or grids. Modern grids can contain rifts, refinement areas, or spline-based. The meaning of grid models remains the same: continuous representation of a parameter over a certain area.

A spline mesh differs from a regular mesh in that its surface is perfectly smooth, which is more natural for most models. Fault meshes contain additional segments to simulate an even fracture. In a conventional grid model, the gap is stepwise. Grid models are also called contour maps.

Special types of layers

These five types of layers are standard for any professional GIS, but in addition to them, there may be other, special types of data, due to the scope of this system. For example, these can be faults (for modeling meshes with faults), raster maps (for representing very large raster images), 3D models (for 3D reservoir models).

GIS data tables

Line points and polygons have attribute data tables for their features.

Each object on the map has a corresponding row in the data table. Using the data table, you can find and sort objects, highlight them on the map by attributes, or view the attributes of the selected objects. Attribute table allows you to search for objects, sort them, select by conditions, group, create filters, perform calculations. An attribute table turns a GIS into a database where you can perform data analysis or data management with advanced GIS tools. Without attribute tables, geographic information systems would not make sense, and maps in them would not be maps, but simply drawings, like drawings in CorelDraw or Paint.

Points in lines and polygons also have their own attribute tables. So, for example, seismic profiles can be loaded along with the data on the picked horizons and used to build maps in contours. The data table supports the concept of selected objects, such rows in the table are marked with a different color. Selected objects are also displayed in a slightly different way on the map. Object selection is very often used in data analysis. You can select objects both in the table and on the map, as well as according to the specified conditions.

Formation of layers

A very important topic is the correct formation of the layer structure. The usefulness of any database, including GIS, is highly dependent on the correct data structure. You can even state the following: the usefulness of the database is directly proportional to its correct organization and order in the data. If the data in the database contains a large number of errors or is improperly organized, then this can negate all the advantages of the database as such. For this reason, the ability to properly structure information is important. For example, if you load seismic data, then it would be correct to combine all seismic crews in one layer, and not create several layers by grouping them by regions or areas. It's better to stick to this rule: one data type - one table (or one layer). On the other hand, dissimilar objects are best placed in different layers, even if they are united by a common theme. Thus, it is better to divide roads and railways into two layers, and then place them in the "Traffic routes" group.

Coordinates

Everyone knows that the earth is round, and the map is flat, and the surface of the ball cannot be turned onto a plane without deformations. For this reason, projections are used in cartography. Poses are the rules and formulas for transforming one coordinate into another. Usually, a transformation is used from spherical (geographic) coordinates to rectangular coordinates (map coordinates). Projections are either equal-area or conformal, that is, they preserve the area of \u200b\u200bobjects or corners. Sometimes the projection can distort both, minimizing distortion in general. For our country, the standard system transformation is the coordinate system "42nd year". The "42nd Year" system divides the territory of the globe into 60 zones, 6 degrees each. The Tyumen region, for example, is located within the 12th, 13th and 14th zones. Year 42 is an equal area projection. GIS is designed so that it can store data in one coordinate system and display it in another. Therefore, it is necessary not to get confused with the coordinate system in which the data is stored and in which it is displayed on the map. To reduce confusion with projections, Isoline only supports two variants of the original data:

• Rectangular coordinates (any arbitrary coordinates to which no transformation is applied).
• Geographic coordinates (degrees, minutes, seconds, which, when displayed on the map, are converted into any projection).

Here are options for displaying the same plot in different coordinate systems and projections.

The projection is "polyconic". Real coordinates are degrees, displayed coordinates are degrees.

The projection is not installed. Real coordinates are "polyconic", displayed coordinates are rectangular.

The projection is not installed. Real coordinates are degrees, displayed coordinates are rectangular.

The projection is "polyconic". Real coordinates are "polyconic", displayed coordinates are rectangular.

As you can see from the pictures, the top two suit us perfectly, but the third and fourth are not. The third figure is actually quite correct, but the projection is not specified, and therefore we see the image "as is", in degrees. In the fourth figure, we tried to display a polygon, the data of which is not degrees, in a "polyconic" projection, and the system did not understand us. From this, we can draw the following conclusion: it is impossible to set a projection for rectangular coordinates, since in this case the transformation formulas are applied to them a second time, and the image is incorrect.

It is also necessary to take into account the fact that a straight line drawn in one coordinate system is not a straight line in another system, and the areas of objects may differ, even if the projections are equal.

Rectangular coordinates

"polyconic", without display correction.

Coordinate system Mollweide.

polyconic ", with display correction.

Therefore, if you need accurate line lengths, precise areas, and accurate display, then you need to use the special tools of the system.

The tasks that GIS solves

General-purpose GIS, among other things, usually performs five procedures (tasks) with data: input, manipulation, control, query and analysis, visualization.

Input

For use in GIS, the data must be converted to a suitable digital format. The process of converting data from paper maps into computer files is called digitization. In modern GIS, this process can be automated using scanner technology, which is especially important when carrying out large projects, or, with a small amount of work, data can be entered using a digitizer. Many data have already been translated into formats that are directly perceived by GIS packages.

Manipulation

Often, for a specific project, the existing data needs to be additionally modified in accordance with the requirements of your system. For example, geographic information can be at different scales (street centerlines are at a scale of 1: 100,000, census district boundaries are at a scale of 1: 50,000, and residential properties are at a scale of 1: 10,000). For joint processing and visualization, it is more convenient to present all data on a single scale. GIS technology provides different ways to manipulate spatial data and highlight the data needed for a specific task.

Control

In small projects, geographic information can be stored as regular files. But with an increase in the amount of information and an increase in the number of users for storing, structuring and managing data, it is more efficient to use database management systems (DBMS), then special computer tools for working with integrated data sets (databases). In GIS, it is most convenient to use a relational structure in which data is stored in tabular form. In this case, common fields are used to link tables. This simple approach is flexible enough and is widely used in many GIS and non-GIS applications.

Query and Analysis

If you have GIS and geographic information, you can get answers to simple questions (Who is the owner of this land plot? At what distance are these objects from each other? Where is this industrial zone located?) And more complex queries that require additional analysis (Where are places for construction new house? What is the main soil type under the spruce forests? How will the construction of a new road affect traffic?). Queries can be set both by a simple mouse click on a specific object, and with the help of advanced analytical tools. With the help of GIS, one can identify and set patterns for search, play scenarios like “what will happen if…”. Modern GIS has many powerful analysis tools, of which two are the most significant: proximity analysis and overlay analysis. To analyze the proximity of objects relative to each other, GIS uses a process called buffering. It helps answer questions like: How many houses are within 100 meters of this body of water? How many customers live within 1 km of this store? What is the share of oil produced from wells located within 10 km from the management building of this NGDU? The overlay process involves the integration of data located in different thematic layers. In the simplest case, this is a display operation, but in a number of analytical operations, data from different layers are physically combined. Overlay, or spatial aggregation, lets you, for example, integrate soil, slope, vegetation, and tenure data with land tax rates.

Visualization

For many types of spatial operations, the end result is a map or graph of the data. A map is a very efficient and informative way of storing, presenting and communicating geographic (georeferenced) information. Previously, maps were created for centuries. GIS provides amazing new tools that expand and develop the art and scientific foundations of cartography. With its help, the visualization of the maps themselves can be easily supplemented with reporting documents, three-dimensional images, graphs and tables, photographs and other means, for example, multimedia.

GIS-related technologies

GIS is closely related to a number of other types of information systems. Its main difference lies in the ability to manipulate and analyze spatial data. Although there is no universally accepted classification of information systems, the description below should help distance GIS from desktop mapping systems, CAD systems, remote sensing, database management systems (DBMS or DBMS) and technology. global positioning (GPS).

Desktop mapping systems use cartographic representation to organize user interaction with data. In such systems, everything is based on maps, the map is a database. Most desktop mapping systems have limited data management, spatial analysis, and customization capabilities. The corresponding packages work on desktop computers - PCs, Macintosh and lower-end UNIX workstations.

CAD systems

CAD systems capable of project drawings and plans of buildings and infrastructure. To combine into a single structure, they use a set of components with fixed parameters. They are based on a small number of rules for combining components and have very limited analytical functions. Some CAD systems are extended to support cartographic data representation, but, as a rule, the utilities available in them do not allow you to efficiently manage and analyze large spatial databases.

Remote sensing and GPS

Remote sensing techniques are an art and scientific trend for taking measurements of the earth's surface using sensors such as various cameras on board aircraft, global positioning system receivers or other devices. These sensors collect data in the form of images and provide specialized capabilities for processing, analyzing and visualizing captured images. Due to the lack of sufficiently powerful data management and analysis tools, the corresponding systems can hardly be attributed to real GIS.

Database management systems are designed to store and manage all types of data, including geographic (spatial) data. DBMSs are optimized for such tasks, so many GIS have built-in DBMS support. These systems do not have GIS-like analysis and visualization tools.

What GIS can do for you

Make spatial queries and analyze

GIS's ability to search databases and perform spatial queries has saved many companies millions of dollars. GIS helps to reduce the time to receive answers to customer inquiries; identify areas suitable for the required activities; identify the relationship between different parameters (for example, soils, climate and crop yields); identify places of power grids. Realtors use GIS to find, for example, all houses in a given area that have slate roofs, three rooms and 10-meter kitchens, and then provide a more detailed description of those buildings. The request can be refined by introducing additional parameters, for example, cost parameters. You can get a list of all houses located at a certain distance from a certain highway, forest park or place of work.

Improve integration within the organization

Many organizations using GIS have found that one of its key benefits lies in new opportunities to improve the management of their own organization and its resources by geographically combining existing data and the possibility of their sharing and coordinated modification by different departments. The possibility of joint use and the database that is constantly growing and corrected by different structural divisions allows to increase the efficiency of the work of both each division and the organization as a whole. So, a company engaged in engineering communications can clearly plan repair or maintenance work, starting with obtaining complete information and displaying on a computer screen (or on paper copies) the relevant areas, for example, a water supply system, and ending with the automatic identification of residents who will be affected by these works. and notifying them of the timing of the proposed shutdown or interruptions in water supply.

Make Better Decisions

GIS, like other information technologies, confirms the well-known adage that better information helps you make better decisions. However, GIS is not a tool for issuing decisions, but a tool that helps to speed up and increase the efficiency of the decision-making procedure, providing answers to queries and functions for analyzing spatial data, presenting analysis results in a visual and easy-to-understand form. GIS helps, for example, in solving such tasks as providing various information at the request of planning authorities, resolving territorial conflicts, choosing the optimal (from different points of view and according to different criteria) places for placing objects, etc. The information required for decision-making can be presented in a concise cartographic form with additional textual explanations, graphs and diagrams. Availability of information accessible for perception and generalization allows decision-makers to focus their efforts on finding a solution without spending significant time on collecting and thinking through the available heterogeneous data. You can quickly consider several solutions and choose the most effective and effective.

Creating maps

GIS maps have a special place. The GIS mapping process is much simpler and more flexible than traditional manual or automatic mapping methods. It starts by creating a database. As a source of obtaining the initial data, you can also use the digitization of conventional paper maps. GIS-based cartographic databases can be continuous (without division into separate sheets and regions) and not associated with a specific scale. On the basis of such databases, it is possible to create maps (in electronic form or as hard copies) for any territory, of any scale, with the necessary load, with its selection and display with the required symbols. At any time, the database can be replenished with new data (for example, from other databases), and the existing data can be adjusted as necessary. In large organizations, the created topographic database can be used as a basis for other departments and divisions, while data can be quickly copied and sent over local and global networks.

GIS in Russia

The most common foreign systems in Russia are: software product ArcGIS company ESRI, product family GeoMedia corporations Intergraph and MapInfo Professional company Pitney Bowes MapInfo.

From domestic developments, the GIS Map 2008 program of the company has become widespread CJSC KB "Panorama".

Other software products of domestic and foreign development are also used: GIS INTEGRO, MGE corporations Intergraph (uses MicroStation as its graphics core), IndorGIS, STAR-APIC, DublGIS, Mappl, GeoGraph GIS, 4geo etc.

The introduction of information systems in various spheres of human activity find their place in the field of geodesy and related, related and other terrestrial fields of research. Following a parallel course with the emergence and development of satellite geodesy, information systems provided technological, managerial, geological, meteorological, cartographic, transport, diversified opportunities for obtaining the necessary spatial information of a certain degree of accuracy.

Any geographic information system (GIS) is, in modern terms, primarily a project based on scientific and practical data with the aim of obtaining some kind of end result on a given topic.

GIS is a kind of new form of geo-prospecting, related to the collection and processing of the necessary data by methods of geodesy, applied mathematics and created computer applications.

The phrase "geographic information system" contains three fundamental words that reveal its essence.

All objects of exploration and research inside, near and on the earth's surface are associated with the word "geo".

Methods of processing and transforming the received information into the necessary digital graphic product are associated with the "information" component of the phrase.

The "system" is considered to be a connecting component that gives integrity to the entire picture of research and unites all its elements and parameters into a spatial form.

Geographic information systems can be considered as software tools that allow you to work with spatially related information, with a geo-image, but not with a simple image, but which is registered. The registration (binding) process implies certain actions to orient images in a specific way in a particular coordinate system. It is this capability that is considered the main feature of GIS, unlike other programs.

It also has special tools that allow you to make an ordinary map a real model of an existing surface. So at a certain moment the idea came to combine the map with information, that is, the map is not in itself, but it has special attributes (descriptive characteristics) that are nonspatial. Correlation of spatial information with nonspatial information, linking into a single system and creation of analysis tools led to the emergence of GIS structures. The combination of positional and non-positional information can be considered the main know-how of GIS constructions.

Geographic information system structure

Geographic information structure consists of four components:

• The first part involves the collection of data and materials from all kinds of primary sources of information; there are positional (gridded) and non-positional (descriptive, in attribute tables) primary sources;
• The second part consists of a selection of the necessary data and its storage on computer media;
• The third part is technological, which serves to systematize, describe, compare, highlight, and most importantly analyze data in various ways;
• The fourth part is the resultant, with the conclusions of the final results in the required forms in accordance with the terms of reference.

GIS Opportunities

In the process of working with geographic information systems, it can be concluded that they allow you to give quick answers to many questions and make optimal decisions in various areas of human activity, namely:

• what is in certain areas of the location?
• Where is the specific object located?
• Evaluate the dynamics of changes in time, space, volumes, and so on;
• what spatial structures exist?
• Allows modeling with specific design specifications (for example, a cartogram of earth masses)

The main functionalities of GIS applications are as follows:

• Registration of geo-images;
• Creation of new geo-images (vectorization);
• Creation of databases and their statistical processing;
• Analysis and processing of spatial data (geoanalysis);
• Analysis of nonspatial (attributive) data;
• Visualization and mapping;
• Data storage.

Types of geographic information construction

It is necessary to highlight the possibilities to classify GIS according to different criteria:

• Territorial (global, national, regional, territorial, local)
• On a thematic basis (geological, agricultural, forest, meteorological, urban and others)
• By functional characteristics (multiscale, space-time)

Prospects for the development of geoinformation structures

Currently, the following are considered promising directions for the development of the geoinformation order:

• earth remote sensing data (everything that we get from space multispectral images of various ranges, radio data from artificial earth satellites);
• global positioning (GPS technology) with GIS applications in the communication space;
• internet and geographic information systems (storage of information on the network using the "cloud" technology, search engines, other portals);
• GIS television;
• GIS2 (Self-learning GIS).

LECTURE 1. GENERAL INFORMATION ABOUT GEOGRAPHIC INFORMATION SYSTEMS

1.1 Concept of geographic information systems

Geographic information system or geographic information system (GIS) is an information system that provides collection, storage, processing, analysis and display of spatial data and related nonspatial data, as well as obtaining information and knowledge about geographic space on their basis.

It is believed that geographic or spatial data constitutes more than half of all circulating information used by organizations engaged in various activities in which it is necessary to take into account the spatial distribution of objects. GIS is focused on ensuring the possibility of making optimal management decisions based on the analysis of spatial data.

The key words in the definition of GIS are spatial data analysis or spatial analysis. GIS can answer the following questions:

What's in the given area?

Where is the region that satisfies a given set of conditions?

Modern GIS has expanded the use of maps by storing graphic data in the form of separate thematic layers, and the qualitative and quantitative characteristics of their constituent objects in the form of databases. Such data organization, with flexible mechanisms for managing them, provides fundamentally new analytical capabilities.

1.2 "Data", "information", "knowledge" in geographic information systems

Concretizing the terms "data", "information", "knowledge" in relation to their operation in an information system, it can be noted that, having much in common, these concepts differ in their essence.

Data is understood as a set of facts known about objects, or the results of measurements of these objects. The data used in GIS is highly formalized. Data is like a building block in the process of creating information, as it is obtained in the process of data processing.

With regard to GIS, information is understood as a set of information that determines the measure of our knowledge about an object.

In this context, knowledge can be viewed as the result of the interpretation of information. The most general definition: knowledge is the result of cognition of reality, which has been confirmed in practice. Scientific knowledge is distinguished by its systematic nature, validity and a high degree of structuring.

Information systems can be viewed as an effective tool for gaining knowledge.

The differences between the terms “data”, “information” and “knowledge” can be traced in the history of the development of technical systems, so at first there were data banks, later information systems, then systems based on knowledge - intelligent systems (expert systems).

Currently, the software market offers several types of systems that work with spatially distributed information, in particular, computer-aided design, automated mapping and GIS systems. GIS in comparison with other automated systems have advanced tools for spatial data analysis.

.3 Generalized functions of GIS systems

Most modern GIS implement complex information processing using the following functions:

Data entry and editing;

Support for spatial data models;

Data storage;

Coordinate system transformation and map projection transformation;

Raster-vector operations;

Measuring operations;

Polygonal operations;

Spatial analysis operations;

Various types of spatial modeling;

Digital terrain modeling and surface analysis;

Conclusion of results in different forms.

.4 GIS classification

GIS systems are developed to solve scientific and applied problems for monitoring environmental situations, rational use of natural resources, as well as for infrastructural design, urban and regional planning, for taking operational measures in emergency situations, etc.

Many tasks that arise in life have led to the creation of various GIS that can be classified according to the following criteria:

By functionality:

Full-featured general purpose GIS;

specialized GIS are focused on solving a specific problem in any subject area;

information and reference systems for home and information and reference use.

The functionality of GIS is also determined by the architectural principle of their construction:

closed systems - do not have expansion options, they are capable of performing only the set of functions that are uniquely defined at the time of purchase.

open systems are distinguished by ease of adaptation, expansion capabilities, since they can be completed by the user himself using a special device (built-in programming languages).

By spatial (territorial) coverage:

Global (planetary);

nationwide;

regional;

local (including municipal).

By problem-thematic orientation:

General geographic;

ecological and nature management;

sectoral (water resources, forestry, geological, tourism, etc.);

By way of organizing geographic data:

Vector;

raster;

vector-raster GIS.

1.5 Data sources and their types

As data sourcesfor the formation of GIS are:

- cartographic materials (topographic and general geographic maps, maps of administrative-territorial division, cadastral plans, etc.). The information obtained from the maps is geographically referenced, so it is convenient to use them as a base GIS layer. If there are no digital maps for the study area, then the graphic originals of the maps are converted into digital form.

remote sensing data (RS) are increasingly used to form GIS databases. ERS, first of all, includes materials obtained from space carriers. For remote sensing, a variety of technologies are used for obtaining images and transmitting them to the Earth, carriers of imaging equipment (spacecraft and satellites) are placed in different orbits, equipped with different equipment. Due to this, images are obtained that differ in a different level of visibility and detail of displaying objects of the natural environment in different ranges of the spectrum (visible and near infrared, thermal infrared and radio ranges). All of this leads to a wide range of environmental problems solved with the use of remote sensing data.

Remote sensing methods include aerial and ground surveys and other non-contact methods such as hydroacoustic surveys of the seabed relief. The materials of such surveys provide both quantitative and qualitative information about various objects of the natural environment.

field survey materials territories, include data from topographic, engineering and geodetic surveys, cadastral surveys, geodetic measurements of natural objects performed by levels, theodolites, electronic total stations, GPS receivers, as well as the results of a survey of territories using geobotanical and other methods, for example, studies on the movement of animals, analysis soils, etc.

statistical data contain data from state statistical services for a variety of sectors of the national economy, as well as data from stationary measuring stations of observations (hydrological and meteorological data, information on environmental pollution, etc.)).

literature data (reference editions, books, monographs and articles containing a variety of information on certain types of geographic objects).

In GIS, only one type of data is rarely used, most often it is a combination of various data on any territory.

LECTURE 2. BASIC GIS COMPONENTS

The main components of GIS include: technical, software, information support. Requirements for GIS components are determined, first of all, by the user who faces a specific task (accounting for natural resources, or managing the city's infrastructure), which must be solved for a certain area, which differs in natural conditions and the degree of its development.

.1 Hardware

Technical support is a set of hardware used in the operation of a GIS: a workstation or personal computer (PC), information input-output devices, data processing and storage devices, telecommunication facilities.

A workstation or PC is the core of any information system and is designed to control the work of a GIS and perform data processing processes based on computational or logical operations. Modern GIS is able to quickly process huge amounts of information and visualize the results.

Data entry is carried out using various technical means and methods: directly from the keyboard, using a digitizer or scanner, through external computer systems. Spatial data can be obtained by electronic geodetic instruments, directly using a digitizer and a scanner, or from the results of processing images on analytical photogrammetric devices or digital photogrammetric stations.

Devices for processing and storing data are concentrated in a system unit, which includes a central processor, random access memory, external storage devices and a user interface.

Data output devices must provide a visual presentation of the results, primarily on a monitor, as well as in the form of graphic originals obtained on a printer or plotter (plotter); in addition, it is mandatory to export data to external systems.

.2 Software

Software - a set of software tools that implement the functionality of a GIS, and program documents required for their operation.

Structurally, GIS software includes basic and applied software tools.

Any GIS works with data of two types of data - spatial and attributive. For their maintenance, the software must include a database management system for those and other data (DBMS), as well as modules for controlling data input and output tools, a data visualization system and modules for performing spatial analysis.

Application software tools are designed to solve specialized problems in a specific subject area and are implemented as separate applications and utilities.

2.3 Informationth security

Information support - a set of information arrays, information coding and classification systems. Information support consists of implemented solutions by types, volumes, placement and forms of information organization, including the search and assessment of data sources, a set of data entry methods, database design, their maintenance and meta-maintenance. The peculiarity of storing spatial data in GIS is their division into layers. The multilayer organization of an electronic map, with a flexible layer management mechanism, allows you to combine and display much more information than on a conventional map. Location data (geographic data) and associated tabular data can be prepared by the user or purchased. A spatial data infrastructure is essential for this data exchange.

The spatial data infrastructure is determined by regulatory documents, mechanisms for organizing and integrating spatial data, as well as their availability to different users. A spatial data infrastructure includes three essential components: basic spatial information, spatial data standardization, metadata databases, and a data exchange mechanism.

LECTURE 3. STRUCTURES AND DATA MODELS

3.1 Display of real world objects in GIS

Real world objects considered in geoinformatics differ in spatial, temporal and thematic characteristics.

Spatial characteristics determine the position of an object in a predetermined coordinate system, the main requirement for such data is accuracy.

Temporal characteristics record the time of the study of an object and are important for assessing changes in the properties of an object over time. The main requirement for such data is relevance, which means that it can be used for processing, irrelevant data is outdated data.

Thematic characteristics describe various properties of an object, including economic, statistical, technical and other properties, the main requirement is completeness.

To represent spatial objects in GIS, spatial and attribute data types are used.

Spatial data - information that characterizes the location of objects in space relative to each other and their geometry.

Features are represented using the following graphics: points, lines, regions, and surfaces.

The description of objects is carried out by specifying the coordinates of objects and their constituent parts.

Point objects are such objects, each of which is located only at one point in space, represented by a pair of coordinates X, Y. Depending on the scale of mapping, such objects can be considered a tree, house or city.

Linear objects are presented as one-dimensional, having one dimension - length, the width of the object is not expressed in a given scale or is not significant. Examples of such objects: rivers, boundaries of municipal districts, contours of the relief.

Areas (polygons) - areal objects, represented by a set of pairs of coordinates (X, Y) or a set of line-type objects that represent a closed contour. Such objects can represent territories occupied by a certain landscape, city, or an entire continent.

Surface - when describing it, you need to add elevation values \u200b\u200bto areal objects. Surface restoration is carried out using mathematical algorithms (interpolation and approximation) according to the original set of coordinates X, Y, Z.

Additional nonspatial data about objects forms a set of attributes.

Attribute data is the qualitative or quantitative characteristics of features, usually expressed in alphanumeric form.

Examples of such data: geographical name, species composition of vegetation, soil characteristics, etc.

The nature of spatial and attributive data is different; accordingly, the methods of manipulation (storage, input, editing, search and analysis) for these two components of the geographic information system are also different. One of the main ideas embodied in traditional GIS is the preservation of the relationship between spatial and attribute data, with their separate storage and, partially, separate processing.

The general digital description of a spatial object includes: name; location indication; set of properties; relationships with other objects. The name of an object is its geographical name (if any), its conditional code or identifier assigned by the user or the system.

Objects of the same type in terms of spatial and thematic features are combined into layers of a digital map, which are considered as separate information units, while it is possible to combine all available information

.2 Data structures

Vector and raster data structures are used to represent spatial data in GIS.

A vector structure is a representation of spatial objects in the form of a set of coordinate pairs (vectors) that describe the geometry of objects (Fig. 1).

Figure: 1. Vector representation of spatial data

The raster data structure assumes the presentation of data in the form of a two-dimensional grid, each cell of which contains only one value that characterizes the object corresponding to the raster cell on the ground or in the image. As such a characteristic can be an object code (forest, meadow, etc.), height or optical density.

The precision of raster data is limited by the cell size. Such structures are a convenient means of analyzing and visualizing various kinds of information.

Figure: 2. Raster data structure

Various data models have been developed to implement raster and vector structures.

.3 Data Models

Spatial data models - logical rules for the formalized digital description of spatial objects

Vector data models. There are several ways to combine vector data structures into a vector data model that allows you to explore relationships between objects in the same layer or between objects in different layers. The simplest vector data model is the "spaghetti" model (Fig. 3). In this case, the graphic image of the card is translated “one to one”.

Figure: 3. "Spaghetti" -model

This model does not contain a description of the relationships between objects, each geometric object is stored separately and is not associated with others, for example, the common boundary of objects 25 and 26 is recorded twice, although using the same set of coordinates. All relationships between objects must be calculated independently, which complicates data analysis and increases the amount of stored information.

Vector topological models (Fig. 4) contain information about the neighborhood, proximity of objects and others, characteristics of the relative position of vector objects.

Figure: 4. Vector topological data model

Topological information is described by a set of nodes and arcs. A node is the intersection of two or more arcs and its number is used to refer to any arc to which it belongs. Each arc starts and ends either at the intersection with another arc, or at a node that does not belong to other arcs. Arcs are formed by a sequence of line segments connected by intermediate points. In this case, each line has two sets of numbers: pairs of intermediate point coordinates and node numbers. In addition, each arc has its own identification number, which is used to indicate which nodes represent its beginning and end.

Other modifications of vector models have been developed, in particular, there are special vector models for representing surface models, which will be discussed below.

Raster models are used in two ways. In the first case - for storing the original images of the terrain. In the second case, for storing thematic layers, when users are not interested in individual spatial objects, but in a set of points in space that have different characteristics (elevations or depths, soil moisture, etc.), for operational analysis or visualization.

There are several ways to store and address the values \u200b\u200bof individual raster cells, and their attributes, layer names, and legends.

When using raster models, the issue of raster data compression is relevant, for which methods of group coding, block coding, chain coding and representation in the form of a quadtree have been developed.

.4 Data formats

Data formats determine the way of storing information on the hard disk, as well as the mechanism for its processing Data models and data formats are interconnected in a certain way.

There are a large number of data formats. It can be noted that many GIS support the main storage formats for raster data (TIFF, JPEG, GIF, BMP, WMF, PCX), as well as GeoSpot, GeoTIFF, which allow transferring information about the binding of a raster image to real geographic coordinates, and MrSID for compression information. The most common vector format is DXF.

All systems support the exchange of spatial information (export and import) with many GIS and CAD systems through the main exchange formats: SHP, E00, GEN (ESRI), VEC (IDRISI), MIF (MapInfo Corp.), DWG, DXF (Autodesk), WMF (Microsoft), DGN (Bentley). Only a few, mainly domestic systems, support Russian exchange formats - F1M (Roskartografiya), SXF (Military Topographic Service).

Quite often, for the efficient implementation of some computer operations, a vector format is preferred, and for others a raster format. Therefore, some systems implement the ability to manipulate data in either format, and functions for converting vector to raster, and vice versa, raster to vector formats.

.5 Databases and management

The collection of digital data about spatial objects forms a set of spatial data and constitutes the content of databases.

Database (DB) - a set of data organized according to certain rules that establish general principles for describing, storing and manipulating data

The creation of a database and access to it (on request) is carried out using a database management system (DBMS).

The logical structure of the database elements is determined by the selected database model. The most common database models are hierarchical, networking and relational and object-oriented.

Hierarchical models represent a tree structure, in which case each record is associated with only one record at a higher level.

Such a system is well illustrated by the classification system for plants and animals. An example is also the structure of information storage on PC disks. The main concept of such a model is level. The number of levels and their composition depends on the classification adopted when creating the database. Any of these records can be accessed by traversing a strictly defined chain of nodes. With such a structure, it is easy to search for the required data, but if the initial description is incomplete, or some search criterion is not provided, then it becomes impossible. For fairly simple tasks, such a system is effective, but it is practically unsuitable for use in complex systems with online query processing.

Network models were intended to address some of the shortcomings of hierarchical models. In the network model, each entry in each node on the network can be associated with several other nodes. The records that are part of the network structure contain pointers that determine the location of other records associated with them. Such a model allows you to speed up access to data, but changing the structure of the database requires significant effort and time.

Relational models collect data into unified tables. The table is assigned a unique name within the database. Each column is a field named after the attribute it contains. Each line in the table corresponds to an entry in the file. One and the same field can be present in several tables. Since the rows in the table are not ordered, one or more columns are defined whose values \u200b\u200buniquely identify each row. This column is called the primary key. The relationship between tables is supported by foreign keys. Data manipulation is carried out using operations that generate tables. The user can easily enter new data into the database, combine tables by selecting individual fields and records, and create new tables for display on the screen.

Object-oriented models are used if the geometry of a particular object is capable of spanning several layers, the attributes of such objects can be inherited, and specific methods are used to process them.

To process the data placed in tables, additional information about the data is required, they are called metadata.

Metadata - data about data: catalogs, reference books, registers and other forms of describing sets of digital data.

LECTURE 4. TECHNOLOGIES OF DATA ENTRY

4.1 Methods of data entry

According to the technical means used, two methods of data entry are distinguished: digitalization and vectorization. A digitizer is used for manual input of spatial data. It consists of a tablet (table) with an electronic grid, to which a device called a cursor is attached. The cursor is a kind of graphic manipulator - a mouse, has a sight, applied to a transparent plate, with which the operator performs precise aiming at individual map elements. There are buttons on the cursor that allow you to fix the beginning and end of a line or area border, the number of buttons depends on the level of complexity of the digitizer. Digitizers come in a variety of formats and provide 0.03 mm resolution with an overall accuracy of 0.08 mm at a distance of 1.5 m. Automated digitizers are available to provide automatic line tracking.

Scanners are the most widely used for data entry. They allow you to enter a bitmap of a map into a computer. There are various types of scanners, which differ: according to the method of supplying the source material (flatbed and broaching (drum type); according to the method of reading information (working in transmission or reflection); according to radiometric resolution or color depth; according to optical (or geometric) resolution. The latter characteristic is determined by the minimum size of the image element, which is distinguished by the scanner.

.2 Transformation of raw data

The scanned source maps were created in a specific map projection and coordinate system. When digitized, this complex projection is reduced to a set of spatial coordinates. Therefore, it is necessary to convert the map to its original projection. For this, information about the projection used is entered into the GIS (usually GIS allows you to work with a large number of projections) and a number of transformations are performed. The three main ones that are often performed at the same time are translation, rotation and scaling.

Moving is simply moving the entire artwork to a different location on the coordinate plane. It is performed by adding certain values \u200b\u200bto the X and Y coordinates of the object:

Scaling is also very useful, since maps of different scales are often scanned, for this they use the ratio:

Rotation is performed using trigonometric functions:

All necessary transformations can be performed using these three basic graphical operations on the coordinates of the control points.

.3 Entering Remote Sensing Data

GIS does not use the primary remote sensing data obtained during the survey, but the derivatives formed as a result of their processing. Satellite data is digitally pre-processed to eliminate radiometric and geometric distortions, atmospheric influences, etc. To improve the visual quality of the original images, procedures can be used to change the brightness and contrast, filtering to remove noise, or emphasize outlines and fine details. When using aerial photographs, you should pay attention to the distortions caused by the angles of inclination of images and the terrain, which can be eliminated in the process of transformation or orthophoto transformation.

LECTURE 5. SPATIAL DATA ANALYSIS

5.1 Tasks of spatial analysis

Spatial analysis tools include various procedures for manipulating spatial and attribute data that are performed when processing user requests. (For example, operations of overlaying graphical objects, tools for analyzing network structures or selecting objects based on specified characteristics).

Each GIS package has its own set of spatial analysis tools that provide a solution to specific user tasks, at the same time, a number of basic functions can be distinguished that are inherent in almost every GIS package. This is, first of all, the organization of the selection and combination of objects in accordance with the specified conditions, the implementation of computational geometry operations, the analysis of overlays, the construction of buffer zones, network analysis.

.2 Basic functions of spatial data analysis

Selecting objects by request: the simplest form of request is to obtain the characteristics of an object indicated by the cursor on the screen and the reverse operation, when objects with given attributes are displayed. More complex queries allow you to select objects based on several criteria, for example, based on the distance of some objects from others, coincident objects, but located in different layers, etc.

SQL queries are used to select data in accordance with certain conditions. To execute queries of varying complexity, the possibilities of using mathematical and statistical functions, as well as geographic operators, allowing you to select objects based on their relative position in space (for example, whether the analyzed object is inside another object or intersects with it), have been implemented.

Data generalization can be carried out according to the equality of the values \u200b\u200bof a certain attribute, in particular for the zoning of the territory. Another way of grouping is to combine objects of one thematic layer in accordance with their placement inside polygonal objects of other thematic layers.

Geometric functions: these include the calculations of the geometric characteristics of objects or their relative position in space, using the formulas of analytical geometry on the plane and in space. So for areal objects, the areas or perimeters of boundaries they occupy are calculated, for linear objects - the lengths, as well as the distances between objects, etc.

Overlays (topological layers) are one of the most common and effective tools. As a result of superposition of two thematic layers, another additional layer is formed in the form of a graphic composition of the original layers. Considering that the analyzed objects can be of different types (point, line, polygon), different forms of analysis are possible: point to point, point to polygon, etc. The most commonly analyzed polygon alignment.

Build buffer zones. One of the tools for analyzing the proximity of objects is the construction of buffer zones. Buffer zones are areas (polygons), the boundary of which is at a specified distance from the boundary of the original feature. The boundaries of such zones are calculated based on the analysis of the corresponding attribute characteristics. In this case, the width of the buffer zone can be both constant and variable. For example, the buffer zone around the source of electromagnetic radiation will have the shape of a circle, and the zone of pollution from the chimney of the plant, taking into account the wind rose, will have a shape close to an ellipse.

Network analysis allows the user to analyze spatial networks of connected linear features (roads, power lines, etc.). Usually, network analysis is used to determine the nearest, most profitable path, determine the level of network load, determine the address of an object or route at a given address, and other tasks.

.3 Analysis of spatial distribution of objects

Analysis of the spatial distribution of objects. In fact, in many cases, it is necessary to know not only the amount of space occupied by objects, but also the location of objects in space, which can be characterized by the number of objects in a certain area, for example, the distribution of population. The most common methods for analyzing the distribution of point objects. The point distribution is measured by density. It is determined as the result of dividing the number of points by the value of the area of \u200b\u200bthe territory on which they are located. In addition to the distribution density, the shape of the distribution can be estimated. Point distributions occur in one of four possible variants: uniform (if the number of points in each small subdomain is the same as in any other subdomain), regular (if the points separated by equal intervals throughout the entire area are located at grid nodes), random, cluster (if the points are collected in close groups).

Point distributions can be described not only by the number of points within subdomains. Local relationships within pairs of points are often analyzed. The calculation of this statistic involves determining the average distance to the nearest neighboring point among all possible pairs of nearest points. This method allows us to estimate the measure of the sparseness of points in the distribution.

The distribution of lines is also estimated by density. Typically, calculations are performed to compare different geographic areas, such as the density of a hydrographic network. Lines can also be judged for proximity and possible intersections. Orientation, focus and connectedness are other important characteristics.

The analysis of the distribution of polygons is similar to the analysis of the distribution of points, however, when assessing the density, it is not the number of polygons per unit area that is determined, but the relative fraction of the area occupied by the polygon.

geographic information software graphic

LECTURE 6. MODELING OF SURFACES

6.1 Surface and digital model

Digital elevation models are the basis for presenting data on the earth's surface.

Surfaces - these are objects that are most often represented by Z height values \u200b\u200bdistributed over the area defined by the X and Y coordinates.

Digital elevation models (DEM) are used to represent the earth's surfaces in a computer.

DEM - a means of digital representation of the earth's surface relief

The construction of a DEM requires a certain form of presentation of the initial data (a set of coordinates of points X, Y, Z) and a method of their structural description, which allows the surface to be restored by interpolation or approximation of the initial data.

.2 Data sources for DEM generation

Initial data for the formation of DEM can be obtained from maps - digitizing contours, from stereopairs of images, as well as as a result of geodetic measurements or laser scanning of the area. The first method is most common, since Collecting images from stereopairs is laborious and requires specific software, but at the same time, it allows you to provide the desired degree of detail in the representation of the earth's surface. Laser scanning is a promising modern method, which is still quite expensive.

6.3 Interpolations

Building a DEM requires a specific data structure, and the source points can be differently distributed in space. Data collection can be carried out on the points of a regular grid, along the structural lines of the relief or randomly. Primary data using various operations lead to one of the most common GIS structures for representing surfaces: GRID, TIN, or TGRID. (Triangulated Irregular Network) - an irregular triangulation network, a system of non-overlapping triangles. The vertices of the triangles are the original anchor points. In this case, the relief is represented by a polyhedral surface, each face of which is described either by a linear function (polyhedral model), or by a polynomial surface, the coefficients of which are determined by the values \u200b\u200bat the vertices of the faces of the triangles. To obtain a surface model, you need to connect pairs of points with edges in a certain way, called Delaunay triangulation (Fig. 5).

Figure: 5.TIN model

The Delaunay triangulation applied to two-dimensional space is formulated as follows: a system of interconnected non-overlapping triangles has the smallest perimeter if none of the vertices falls inside any of the circles described around the formed triangles (Fig. 6).

The resulting triangles are as close as possible to equilateral. Each of the sides of the formed triangles from the opposite vertex is visible at the maximum angle of all possible points of the corresponding half-plane. Interpolation is performed along the formed edges.

Figure: 6. Delaunay triangulation

A distinctive feature and advantage of the triangulation model is that there are no transformations of the original data in it. On the one hand, this does not allow the use of such models for detailed analysis, but on the other hand, the researcher always knows that there are no introduced errors in this model, which the models obtained using other interpolation methods sin. This is the fastest interpolation method. However, if in the early versions of most GIS the triangulation method was the main one, today models in the form of a regular matrix of elevation values \u200b\u200bare widely used - the model is a regular matrix of elevation values \u200b\u200bobtained by interpolating the initial data. For each cell in the matrix, the height is calculated based on interpolation. In fact, this is a mesh, the dimensions of which are set in accordance with the accuracy requirements of a particular problem being solved. The regular grid matches the earth's surface, not the image.

Figure: 7. Density of points in the GRID model

(triangulated grid) - a model that combines elements of the TIN and GRID models. Such models have their advantages, for example, they allow using additional data to describe complex relief forms (cliffs, rocky ledges).

Surface reconstruction is implemented based on the interpolation of the original data.

Interpolation - restoration of a function on a given interval from its known values \u200b\u200bof a finite set of points belonging to this interval.

Currently, dozens of surface interpolation methods are known, the most common: linear interpolation; inverse distance weighted method, kriging; spline interpolation; trend interpolation.

Kriging is an interpolation method based on the use of mathematical statistics. Its implementation uses the idea of \u200b\u200ba regionalized variable, i.e. a variable that varies from place to place with some apparent continuity, so it cannot be modeled with just one mathematical equation. The surface is considered as three independent quantities. The first is a trend that characterizes the change in the surface in a certain direction. Further, it is assumed that there are small deviations from the general trend, such as small peaks and troughs, which are random, but still spatially related to each other.

Random noise (such as boulders). Each of the three variables must be operated on separately. The trend is estimated using a mathematical equation that most closely represents the total surface change, much like a trend surface.

Figure: 8. Elements of kriging: 1 - trend, 2 - random but spatially related altitude fluctuations, 3 - random noise

The expected change in height is measured using a variogram, on which the distance between samples is plotted along the horizontal axis, and half-dispersion on the vertical axis. Half-dispersion is defined as half of the variance between the heights of the original points and the heights of adjacent points. The best fit curve is then drawn through the data points. The dispersion at some point reaches a maximum and remains constant (the limiting correlation radius is revealed).

Inverse Distance Weighted Method: This method is based on the assumption that the closer the origin points are to each other, the closer their values \u200b\u200bare. For an accurate description of the topography, the set of points, which will be used for interpolation, must be selected in a certain vicinity of the determined point, since they have the greatest influence on its height. This is achieved in the following way. Enter the maximum search radius or the number of points that are closest in distance from the starting (defined) point. Then the value of the height at each selected point is given a weight, calculated depending on the square of the distance to the point to be determined. This ensures that closer points contribute more to the determination of the interpolated height than more distant points.

Trend interpolation . In some cases, the researcher is interested in general surface trends that are characterized by the trend surface.

Similar to the inverse distance weighted method, a trend surface uses a set of points within a specified neighborhood. Within each neighborhood, a best-fit surface is constructed based on mathematical equations such as polynomials or splines.

Trend surfaces can be flat, showing a general trend, or more complex. The type of equation used or the degree of the polynomial determines the amount of waviness in the surface. For example, a first-order trend surface will look like a plane that intersects the entire surface at an angle. If a surface has one bend, then such a surface is called a second-order trend surface.

Spline interpolation. The ability to describe complex surfaces using polynomials of low degrees is determined by the fact that with spline interpolation, the entire territory is divided into small non-intersecting sections. The polynomial approximation is carried out separately for each section. Usually a third degree polynomial is used - a cubic spline. Then a general “gluing” function is constructed for the entire region, with the specification of the continuity condition at the boundaries of the sections and the continuity of the first and second partial derivatives, ie. smoothness of gluing polynomials is ensured.

Smoothing with spline functions is especially useful when modeling surfaces that are complicated by discontinuities, and avoids distortion such as "edge effects".

LECTURE 7. TECHNOLOGY OF CONSTRUCTION OF DIGITAL RELIEF MODELS

7.1 Basic processes

The main processes of building DEM using maps are:

) Converting source maps to bitmaps, i.e. scanning. When scanning, it is important to choose the resolution of the resulting image, an unnecessarily high resolution requires large amounts of memory to store the initial information, at the same time the resolution should provide the necessary accuracy of information collection, which is determined by the goals of DEM formation.

) Installation of raster fragments. Editing or "stitching" is the joining of several free-form images into one so that the borders between the original images are invisible. During editing, raster data are georeferenced. The GIS has various modules for this task.

) Vectorization of a bitmap. Vectorization or digitalization of contour lines can be performed in manual, semi-automatic and automatic modes. For various GIS, separate modules have been developed that implement this task in automatic modes, for example, Mar Edit.

) Formation of DEM. DEM is created based on interpolation methods and can be presented in different formats.

) Visualization of results. DEM provides visualization of surface information in different forms

.2 Requirements for process accuracy

In general, we can say that the more initial points, the more accurate the interpolation will be and the more likely the constructed surface model will adequately represent the earth's surface. However, there is a limit to the number of points (discreteness), since for any surface an excessive number of points usually does not significantly improve the quality of the result, but only increases the amount of data and computation time. In some cases, redundant data in specific areas can result in uneven surface representation and therefore uneven accuracy. In other words, more points does not always improve accuracy.

.3 Using DEM

Digital elevation models (DEM) are important for solving a number of applied environmental problems. To predict emergencies, for example, floods, assessing the degree of landscape change, etc. According to the results of the DEM analysis by means of GIS, maps of the slope angles (slopes) of the terrain and slope exposures are obtained, designated viewpoints, etc. To display the DEM, different forms are used.

LECTURE 8. METHODS AND MEANS OF VISUALIZATION

8.1 Electronic maps and atlases

Visualization (graphic reproduction, display) - the generation of images, including cartographic ones, and other graphics on display devices (mainly on a monitor) based on the transformation of the original digital data using special algorithms.

Maps remain the most compact and familiar way of presenting geographic information.

Electronic map (EC) is a cartographic image visualized on a monitor based on digital maps or GIS databases.

Electronic atlas (EA) is a visualization system in the form of electronic maps, an electronic cartographic work, functionally similar to an electronic map. Supported by software such as cartographic browsers that provide frame-by-frame viewing of raster images of maps, cartographic visualizers, desktop mapping systems. In addition to cartographic images and legends, electronic atlases usually include extensive textual comments, tabular data, and multimedia electronic atlases - animation, video sequences and sound.

Tables and graphs, which include various characteristics of objects (attributes) or their ratios, can be used as independent ones or in addition to other visualization tools.

Animations are used to show dynamic processes, i.e. sequential display of drawn static images (frames), as a result of which the illusion of a continuous change of images is created.

8.2 Map Ways to Display Data Analysis Results

To display the results of data analysis in GIS, a number of methods are implemented that are used to create thematic maps.

Dimensional symbols (icons) method - the analyzed characteristics of objects are displayed with special symbols, the size of which conveys quantitative information, and the shape and color of qualitative information.

Qualitative or (quantitative background) method - in this case, data with similar values \u200b\u200bare grouped and the created groups are assigned certain colors, types of symbols or lines.

Dot method - a visual means is a set of dots of the same size, each of which has a certain value of a quantitative indicator.

Column and circular localized charts - allow you to display the ratio of several characteristics, while the charts are geo-referenced (for example, at the point of the observation post they show the ratio of pollutants).

The isoline method is one of the widespread methods of displaying various indicators. With their help, maps of isohypsum (topographic and hypsometric), maps of isotherms, isobars, isocorrelates, etc. are formed. and etc.)

At the same time, two groups of isolines are distinguished: true isolines (characterize a continuous change in any indicator, these include horizontal lines) and pseudo-isolines displaying data of a statistical nature (for example, discrete values \u200b\u200bfrom emission sources). To represent isolines, different visual means are used: lines of different types, thicknesses and colors, layer-by-layer color coloring of the background (or shading) of the gaps between isolines.

.3 3D rendering

Three-dimensional surface (3D surface) - a digital volumetric representation of surfaces in the form of wire diagrams, using various types of projection, and the image can be rotated and tilted using a simple graphical interface.

Raster images can be generated to display the relief from DEM data.

Raster surface (image) - is formed according to the Grid-model, with each pixel being assigned a value proportional to the height of the corresponding grid cell.

Shadow relief (analytical shading of relief) is a raster display of a DEM, during the formation of which, in addition to the height of each section of the grid model, the illumination of slopes is taken into account.

The possibilities of combining 3D surfaces with other thematic layers have been implemented. To achieve realistic display of terrain objects, 3D surfaces are combined with cartographic or orthoimages.

Virtual terrain model (VMM) is a terrain model containing information about the terrain relief, its spectral brightness and objects located in a given territory, intended for interactive visualization. VMM allows you to provide the effect of being on the ground, it can be displayed in the form of a three-dimensional static scene (3D view) or in the flight simulation mode over the terrain, when the observer is at a point with specified coordinates.

LECTURE 9. STEPS AND RULES OF GIS DESIGN

The use of GIS for solving various problems, in different organizational schemes and with different requirements, determines different approaches to the GIS design process.

There are five main stages of the GIS design process.

Analysis of the decision making system. The process begins by identifying all types of decisions that require information to be made. The needs of each level and functional area must be considered.

Analysis of information requirements. It determines what type of information is needed to make each decision.

Aggregating solutions, i.e. a grouping of tasks in which decisions require the same or significantly overlapping information.

Information processing design. At this stage, a real system for collecting, storing, transferring and modifying information is being developed. Consideration should be given to the ability of staff to use computer technology.

Design and control over the system. The most important stage is the creation and implementation of the system. The performance of the system is assessed from different positions, if necessary, an adjustment is made. Any system will have drawbacks and therefore needs to be made flexible and adaptable.

Geographic information technologies are designed to automate many time-consuming operations that previously required a lot of time, energy, psychological and other costs from a person. However, different stages of the technological chain lend themselves to more or less automation, which can largely depend on the correct formulation of the initial problems.

First of all, this is the formulation of requirements for the information products used and the output materials obtained as a result of processing. These include the requirements for printing maps, tables, lists, documents; to search for documents, etc. As a result, a document should be created with the conventional name "General list of input data".

The next step is to determine the priorities, the order of creation and the main parameters (territorial coverage, functional coverage and data volume) of the system being created. Further, the requirements for the data used are established, taking into account the maximum possibilities of their application.

LECTURE 10. GIS CONCEPT AND REQUIREMENTS

.1 Types of GIS

Geographic Information System (GIS) is a system for managing, analyzing and displaying geographic information. Geographic information is represented as a series of geographic datasets that model the geographic environment through simple generalized data structures. GIS includes toolkits for working with geographic data.

Geographic information system supports several types for working with geographic information:

Geodatabase View: A GIS is a spatial database containing datasets that represent geographic information in the context of a general GIS data model (vector features, rasters, topology, networks, etc.)

Geovisualization View: A GIS is a collection of smart maps and other views that show features and relationships between features on the earth's surface. Different kinds of maps can be built and they can be used as “windows to the database” to support querying, analyzing and editing information.

Geoprocessing View: GIS is a set of tools for deriving new geographic datasets from existing datasets. Spatial data processing (geoprocessing) functions extract information from existing datasets, apply analytical functions to them, and write the results into new derived datasets.

In ESRI® ArcGIS® software, these three GIS views are represented by a catalog (GIS as a collection of geodatasets), a map (GIS as a smart cartographic view), and a toolbox (GIS as a toolbox for processing spatial data). All of them are integral parts of a full-fledged GIS and are used to a greater or lesser extent in all GIS applications.

Figure: 1. Three types of GIS

.2 Geodatabase view

GIS is a special type of database about the surrounding world - a geographic database (geodatabase). At the heart of GIS is a structured database that describes the world in geographic terms.

Here's a quick overview of some of the key principles that are important to understanding geodatabases.

.2.1 Geographical representation

When users design a geodatabase in a GIS database, they define how different features are presented. For example, parcels are usually represented as polygons, streets as centerlines, wells as points, and so on. These features are grouped into feature classes in which each set has a single geographic representation.

Each GIS dataset provides a spatial representation of some aspect of the surrounding world, including:

Ordered sets of vector objects (sets of points, lines and polygons)

Raster datasets such as digital elevation models or images

Spatial networks

Terrain topography and other surfaces

Geodetic survey datasets

Other types of data such as addresses, place names, map information

LECTURE 11. GIS INFORMATION MANAGEMENT

.1 General

GIS information management uses many of the concepts and characteristics of a standard information technology architecture that work well in a centralized corporate computing environment. For example, GIS datasets can be managed in relational databases like other corporate information. To operate on data stored in a database management system (DBMS), modern logic of application interaction is used. Like other transaction-based enterprise information systems, GIS is widely used to continually change and update geographic databases. However, GIS technology has a number of important features.

.2 GIS data complex

GIS data is usually large in volume and includes a large number of large elements. For example, a simple database query to fill in a typical business form would return several rows of data, while creating a map would require hundreds or even thousands of records from the database. In addition, the amount of vector or raster graphics information displayed can be many megabytes. In addition, GIS data has complex relationships and structures, such as transportation networks, territory topography, and topology.

11.3 Compiling GIS data is a non-trivial specialized process

Building and maintaining graphical datasets in GIS requires advanced editing tools. And to maintain the integrity and behavior of geographic vector features and rasters, they need specialized processing based on specific geographic rules and commands. Therefore, compiling data into GIS is costly. This is one of the reasons why users are encouraged to collaborate with GIS datasets.

.4 GIS - Transactional System

As with other database management systems, the GIS database is constantly updated with a variety of data. Therefore, a GIS database, like other databases, must support such transactions. That being said, GIS users have some special requirements for transactions. One of the main conditions is the ability to support long transactions.

In many cases, significant updates to the database are carried out in stages. For example, when applied to utilities, this work usually includes stages such as “development”, “proposal”, “acceptance”, “reconstruction” and “delivery”. This process is largely cyclical.

The terms of reference are first drawn up and submitted to the engineer, then gradually modified as the individual stages are implemented, and, finally, all the changes made are returned back to the corporate database.

The workflow for updating and transferring data can take days or months. However, the GIS database must still remain accessible to support day-to-day operations and ongoing updates, and users must be able to access their version of the common GIS database. Here are some more examples of data management workflows in GIS:

Offline Editing: Some users need the ability to “check out” portions of a GIS database and replicate (move) them to another location in an independent, separate system. For example, to edit some data in the field, you need to take some data with you, edit and update it in the field, and then send the changes to the main database.

Distributed Geographic Databases:

The regional database can be a partial copy of the corresponding "chunk" of the main corporate GIS database. These databases must be periodically synchronized to exchange changes made to each of them.

.5 Indirect (non-rigid) replication

Replication with loose coupling within the DBMS. Often, users want to keep the context of their GIS data in sync across multiple copies of a database (called replicas), where each location has its own local database updates. From time to time, users want to migrate these updates from each replica of the database to others and synchronize their content. In this case, the DBMS can be different (for example, SQL Server ™, Oracle® and IBM® DB2®).

12. GIS - DISTRIBUTED INFORMATION SYSTEM

.1 General

Most geographic information systems now have layer and table data coming from different organizations. Each organization develops more or less significant part, not all of the content of its GIS. Typically at least some of the data layers come from external sources. The need for data is an incentive for users to obtain new data in the most efficient and quickest ways, including purchasing parts of the databases for their GIS from other GIS users. Thus, the management of GIS data is carried out by several users.

.2 Interoperability

The distributed nature of GIS implies ample opportunities for interoperability between many GIS organizations and systems. Collaboration and collaboration between users is very important to GIS.

GIS users have long relied on mutually beneficial data exchange and sharing activities in their work. A real reflection of this fundamental need is the ongoing effort to create GIS standards. Adherence to industry standards and general GIS principles is critical to the successful development and widespread adoption of this technology. GIS must support the most important standards and be adaptable as new standards emerge.

12.3 GIS networks

Many geographic datasets can be compiled and managed as a common information resource and shared by the user community. In addition, GIS users have their own vision of how popular datasets can be exchanged over the Web.

Key Web sites, called GIS catalog portals, enable users to both upload their own information and search for geographic information available for use. As a result, GIS systems are increasingly connected to the World Wide Web and gain new opportunities for the exchange and use of information.

This vision has taken root in the minds of people over the past decade and is reflected in concepts such as the National Spatial Data Infrastructure (NSDI) and the Global Spatial Data Infrastructure (GSDI). These concepts are constantly evolving and gradually being introduced, not only at the national and global levels, but also at the district and municipal levels. In general terms, these concepts are included in the Spatial Data Infrastructure (SDI).

The GIS network is essentially one of the methods for introducing and promoting SDI principles. It brings together many user sites and facilitates the publication, search, and sharing of geographic information across the World Wide Web.

Geographic knowledge is initially distributed and poorly integrated. All the information you need is rarely contained in a separate database instance with its own data schema. GIS users interact with each other to retrieve the missing pieces of their GIS data. GIS networks make it easier for users to connect and share their geographic knowledge.

The GIS network includes three main building blocks:

Metadata catalog portals where users can search and find GIS information according to their needs

GIS nodes where users compile and publish sets of GIS information

GIS users who search, identify, access and use published data and services

12.4 Catalogs of GIS portals

An important component of the GIS network is the catalog of the GIS portal with a systematized register of various storage locations for data and information sets. Some GIS users act as data stewards, they compile and publish their datasets for sharing in different organizations. They register their information sets in the portal directory. By searching this directory, other users can find and refer to the information sets they need.

A GIS Catalog Portal is a Web site where GIS users can search and find the GIS information they need. The capabilities provided depend on the mix of GIS data, map, and metadata network services offered. Periodically, a GIS catalog portal site may conduct a survey of the catalogs of associated participating sites in order to publish and update one central GIS catalog. Thus, a GIS catalog can contain links to data sources available both on this site and on other sites. It is assumed that a series of such catalog nodes will be created, and on their basis a common network will be formed - the Spatial Data Infrastructure.

GIS data and services are documented in the form of catalog records in the GIS portal catalog, which can be used to search for candidates for use in various GIS applications.

One example of a GIS catalog portal is the US government's Geospatial One-Stop portal, see www.geodata.gov. This portal will enable governments at all levels and the general public to access geographic information more easily, faster and more cost-effectively.

LECTURE 13. COMPOSITION OF A MODERN GIS PLATFORM

GIS requirements affect the development and implementation of GIS software. Like other information technologies, GIS must provide ease of deployment for applications built on top of it to support the workflow and business requirements of any organization. This is achieved by creating a basic software platform that supports different types of geographic datasets, advanced data management, editing, analysis and visualization tools.

In this context, GIS software is increasingly seen as the IT infrastructure around which large, modern multi-user systems are built. The GIS platform must provide all the capabilities needed to support this broad vision.

These include:

Geographic database for storing and managing all geographic features

Web-based network for distributed geographic information management and sharing

Desktop and server applications for:

1. - data compilation,

2. - information requests,

Spatial analysis and geodata processing,

4. - creation of cartographic products,

Raster imaging and research,

6. - GIS data management;

Modular software components (engines - engines) for embedding GIS logic in other applications and specialized user programs;

Geographic information services for multi-level and centralized GIS systems.

LECTURE 14. BRIEF OVERVIEW OF THE SOFTWARE USED IN UKRAINE

In Ukraine, both professional and specialized GIS are used. Software products are formed on the basis of a modular principle. Usually, the basic module and the extension modules (or applications) are distinguished. The basic module contains functions that implement basic GIS operations, including software support for I / O devices, data export and import, etc. It should be noted that software products of different companies have a lot in common, since manufacturers are forced to borrow from each other certain technological developments. There are currently about 20 well-known GIS packages on the market that can be classified as fully functional.

Characterizing the properties of fully functional GIS, one can note their common features. All systems run on Windows platform. Only a few of them have versions running under other operating systems (Horizon - MS DOS, Unix, Linux, MC BC, Free BSD, Solaris, INTROS; PARK - MS DOS; Arc GIS Arc Info-Solaris, Digital Unix, AIX, etc .; ArcView GIS - Unix).

All systems support the exchange of spatial information (export and import) with many GIS and CAD systems through the main exchange formats.

The possibilities for working with attribute information are even more homogeneous. Most systems provide work with all major DBMS through ODBC and BDE drivers. The first among the supported or used DBMS is Oracle.

In the overwhelming majority of cases, modern fully functional GIS allows you to expand your capabilities. The main way to expand capabilities is programming in high-level languages \u200b\u200b(MS Visual Basic, MS Visual C ++, Borland Delphy, Borland C ++ Builder) with DLL and OCX libraries (ActiveX). Naturally, there are exceptions. Systems like MapInfo Professional use Map Basic, and AricView GIS systems use Avenue.

The most common foreign systems for various reasons are ArcView GIS, MapInfo Professioal, MicroStation / J. A similar list of domestic systems is headed by GeoGraph, Panorama (Map 2000), PARK, GeoLink.

Let's briefly characterize the most common software products, noting features and areas of application.

ArcGIS ArcInfo(developed by ESRI, USA) . A fully functional GIS consisting of two independently installable software packages - ArcInfo Workstation and ArcInfo Desktop. The first consists of three basic modules: ArcMap - displaying, editing and analyzing data, ArcCatalog - accessing and managing data, ArcToolbox - an advanced spatial analysis tool, management projections and data conversion. Additional modules provide the solution to the following tasks:

Arc COGO - a set of tools and functions for working with geodetic data;

Arc GRID - has a powerful set of tools for analyzing and managing continuously distributed numerical and qualitative features, presented in the form of regular models, as well as modeling complex processes;

ARC TIN - designed for modeling topographic surfaces;

Arc NETWORK - for modeling and analysis of topologically connected objects in the form of spatial networks, assessment and management of resources distributed over networks, and processes in such networks. Provides the creation of geographic information systems, the creation and maintenance of land, forest, geological and other cadastres, the design of transport networks , assessment of natural resources.

ArcGIS ArcView(developed by ESRI, USA). Desktop GIS, which provides the user with a means of selecting and viewing various geodata, editing, analyzing and displaying them (business, science, education, management, sociology, demography, ecology, transport, urban economy).

All ArcGis products can use additional modules to solve specialized spatial analysis tasks:

ArcGIS Spatial Analyst is a software module for working with raster surfaces. Allows you to analyze surface characteristics, as well as interpolate spatially distributed data for visualization and analysis of processes;

ArcGis 3D Analyst - a program for creating, visualizing and analyzing three-dimensional objects and surfaces;

ArcGIS Geostatistical Analyst - a new module for surface interpolation based on statistical analysis of spatially distributed data;

ArcView supports relational DBMS, has advanced business graphics (view form, tabular form, diagram form, layout creation), provides for the creation of professionally designed cartographic information and the development of its own applications.

MapInfo Professional(developed by MapInfo Corp. USA), one of the most widespread desktop GIS in Russia. MapInfo is specially designed for processing and analyzing information that has an address or spatial reference.

MapInfo implements:

search for geographic objects;

geometric functions: calculations of areas, lengths, perimeters, volumes enclosed between surfaces;

building buffer zones around any object or group of objects;

advanced SQL query language, queries are expression-based, perform joins, display available fields, allow subqueries, multi-table joins, and geographic joins.

computer design and preparation for the publication of cartographic documents.

Geographer(developed by the Center for Information Research, Institute of Geography, Russian Academy of Sciences, Russia). Provides the ability to create electronic thematic atlases and map compositions based on layers of digital maps and associated tables of attribute data. The main features of GeoGraph are as follows:

creation of spatial objects in the form of cosmetic layers with attribution tables linked to them;

a subsystem for managing attributive data, including joining tables, editing, fetching, sorting, queries by pattern, etc.

electronic thematic mapping, etc.

Panorama (Russia)Construction and processing of digital and electronic maps, maintenance of cartographic and attributive databases.

Separately, it is necessary to highlight professional multifunctional instrumental GIS, which provide the possibility of direct processing of remote sensing data. These include ERDAS IMAGINE, ERMapper, etc.

ER Mapper(developed by ER Mapper) Processing large volumes of photogrammetric information, thematic mapping (geophysics, natural resources, forestry). Accuracy, map printing, 3D visualization, library of algorithms.

ERDAS IMAGINE(developed by Leica) is a software package specially designed for processing and analyzing remote sensing data, providing a complete set of tools for analyzing data from any source and presenting results in various forms - from printed maps to 3D models. ERDAS IMAGINE is built on a modular basis in the form of basic kits - IMAGINE Essential, IMAGINE Advantage and IMAGINE Professional.

ERDAS IMAGINE implements:

ample opportunities for visualization and data import (supports more than 100 formats);

geometric correction;

enhancing transformations and GIS analysis;

decryption of images;

tools for image processing and construction of algorithms for spatial computing;

Informatization has touched today all aspects of the life of society, and it is difficult, perhaps, to name any sphere of human activity - from schooling to high state policy, where its powerful impact is not felt.

Computer science "breathes down the back of the head" to all earth sciences, catching up and dragging them along, transforming, and sometimes completely enslaving them in the pursuit of endless computer perfection. Scientists can no longer imagine their work today without computers and digital databases. In the geosciences, information technology has given rise to geoinformatics and geographic information systems (GIS), moreover, the word "geographic" in this case means "spatiality" and "territoriality", and also the complexity of geographic approaches.

GIS is a hardware-software and at the same time a man-machine complex that provides collection, processing, display and dissemination of data. Geographic information systems differ from other information systems in that all their data is necessarily spatially coordinated, that is, tied to a territory, to a geographic space. GIS is used in solving all kinds of scientific and practical problems. GIS helps to analyze and simulate any geographic situation, make forecasts and manage processes in the environment. GIS is used to study all those natural, social and natural-social objects and phenomena that study earth sciences and related socio-economic sciences, as well as cartography, remote sensing. At the same time, GIS is a complex of hardware devices and software products (GIS shells), and the most important element of this complex is automatic cartographic systems.

The GIS structure is usually presented as a system of information layers. Conventionally, these layers can be viewed in the form of a "puff cake" or whatnot, each shelf of which contains a map or digital information on a specific topic.

In the course of the analysis, these layers are "removed from the shelves", considered separately or combined in different combinations, analyzed and compared with each other. For a given point or area, you can get data on all layers at once, but the main thing is that it becomes possible to get derived layers. One of the most important properties of GIS is precisely that, based on the available information, they are able to generate new derived information.

Resource GIS is one of the most common types of GIS in geosciences. They are designed for inventory, assessment, protection and rational use of resources, for predicting the results of their operation. Most often, for their formation, existing thematic maps are used, which are digitized and entered into databases in the form of separate information layers. In addition to cartographic materials, GIS includes long-term observation data, statistical information, etc. An example is "GIS -" created by the countries of the Black Sea basin. With its diverse marine life, abundant fish resources, warm sandy beaches and unique coastal landscapes that attract tourists, this pool has experienced catastrophic environmental degradation in recent decades. This drastically reduces fish resources, reduces the recreational potential, and leads to the degradation of valuable coastal wetlands. For the centralized adoption of urgent measures to save the Black Sea, a “Black Sea Rescue Program” was developed. An important part of this program was the creation of a resource-ecological "GIS - Black Sea". This GIS performs two functions - modeling and informing about the whole and individual components of its environment. Information is necessary for conducting scientific research in the water area and the adjacent part of the Black Sea basin and for making decisions on the protection and protection of this unique water area. GIS - Black Sea contains about 2000 maps. They are enclosed in seven thematic blocks: geography, biology, meteorology, physical oceanography, chemical oceanography, biology, fish resources.

Geoinformation mapping

The interaction of geoinformatics and cartography has become the basis for the formation of a new direction - geoinformation, that is, automated modeling and mapping of objects and phenomena based on GIS.

With the introduction of GIS, traditional cartography has undergone a radical restructuring. It can only be compared with the changes that accompanied the transition from handwritten maps to printed polygraphic prints. Cartographers of past eras, in their wildest imaginations, could not foresee that instead of engraving on a lithographic stone, it would be possible to draw a map by moving the cursor over the computer screen. And today, geographic information mapping has almost completely replaced the traditional methods of compiling and publishing maps.

Software-Guided Mapping brings new perspectives on many traditional problems. The choice of the mathematical basis and layout of maps has fundamentally changed, computer maps can be quickly transferred from one projection to another, freely scaled, change the "slicing" of sheets, introduce new visual means (for example, blinking or moving signs on the map), use mathematical filters for generalization and smoothing functions, etc. The laborious operations of calculating lengths and areas, transformation of maps or their alignment have become routine procedures. Electronic cartometry was born. The creation and use of maps has become a single process; in the course of computer processing, images are constantly transformed, moving from one form to another.

GIS technologies have given rise to another new direction - operational mapping, that is, the creation and use of maps in real or near real time. Now it is possible to quickly, or rather say, timely inform users and influence the course of the process. In other words, when mapping in real time, the incoming information is immediately processed and maps are drawn up for assessment, monitoring, management, control over processes and phenomena changing at the same pace.

Operational computer maps warn (signal) about unfavorable or dangerous processes, allow you to monitor their development, make recommendations and predict the development of situations, choose options for stabilizing or changing the course of the process. Such situations are created, for example, when they occur, when you have to quickly monitor their spread and quickly take measures to eliminate the fire. During the period of snow melting and during catastrophic downpours, it is necessary to monitor river floods and, in emergency situations, changes in the ecological state of the territory. During the liquidation of the Chernobyl accident, cartographers did not leave computers day and night, drawing up operational maps of the movement of clouds of radioactive contamination over the territories adjacent to the source of the disaster. They also monitor the development of political events and military actions in hot spots of the planet. Initial data for operational mapping are aerial and space images, direct observations and measurements, statistical materials, results of polls, censuses, referendums, etc. Cartographic animations provide enormous opportunities and sometimes unexpected effects. Animation software modules are able to move maps or three-dimensional diagrams across the screen, change the display speed, move individual signs, make them flash and vibrate, change the color and illumination of the map, "highlight" or "shade" certain areas of the image, etc. For example, on the map changes the color of the areas at risk: the “safe” bluish color gradually turns into pinkish, and then into bright red, crimson, which means: dangerous, avalanches are possible! Very unusual for cartography effects are created by panoramas, changes in perspective, parts of the image (you can divide the "dissipation" and delete objects), illusion of movement over the map (to "fly around" the territory), including at different speeds. In the foreseeable future, the prospects for the development of cartography in the earth sciences are associated, first of all, and almost entirely with geoinformation mapping, when there is no need to prepare printed editions of maps: upon request, it will always be possible to get an image of the object or phenomenon under study on a computer screen in real time. Some cartographers believe that the introduction of electronic technology "marks the end of three hundred years of cartographic drawing and publishing of printed cartographic products." In return for maps, the user will be able to request and immediately receive all the necessary data in a machine-readable or visualized form. And even the very concept of "atlas" is proposed to be revised.

Cadastral engineers, designers, geologists and other professionals are often faced with the need to use map data in their work. Modern developments make it possible to receive images of the terrain from a satellite in the smallest detail, and specially created software - to use this information for analytical purposes and display it in the desired format.

Let's talk about structures that allow us to generalize and study geographic material for the implementation of the most reasonable and optimal measures in each case.

Definition of GIS (GIS): how the abbreviation stands and what it is

Geographic information systems (GIS) are advanced computer technologies that are used to create maps and assess actual objects, as well as incidents occurring in the world. This combines visualization and spatial views with standard database processes: entering information and generating statistical results.

It is the designated characteristics that allow these programs to be widely used to solve many problems:

Analysis of physical phenomena and events on the planet.

Comprehension and designation of their main reasons.

Study of the issue of overpopulation.

Planning of promising solutions in urban planning.

Assessment of the results of current business activities.

Environmental problems - pollution of localities, reduction of the size of forests.

In addition to global goals, with the help of such support, it is possible to regulate particular situations, for example:

Finding the optimal path between points.

Choosing a convenient location for the company.

Finding the desired building at the address.

Municipal tasks.

Geographic analysis is not a new direction. But the technologies we are considering are the most consistent with the requirements of our time. This is the most effective, efficient and convenient process that automates the collection of the relevant material and its processing.

Today, geographic information systems are a lucrative business that employs millions of people in different countries. In Russia alone, more than 200 different companies are developing and implementing such technologies in all areas of business.

It has several constituent elements.

Equipment. These are various types of computer platforms, from personal machines to global centralized servers.

Software.All the necessary tools for obtaining, processing and visualizing material are present here. Individual components can be designated components for:

Introducing and manipulating information;

Database Management (DBMS);

Displaying spatial queries;

Access (interface).

What manipulations are possible in programs

The utilities run several processes:

Input.This converts the material into the required digital format. During digitization, paper maps are taken as a basis, which are processed on scanners. This is true for large objects; for small tasks, you can enter information through a digitizer.

Manipulation. Technologies have different ways of modifying materials and designating certain parts that are necessary to complete the immediate task. For example, they allow you to bring the scale from different elements to a single value for further general processing.

Control. With a significant amount of information and a large number of users, it is rational to use database management systems to collect and structure material. The most commonly used relational model is when information is stored in tables.

Query and analysis. The program allows you to get answers to many primitive and more detailed questions, ranging from the identity of the owner of the site and ending with the preferred types of soil under a mixed object. It is also possible to create templates for finding a specific type of request. The analysis uses tools such as proximity assessment and overlay research.

Visualization. This is the desired result of most spatial actions. Maps are equipped with accompanying documentation, volumetric images, tabular values \u200b\u200band graphs, multimedia and photographic reports.

GIS types

The classification of geographic information systems is based on the principle of territory coverage:

Global(national and subcontinental) - provide an opportunity to assess the situation on a global scale. Thanks to this, it is possible to predict and prevent natural and man-made disasters, estimate the size of the disaster, plan the elimination of consequences and the organization of humanitarian aid. They have been used all over the world since 1997.

Regional (local, sub-regional, local) - operate at the municipal level. Such technologies reflect many key areas: investment, property, navigation, public safety, and others. They help make decisions in the development of a certain area, which contributes to attracting capital to it and the growth of its economy.

GIS stores factual information about objects in the form of a collection of thematic layers, grouped according to the principle of geographic location. This approach ensures the solution of diverse tasks for reorganizing the area and holding events.

To find the location of the object, the coordinates of the point, its address, index, number of the land plot, etc. are used. This information is applied to maps after the geocoding procedure.

Technologies can work with raster and vector models.

AT vector form the material is encoded and stored as a set of coordinates. It is more suitable for stable elements with constant properties: rivers, pipelines, landfills.

Raster schema includes blocks of information about individual components. It is adapted to deal with variable characteristics such as soil types and facility availability.

Related innovations

GIS works closely with other applications. Let's consider the connection and the main differences with similar information technologies.

DBMS. They serve to accumulate, store and coordinate different materials, therefore they are often included in the software support for geographic systems. Unlike the latter, they do not have tools for assessing and spatial image of data.

Desktop mapping tools. Maps are used as information, but they have limited capabilities for their management and analysis.

Remote sensing and GPS. Here, information is collected using special sensors: on-board cameras of aircraft, global positioning sensors, and others. In this case, the material is collected in the form of pictures with the implementation of their processing and study. However, due to the lack of some tools, they cannot be considered geographic information systems.

CAD. These are programs for drawing up various drawings, floor plans and architectural designs. They use a set of elements with fixed parameters. Many of them have the ability to import values \u200b\u200bfrom GIS.

Among such utilities, it is worth noting the products of the ZWSOFT company:

Powerful and affordable GIS for importing, exporting and managing geospatial data. When selected for use with ZWCAD / AutoCAD, this application runs inside the CAD platform and allows users to exchange geospatial data between the platform drawing and GIS files, GIS servers or GIS data stores, load vector and raster maps and underlays, and manage attribute data and tables data.

- analogue of GeoniCS. Allows you to automate design and survey work. At the same time, drawings are created that comply with the current design regulations and standards. Contains six modules, the use of which solves various engineering, including geological, problems.

- analogue of GeoniCS Prospecting. Analyzes and interprets the results of laboratory and field research, performs statistical processing according to the specified parameters, calculates various normative and calculated indicators, generates reports according to the standards of the CIS countries.

- a utility for cadastral engineers with a full set of tools that automate the preparation of documents. Constant updating allows you to always provide up-to-date information on paperwork according to the requirements of the inspection authorities.

- computer-aided design system for architects, engineers, designers. Has a new core based on hybrid technologies, combining an intuitive interface, Unicode support, the ability to create three-dimensional models based on their sections. Has a built-in ability to insert raster maps using georeferencing files (geographic registration).

GIS examples for beginners

There are a lot of programs created for the purpose of such geographic analysis. Let's consider some of them as an example.

Mapinfo

The main functionality is:

the use of an understandable and convenient exchange scheme for transferring data to other structures;

the active window can be saved in different formats: bmp, tif, jpg and wmf;

support for a significant number of geographic projections and coordinate systems;

you can enter the material through a digitizer.

Using the utility, you can make thematic maps and build 3D landscapes.

DataGraf

A tool for spatial visualization, simulation of situations, construction of synthetic indicators. Optimal for learning the basics of computer mapping in educational institutions.

The program allows you to:

create vector maps;

bind an unlimited number of thematic databases to each element;

copy data to another file via the clipboard;

manually change the characteristics of objects and their location.

A simple tool for mastering the basic level. Solves mainly illustrative problems. Allows you to create digitized maps based on a regular picture and in any graphic format.

GIS application

The possibilities for using geographic technology are vast. Among the areas where these systems are most applicable are:

Land management. Needs utilities for compiling cadastres, calculating the areas of elements, marking the boundaries of land plots.

Object placement management. Here, their use is relevant for building an architectural plan, coordinating a network of industrial, retail and other special-purpose points.

Regional development. Engineering surveys of specific places, solving problems of optimizing infrastructure and attracting investors are currently impossible without a detailed study using such structures.

Protection of Nature. The programs allow carrying out environmental monitoring, planning the use of resources.

Emergency forecasting. Tracking changes in different geological states allows predicting the possibility of disasters, developing measures to prevent them and minimize losses from them.

Brief summary

We gave a decoding of the concept of GIS, examined in detail what geographic information systems are and where they are used. In conclusion, we will say that this is a very promising area that is actively developing. It is already impossible to imagine the work of specialists in many fields without the use of such technologies.