Computer lessons
→ ↓

The concept of gis. Free geoinformation solutions QGIS and NextGIS Geoinformation subsystem

Geographic Information System (GIS) is a means of visualizing spatial information and presenting it in a dynamic mode. GIS is a system for collecting, storing, analyzing and presenting cartographic information. In order for the GIS to be able to quickly respond to any new situation, a variety of thematic information is applied to the same spatial contour, including newly obtained information about the territory. Thanks to this capability, GIS allows you to model processes and phenomena and track changes in their state over time. GIS may include natural, biological, cultural, demographic or economic information.

GIS allows you to process arrays of component-by-component heterogeneous spatially coordinated information, maintain databases for a wide class of geographical objects, perceive and process spatial features of geo-ecological situations, implement an interactive user mode, quickly configure the system to solve various types of problems (assessment of the state of a resource, environmental mapping, making management decisions). A GIS has five main components: hardware, software, data, people, and methods. Hardware is the computer running the GIS. GIS operate on various types of computer platforms, from centralized servers to individual or networked personal computers.

The software contains the functions and tools needed to store, analyze and visualize geographic information. The key components of the software products are:

  • tools for entering and manipulating geographic information;
  • database management system;
  • tools to support spatial queries, analysis and visualization (display);
  • graphical user interface for easy access to tools.

Attitude data and associated tabular data can be collected and prepared by the user or purchased from suppliers. In the process of managing spatial data, a GIS integrates the latter with other types and sources of data, and can also use the database management system used by many organizations to organize and maintain the information at their disposal. GIS users may both technical specialists who develop and maintain the system, and ordinary users to whom GIS helps solve current affairs and problems.

A GIS stores information about the real world as a set of thematic layers that are aggregated based on geographic location. This simple but highly flexible approach has proven its value in solving a variety of real-world problems: tracking the movement of vehicles and materials, detailed display of real-life conditions and planned activities, and modeling global atmospheric circulation. All geographic information contains information about spatial location, whether it is a reference to geographic or other coordinates, or references to an address, postal code, electoral or census district, land or forest identifier, road name, etc. When such links are used, a procedure called geocoding is used to automatically determine the location of an object. This is a procedure for automated creation of map objects based on attribute data contained in a table. Depending on the nature of the data used, coordinate geocoding, geocoding by objects and address geocoding are distinguished. With its help, you can quickly find and see on the map where the object or phenomenon you are interested in is located.

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 and Y coordinates. The location of a point feature, such as a drill hole, is described by a pair of coordinates (X, Y). Linear features such as roads, rivers, or pipelines are stored as sets of X, Y coordinates. Polygon features such as river watersheds, parcels, or service areas are stored as a closed set of coordinates. The vector model is particularly useful for describing discrete objects and is less suitable for describing continuously changing properties such as soil types or object accessibility.

The raster model is optimal for working with continuous properties. A raster image is a set of values ​​for individual elementary components (cells). It is like a scanned map or picture. The entire study area is divided into elements of a regular grid or cell. Each cell contains only one value. It is spatially complete because any location in the study area corresponds to a raster cell, in other words, the raster model operates on elementary locations. In most raster data models, the smallest unit is a square or rectangle. Such units are known as grid, matrix or pixel. A set of cells forms a lattice, raster, matrix.

For use in GIS, data is converted into 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 scanning technology, which is especially important when carrying out large projects. If the amount of work is small, you can enter data using a digitizer. Many data have already been translated into formats that are directly understandable by GIS packages. With an increase in the volume of information and an increase in the number of users, it is advisable to use database management systems for storing, structuring and managing data. In GIS, it is most convenient to use a relational structure, in which data is stored in tabular form. GIS is widely used in the AIMS RSChS.

GIS among information technologies

The first question of a person unfamiliar with geographic information systems (GIS) will, of course, be: “Why do I need this?” Indeed, we rarely use atlases and maps in our lives. And in general, geography, as is known from the works of the classics, is also not necessary to study - there are cab drivers for that. In addition, we already receive more information, and not always pleasant information, from various sources than we would sometimes like. And does it still need to be systematized? There's a lot to think about here. But, if you look at it, GIS is more than a map transferred to a computer. So what is it and what is it eaten with?

But, unfortunately, with a brief, understandable to everyone and, as Professor Preobrazhensky from “Heart of a Dog” said, “factual” definition, everything is not so simple. The point, apparently, is that this technology, firstly, is largely universal, and secondly, it is developing so quickly and capturing new areas of life and activity that, as in an anecdote from the times of developed socialism, products (i.e. definitions) they don’t have time to deliver. The authors of each new fundamental book on GIS (and such books are constantly being published), and even more so of numerous monographs relating to one of the countless areas of their application, try to make their feasible contribution to the creation of such a definition. We refer you to these books if you want to find the most acceptable definition for you. Everyone who plunges into this world is free to give their own. We, without in any way claiming originality, will take what is already available.

Here, for example, are two definitions: one “lyrical”, the other “practical”. First: “This is an opportunity for a new look at the world around us.” Second: “GIS is a modern computer technology for mapping and analyzing objects in the real world, as well as events occurring on our planet, in our lives and activities.”

Without any definitions and just a description, this technology combines traditional database operations, such as querying and statistical analysis, with the benefits of rich visualization and geographic (spatial) analysis that a map provides. These capabilities distinguish GIS from other information systems and provide unique prospects for its use in a wide range of tasks related to the analysis and forecast of phenomena and events in the surrounding world, with the understanding and identification of the main factors and causes, as well as their possible consequences, with the planning of strategic decisions and the ongoing consequences of the actions taken.

One of the best ways to learn what GIS is is to see how other people use the technology. Well, then, without delay, start working with GIS and demonstrate your achievements to others. Any person with a creative attitude to business, when they see the possibilities of GIS, their hands immediately begin to itch... After all, GIS is also a toolkit with the help of which you can solve problems for which sometimes there are no ready-made complete solutions.

But let's go back to the beginning. At first glance, the only obvious thing is the use of GIS in the preparation and printing of maps and, perhaps, in the processing of aerial and satellite images. The real range of applications of GIS is much wider, and to appreciate it, we should look at the use of computers in general: then the place of GIS will be much clearer.

Computers not only provide great convenience for performing well-known operations with documents - they are the carriers of a new direction of human activity. This direction is information technology, and it is on them that modern society is largely based. What is it - information technology?

The term “information” is often understood too narrowly (like the “information” that journalists report). In reality, everything that can be represented in the form of letters, numbers and images should be called information. So, all the methods, techniques, techniques, means, systems, theories, directions, etc. etc., which are aimed at collecting, processing and using information, are collectively called information technologies. And GIS is one of them.

GIS is now a multi-million dollar industry involving millions of people around the world. Thus, according to Dataquest, in 1997, total sales of GIS software exceeded $1 billion, and taking into account related software and hardware, the GIS market is approaching $10 billion. GIS is studied in schools, colleges and universities. This technology is used in almost all spheres of human activity - be it in the analysis of such global problems as overpopulation, land pollution, hunger and overproduction of agricultural products, reduction of forest land, natural disasters, or solving specific problems such as finding the best route between points, selection of the optimal location for a new office, searching for a house at its address, laying a pipeline or power line in the area, various municipal tasks such as registering land property. How is it possible to solve such different problems using one technology? To understand this, let's look at the structure, operation and examples of GIS application in sequence.

Components of GIS

A working GIS has five key components: hardware, software, data, people, and methods.

Hardware. This is the computer running the GIS. Today, GIS operate on various types of computer platforms, from centralized servers to individual or networked desktop computers.

Software A GIS contains the functions and tools needed to store, analyze, and visualize geographic (spatial) information. The key components of software products are: tools for entering and manipulating geographic information; database management system (DBMS or DBMS); tools to support spatial queries, analysis and visualization (display); graphical user interface (GUI or GUI) for easy access to tools and functions.

Data. This is probably the most important component of GIS. Spatial location data (geographic data) and associated tabular data may be collected and produced by the user or purchased from vendors, commercially or otherwise. In managing spatial data, a GIS integrates spatial data with other data types and sources, and can also use the DBMSs used by many organizations to organize and maintain the data they have.

Performers. Widespread use of GIS technology is impossible without people who work with software products and develop plans for using them to solve real problems. GIS users can be both technical specialists who develop and maintain the system, and ordinary employees (end users) to whom GIS helps solve everyday affairs and problems.

Methods. The success and efficiency (including economic) of using GIS largely depends on a properly drawn up plan and work rules, which are established in accordance with the specific tasks and work of each organization.

How does GIS work?

A GIS stores information about the real world as a set of thematic layers that are aggregated based on geographic location. This simple but very flexible approach has proven its value in solving a variety of real-world problems: tracking the movement of vehicles and materials, detailed mapping of real-life conditions and planned activities, and modeling global atmospheric circulation.

All geographic information contains information about spatial location, whether it is a reference to geographic or other coordinates, or references to an address, postal code, electoral district or census district, land or forest identifier, road name or milepost on a highway, etc. When such links are used to automatically determine the location or locations of the feature(s), a procedure called geocoding is used. With its help, you can quickly determine and see on the map where the object or phenomenon you are interested in is located (the house where your friend lives or the organization you need is located; the place where an earthquake or flood occurred; a route along which it is easier and faster to get to the desired you point or 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 (in modern GIS, a third spatial coordinate and a fourth, for example, a temporal coordinate are often added). The location of a point (point object), for example a borehole, is described by a pair of coordinates (X,Y). Linear features such as roads, rivers, or pipelines are stored as sets of X,Y coordinates. 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 population density or accessibility of objects. The raster model is optimal for working with continuous properties. A raster image is a set of values ​​for individual elementary components (cells); it is like a scanned map or picture. Both models have their advantages and disadvantages. Modern GIS can work with both vector and raster data models.

Problems that GIS solves

General purpose GIS typically perform five procedures (tasks) with data, among others: input, manipulation, management, query and analysis, and visualization.

Enter. To be used in a GIS, data must be converted into 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. For a relatively small amount of work, data can be entered using a digitizer. Some GIS have built-in vectorizers that automate the process of digitizing raster images. Many data have already been translated into formats that are directly understandable by GIS packages.

Manipulation. Often, to complete a specific project, existing data must be further modified to meet the requirements of your system. For example, geographic information may be presented at different scales (street centerlines are at a scale of 1:100,000, census tract boundaries are at a scale of 1:50,000, and residential features 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 and the same map projection. GIS technology provides different ways to manipulate spatial data and extract the data needed for a specific task.

Control. In small projects, geographic information may be stored as regular files. But with an increase in the volume of information and an increase in the number of users, it is more effective to use database management systems (DBMS), special computer tools for working with integrated data sets (databases) for storing, structuring and managing data. 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 quite flexible and is widely used in many GIS and non-GIS applications.

Query and analysis. If you have GIS and geographic information, you will be able to get answers to both simple questions (who is the owner of this land plot? At what distance from each other are these objects located? Where is this industrial zone located?), and to more complex ones that require additional analysis (where is place to build a new house? what is the main type of soil under the spruce forests? how will the construction of a new road affect traffic?). Questions can be asked with a simple mouse click on a specific object, as well as through advanced analytical tools. Using GIS, you can identify and set search patterns and play out scenarios like “what will happen if...”. Modern GIS have many powerful tools for analysis. Among them, the two most significant are proximity analysis and overlap analysis. To analyze the proximity of objects relative to each other, GIS uses a process called buffering. It helps answer the following types of questions: How many houses are within 100 m 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 control building of this oil and gas production department? The overlay process involves the integration of data located in different thematic layers. In the simplest case, this is a mapping operation, but in a number of analytical operations, data from different layers is physically combined. Overlay, or spatial aggregation, allows, for example, the integration of data on soils, slope, vegetation and land tenure with land tax rates.

Visualization. For many types of spatial operations, the end result is a representation of the data in the form of a map or graph. A map is a very effective and informative way of storing, presenting and transmitting geographic (spatially referenced) information. Previously, maps were created to last for centuries. GIS provides amazing new tools that expand and advance the art and science of cartography. With its help, the visualization of the maps themselves can be easily supplemented with reporting documents, three-dimensional images, graphs, tables, diagrams, photographs and other means, such as multimedia.

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 single, generally accepted classification of information systems, the following description should help distance GIS from desktop mapping, CAD, remote sensing, database management systems (DBMS), and global technology. 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 - PC, Macintosh and low-end UNIX workstations.

CAD systems capable of creating project drawings, building and infrastructure plans. 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 have been extended to support cartographic representation of data, but, as a rule, the utilities available in them do not allow efficient management and analysis of large spatial databases.

Remote sensing and GPS. Remote sensing is both an art and a science for taking measurements of the earth's surface using sensors such as various cameras on board aircraft, global positioning system receivers and other devices. These sensors collect data in the form of sets of coordinates or images (nowadays predominantly digital) and provide specialized processing, analysis and visualization capabilities for the resulting data. Due to the lack of sufficiently powerful data management and analysis tools, the corresponding systems in their pure form, that is, without additional functions, can hardly be classified as real GIS.

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

What can GIS do for you?

Perhaps the main “trump card” of GIS is the most natural (for humans) presentation of both spatial information itself and any other information related to objects located in space (the so-called attribute information). The ways of presenting attribute information are different: it can be a numerical value from a sensor, a table from a database (both local and remote) about the characteristics of an object, its photograph or a real video image. Thus, GIS can help wherever spatial information and/or information about objects located in specific locations in space is used. From the point of view of their areas of application and economic effect, GIS can do the following:

  1. Make spatial queries and perform analysis. GIS's ability to search databases and perform spatial queries has enabled many companies to earn millions of dollars. GIS helps reduce the time it takes to respond to customer requests; identify areas suitable for required activities; identify relationships between various parameters (for example, soils, climate and crop yields); identify locations of power supply breaks. Realtors use GIS to find, for example, all the houses in a given area that have slate roofs, three bedrooms and 10-foot kitchens, and then provide more detailed descriptions of those structures. The request can be refined by introducing additional parameters, for example cost parameters. You can get a list of all houses located at a given distance from a certain highway, forested area or place of work.
  2. Improve integration within the organization. Many organizations using GIS have discovered that one of their main benefits lies in the new opportunities to improve the management of their organization and its resources based on the geographic integration of existing data, the ability to share and modify it in a coordinated manner across different departments. The possibility of collective use and a database that is constantly expanded and corrected by different structural divisions make it possible to increase the efficiency of both each division and the organization as a whole. Thus, a utility company can clearly plan repair or maintenance work, from obtaining complete information and displaying on a computer screen (or on paper copies) relevant areas, such as water pipes, to automatically identifying residents who will be affected by these works, and notifying them about the timing of the expected shutdown of heating or interruptions in water supply.
  3. Help make more informed decisions. GIS, like other information technologies, supports the well-known adage that better information leads to better decisions. But GIS is not a tool for making decisions, but a tool that helps speed up and increase the efficiency of the procedure for making decisions. It provides answers to queries and functions for analyzing spatial data, presenting analysis results in a visual and easy-to-read form. GIS help, for example, in solving such problems as providing a variety of information at the request of planning authorities, resolving territorial conflicts, choosing optimal (from different points of view and according to different criteria) locations for placing objects, etc. The information required for decision-making can be presented in a concise cartographic form with additional text explanations, graphs and diagrams. The availability of information that is accessible to perception and generalization allows decision-makers to focus their efforts on finding a solution without spending significant time collecting and understanding the available heterogeneous data. You can quickly consider several solution options and choose the most effective and cost-effective one.
  4. Create maps. Maps have a special place in GIS. The process of creating maps in GIS is simpler and more flexible than traditional manual or automatic mapping methods. It starts with creating a database. The digitization of ordinary paper maps can also be used as a source for obtaining initial data. GIS-based cartographic databases can be continuous (not divided into separate tiles or regions) and not associated with a specific scale or map projection. Based on such databases, it is possible to create maps (in electronic form or as hard copies) of any territory, of any scale, with the required load, with its selection and display with the required symbols. At any time, the database can be updated with new data (for example, from other databases), and the data available in it can be corrected and immediately displayed on the screen as needed. In large organizations, the created topographic database can be used as a basis by other departments and divisions; At the same time, it is possible to quickly copy data and send it over local and global networks.

"CAD and graphics" 5"2000

13.1. CONCEPTS ABOUT GEOINFORMATION SYSTEMS

At the end of the 20th century. Thanks to active automation and computerization, cartography has become the holder and manager of huge amounts of information about the most important aspects of the existence, interaction and functioning of nature and society. Informatization has penetrated into all areas of science and practice - from school education to high public policy.
In the geosciences, based on information technologies, geographic information systems (GIS) - special systems for collecting, storing, analyzing and graphically visualizing spatial data and related information about the necessary objects.
Spatial data (geographic data, geodata) - data about spatial objects and their sets. Spatial data forms the basis of information support for geographic information systems. The totality of spatial data recorded (saved) in one way or another is called spatial database.
One of the main functions of GIS is the creation and use of computer (electronic) maps, atlases and other cartographic works.
Geoinformation technologies are used with great success in the following industries:

  • mining - monitoring of mining enterprises, control over mining;
  • industrial production - enterprise design, calculations, audit and monitoring;
  • construction industry - communications design;
  • economics - conducting expert assessments, marketing planning, management;
  • administrative management - accounting of administrative subordination, information support of election campaigns, consulting, territory management;
  • ecology - solving problems in emergency situations, environmental monitoring;
  • Internet - Internet servers, location search and routing.

It is customary to distinguish the following territorial levels of GIS: global, national, regional, municipal and local.
GIS is also subdivided by problem orientation (topic). Specialized land information systems (LIS), cadastral (CIS), environmental (EGIS), educational, marine and many other systems have been created. One of the most common in geography is resource-type GIS. They are created on the basis of extensive and diverse information arrays and are intended for inventory, assessment, protection and rational use of resources, and forecasting the results of their operation.

13.2. GIS SUBSYSTEMS

Structure GIS is usually represented as a set information layers (Fig. 13.1). For example, the base layer contains terrain data, followed by layers of hydrography, road networks, settlements, soils, land cover, pollutant distribution, etc. Conventionally, these layers can be considered in the form of a “shelf”, on each shelf of which a map or digital information on a specific topic is stored.

Rice. 13.1. The principle of arranging information layers in a geographic information system

In the process of solving the assigned problems, the layers are analyzed individually or together in different combinations, their mutual overlay (overlay) and zoning are performed, correlations are calculated, etc. For example, using election data, you can build layers “voter turnout by election precinct” and “voting results for a particular party.” By analyzing these layers, we can draw conclusions about the work of agitators in the districts.


Rice. 13.2. Election results by precinct

When creating a GIS, the main attention is always paid to the choice of geographical basics And base map , which serves as a framework for subsequent linking, combining and coordinating all data entering the GIS, for mutual coordination of information layers and subsequent analysis using an overlay. Depending on the topic and problem orientation of GIS, the following can be chosen as basic:

  • maps of administrative-territorial divisions;
  • topographic and general geographical maps;
  • cadastral maps and plans;
  • photographic maps and photographic portraits of the area;
  • landscape maps;
  • maps of natural zoning and diagrams of natural contours;
  • land use maps.

Combinations of the above bases are also possible, for example, landscape maps with topographic maps or photo maps with land use maps, etc. In each specific case, the selection and additional preparation of a base map (for example, unloading it or applying additional information) constitute the central task of the stage of geographic and cartographic justification of the GIS.
core every GIS is automated mapping system (AKS) - a set of devices and software that ensures the creation and use of maps. The ACS consists of a number of subsystems, the most important of which are the subsystems input, processing And output information(Fig. 13.3).
The information input subsystem is a device for converting spatial information into digital form and entering it into computer memory or into a database. Digitizers and scanners are used for digitization. With the help of digitizers, contours and other symbols are traced and traced on the original map, and the current coordinates of these contours and lines in digital form are received in the computer memory. The operator performs the tracing process manually, which is associated with high labor intensity and the occurrence of errors when tracing lines. Scanners automatically read information sequentially across the entire field of the card, line by line. The card itself is placed on the tablet or on the reel. Scanning is performed quickly and accurately, but it is necessary to additionally separate (recognize) digitized elements: rivers, roads, other contours, etc. Qualitative and quantitative characteristics of digitized objects, as well as statistical data, are entered from a computer keyboard. All digital information goes into databases.


Rice. 13.3. GIS structure.

Database - ordered data sets on any topic (topics), presented in digital form, for example, databases on relief, settlements, geological or environmental information databases. The formation of databases, access to and work with them is provided by a database management system (DBMS), which allows you to quickly find the required information and carry out its further processing. If databases are located on several computers (for example, in different institutions or even in different cities and countries), then they are called distributed databases . This is convenient, since each organization forms its own array, monitors it and keeps it up to date. Sets of databases and their management tools form data banks . Distributed databases and data banks connect computer networks , and access to them (queries, search, reading, updating) is carried out under a single control.
Information processing subsystem consists of the computer itself, the control system and software. Hundreds of different specialized programs (software packages) have been created that allow you to select the desired projection, generalization techniques and image methods, build maps, combine them with each other, visualize and print. Software systems are capable of performing more complex work: analyzing the territory, deciphering images and classifying mapped objects, modeling processes, comparing, evaluating alternative options and choosing the optimal solution path. And modern “intelligent” programs even simulate some processes of human thinking.
Most of the information processing subsystems operate in a dialog (interactive) mode, during which there is a direct two-way exchange of information between the cartographer and the computer.
Output subsystem (distribution) of information - a set of devices for visualizing processed information in cartographic form. These are screens (displays), printing devices (printers) of various designs, drawing machines (plotters), etc. With their help, mapping results and solution options are quickly displayed in a form that is convenient for the user. This can be not only maps, but also texts, graphs, three-dimensional models, tables, but if we are talking about spatial information, then most often it is given in cartographic form, the most familiar and easily visible.
All subsystems included in automatic mapping systems are also included in GIS. The cartographic GIS for industrial purposes also includes map publishing subsystem , which allows you to produce printed forms and print circulation of cards. If the circulation is small, which is usually the case when carrying out scientific research, then desktop cartographic publishing systems are used.
GIS focused on working with aerospace information includes a specialized image processing subsystem. In this case, the software allows you to perform various operations with images: correct them, transform them, improve them, automatically recognize and decrypt them, classify them, etc.
A special subsystem in highly developed GIS can be a knowledge base, i.e. a set of formalized knowledge, logical rules and software tools for solving problems of a certain type (for example, for drawing boundaries or zoning a territory). Knowledge bases help diagnose the state of geosystems, offer solutions to problem situations, and make a development forecast. It can be considered that knowledge bases implement some principles of the functioning of artificial intelligence.

13.3. GEOINFORMATICS - SCIENCE, TECHNOLOGY, PRODUCTION

Geoinformatics exists in three forms as science, technology and production, and this is a fairly typical situation in the conditions of scientific and technological progress that brings science and production closer together. This trinity is one of the factors that brings cartography and geoinformatics closer together.
Geoinformatics as a scientific discipline studies natural and socio-economic geosystems through computer modeling based on databases and knowledge bases.
Together with cartography and other earth sciences, geoinformatics studies the processes and phenomena occurring in geosystems, but uses its own means and methods for this. The main ones are computer modelling And geographic information mapping .
The main goals of geoinformatics as a science are the management of geosystems in a broad sense, including their inventory, assessment, forecasting, optimization, etc. For cartography, the integrated approach to the phenomena under study and its problem orientation inherent in geoinformatics are especially important. The structure of geoinformatics includes such sections as the theory of geosystem modeling, methods of spatial analysis and applied geoinformatics.
But on the other hand, geoinformatics is a technology for collecting, storing, transforming, displaying and distributing spatially coordinated data. GIS technologies provide analysis of geoinformation and decision making.
Finally, geoinformatics as a production (geographic information industry) is the manufacture of equipment, the creation of commercial software products and GIS shells, databases, control systems, and computer systems. This area includes the formation of GIS infrastructure and the organization of marketing.
Cartography and geoinformatics interact in many ways. They are united organizationally, since state cartographic services and private firms are simultaneously engaged in geoinformation activities. A special direction of higher geoinformation and cartographic education has been formed.
The unity of the two branches of science and technology is determined by the following factors:
♦ general geographic and thematic maps - the main source of spatial information about nature, economy, social sphere, and environmental conditions;
♦ coordinate systems and layouts adopted in cartography serve as the basis for the geographic localization of all data in GIS;
♦ maps - the main means of interpreting and organizing remote sensing data and any other information received, processed and stored in GIS;
♦ geographic information technologies used to study the spatio-temporal structure, connections and dynamics of geosystems are mainly based on methods of cartographic analysis and mathematical cartographic modeling;
♦ cartographic images are the most appropriate form of presenting geoinformation to consumers, and mapping is one of the main functions of GIS.

13.4. GEOINFORMATION MAPPING

Geoinformation mapping is the automated creation and use of maps based on GIS and cartographic data and knowledge databases. The essence of geoinformation mapping is information and cartographic modeling of geosystems.
Geoinformation mapping can be sectoral and complex, analytical and synthetic. In accordance with accepted classifications, types and types of mapping are distinguished (for example, socio-economic, environmental or inventory, assessment geoinformation mapping, etc.).
This direction was not formed suddenly and not out of nowhere. It integrated a number of branches of cartography, raising them to a higher technological level. Its origins can be traced to complex, then to synthetic and evaluative-predictive mapping. The next step was the development of system mapping, in which attention is focused on the holistic display of geosystems and their elements (subgeosystems), hierarchy, relationships, dynamics, and functioning. This required solid reliance on mathematical methods and automated technologies, and from here it was already one step to the creation of automatic cartographic systems and GIS. In other words, geoinformation mapping arose and is developing as a direct continuation of complex, synthetic and then system mapping in a new geoinformation environment.
Among the characteristic features of this type of mapping, the most important are the following:
♦ high degree of automation, reliance on digital cartographic data bases and geographic (geological, environmental, etc.) knowledge bases;
♦ systematic approach to display and analysis of geosystems;
♦ interactivity of mapping, a close combination of methods for creating and using maps;
♦ efficiency approaching real time, including the widespread use of remote sensing data;
♦ multivariate, allowing for a versatile assessment of situations and a range of alternative solutions;
♦ multi-medium (multimedia), allowing you to combine iconic, text, and sound displays;
♦ use of computer design and new graphic visual aids;
♦ creation of images of new types and types (electronic maps, 3-dimensional computer models and animations, etc.);
♦ predominantly problem-based and practical orientation of mapping, aimed at supporting decision-making.
Geoinformation mapping is software-controlled mapping. It accumulates the achievements of remote sensing, space mapping, cartographic research method and mathematical cartographic modeling.
In its development, geographic information mapping uses the experience of complex geographical research and systemic thematic mapping. Thanks to this, at the end of the 20th century. geographic information mapping has become one of the main directions in the development of cartographic science and production.

13.5. OPERATIONAL MAPPING

Operational mapping - one of the branches of geoinformation mapping, its essence is the creation and use of maps in real or near real time in order to quickly (timely) inform users and influence the progress of the process.
The real time scale characterizes the speed of creation and use of maps, i.e. a pace that ensures immediate processing of incoming information, its cartographic visualization for assessment, monitoring and control of any processes and phenomena changing at the same pace.
In practical situations, the prompt production of cartographic works and their delivery to consumers become important and even decisive conditions for completing the task. Operational cards designed to solve a wide range of problems, and above all to warn (signal) about unfavorable or dangerous processes, monitor their development, make recommendations and forecasts, select control options, stabilize or change the course of a process in a variety of areas - from environmental situations to political ones events.
It is necessary to distinguish between two types of operational cards: some are designed for long-term subsequent use and analysis (for example, maps of voter results), and others on short-term application for immediate assessment of any situation (for example, maps of the stages of ripening of agricultural crops).
The initial data for operational mapping are materials from aerospace surveys, direct observations and measurements, statistical data, results of surveys, censuses, referendums, and cadastral information. And the effectiveness of operational mapping is determined by three factors:

  • reliability of the automatic system, speed of data entry and processing, ease of access to databases;
  • good readability of the operational maps themselves, simplicity of their external design, which ensures effective visual perception in the conditions of operational analysis of situations;
  • efficiency of card distribution and delivery to consumers, including the use of telecommunication networks.

Rapid display of the state and changes in phenomena is closely related to automated manufacturing dynamic maps . They make it possible to reflect not only the structure, but also the essence of phenomena and processes occurring in the earth’s crust, atmosphere, hydrosphere, biosphere and, more importantly, in the zones of their contact and interaction. Dynamic mapping is also the most effective means of visualizing monitoring results.

13.6. CARTOGRAPHIC ANIMATIONS

In traditional cartography, there are three ways to display the dynamics of phenomena and processes, their occurrence, development, changes in time and movement in space:

  • display of dynamics on one map using arrows or movement tapes, “growing” signs and diagrams, expanding areas, isolines of the rates of change of phenomena, etc.;
  • showing dynamics using a series of multi-time maps, photographs, photo maps, block diagrams, etc., recording the states of objects at different moments (periods) of time;
  • drawing up maps of changes in the states of a phenomenon, when not the dynamics themselves are shown, but only the results of the changes that have occurred (areas of change).

Geographic information mapping significantly expands the possibilities of displaying the dynamics of geosystems by introducing into practice cartographic animations (animations) - special dynamic sequences of map frames that create the effect of movement when demonstrated. Animations have firmly entered everyday life; they have become as familiar as space images and electronic maps. A well-known example is television weather forecast maps, which show the movements of fronts, areas of high and low pressure, and precipitation.
Many technologies and techniques for obtaining moving images have been developed. Special computer programs have been created that contain modules that provide a variety of options and combinations of cartographic animations:

  • moving the entire map across the screen;
  • cartoon sequences of frame cards or 3-dimensional images;
  • changing the demonstration speed, frame-by-frame viewing, returning to a favorite frame, reverse sequence;
  • moving individual content elements (objects, signs) across the map;
  • changing the type of content elements (objects, signs), their sizes, orientation, blinking signs, etc.;
  • color variation (pulsation and defiling), changing intensity, creating the effect of color vibration;
  • changing the illumination or background, “highlighting” and “shading” of individual areas of the map;
  • panning, changing projection and perspective (viewpoint, angle, tilt), rotating 3-dimensional images;
  • scaling (zooming) an image or part of it, using the “dissolve” effect or removing an object;
  • creating the effect of movement over the map (“flying” the territory), including at different speeds.

Animations can be shown at normal (24 frames per second), fast or slow speed. This gives rise to completely new problems for cartography: temporal generalization, choice of visual means, studying the principles of readers’ perception of moving maps, etc.
Dynamic images add a much-needed time dimension to traditional static maps. In this regard, it is justified to introduce the concept time scale (or time scale). In a certain sense, we can talk about slow-, medium- and fast-scale images. For example, one second of demonstration of an animated map corresponds (rounded) to one day, or one second corresponds to one month.

13.7. VIRTUAL MAPPING

Further development of geographic information technologies led to the creation of images that combine the properties of a map, perspective photograph, block diagram and computer animation. Such images are called virtual. This term has several semantic shades: possible, potential, non-existent, but capable of arising under certain conditions, temporary or short-lived, and most importantly - not real, but the same as real, indistinguishable from real. In computer graphics, virtual reality visualization primarily involves the use of three-dimensional effects and animation. They create the illusion of presence in real space and the possibility of interactive interaction with it.
In cartography, virtual models are understood as images of real or mental objects, formed and existing in a software-controlled environment. Like any cartographic image, they have a projection, scale and are generalized. Virtual reality itself is an interactive technology that allows you to reproduce real and (or) mental objects, their connections and relationships in a software-controlled environment.
It is believed that the rejection of conventional signs, the desire to give virtual images “naturalness”, volume, natural coloring and lighting creates the illusion of the real existence of an object. This speeds up the communication process and increases the efficiency of transferring spatial information.
Technologies for creating virtual images are diverse. Usually, first, a digital model is created from a topographic map, aerial or satellite image, and then a three-dimensional image of the area. It is painted in the colors of the hypsometric scale or combined with a photograph of the landscape and then used as a real model.
One of the most common virtual operations is “flying around” the resulting image. Special software modules provide flight control: movement in a chosen direction, turns, changing speed, showing perspective. Using a keyboard and a joystick (a manipulator in the form of a handle with buttons), you can maintain a flight at a given altitude, at a set speed, over points with pre-selected coordinates. In addition, it is possible to select the state of the sky (cloudiness), fog, lighting conditions of the area, the height of the Sun, time of day, effects of rain or snowfall, etc. Editing modules allow you to additionally add new thematic content, change the texture of the area, use colored grids and backgrounds, place inscriptions by choosing the size and color of fonts, add texts and even sounds.
Large-scale thematic virtual images provide a fairly detailed understanding of the relief and landscape, geological structure, water bodies, vegetation cover, cities, communication routes, etc. The ability to integrate different thematic information into a single model is one of the main advantages of a virtual image. Flying and “hovering” over the mountains, you can examine in detail the terraced nature of their slopes, carry out morphometric measurements, determine the nature of erosion and landslide processes, and moving over urban areas, you can assess the features of development and distribution of green areas, design the placement of new buildings and transport routes.
In virtual modeling, multilevel approximation is often used. Using the same digital model of relief, landscape or vegetation cover, several approximations are performed with different levels of detail. This allows you not to be limited to increasing or decreasing the scale, but, if necessary, to move to a different level of detail. This is how a kind of multi-level generalization arises.
Virtual images are most widely used in solving such practical problems as monitoring natural risk areas, construction of buildings and highways, laying pipelines, assessing environmental pollution and the spread of noise from airports, etc. It is possible to use similar technologies for scientific and educational purposes, for example, to create medium- and small-scale virtual images, including globes. The globes depict, say, the natural zonation of the globe, the course of climatic processes, seasonal changes in vegetation cover and landscape, population migration, traffic flows, etc. The subjects of virtual thematic maps are as varied as in traditional mapping.

13.8. ELECTRONIC ATLASES

The creation of capital atlases, as is known, takes a long time, and the main problem is their obsolescence, often while still in the process of preparation. Electronic atlases are a good alternative to paper ones. They allow you to significantly reduce the preparation time, use CDs as media, and use animations and multimedia tools. Such atlases contain high quality maps, have a user-friendly interface and are usually equipped with good reference and search systems.
There are several types of electronic atlases:

  • atlases for visual viewing only ("flipping"), so-called viewer atlases;
  • “interactive atlases”, which provide the ability to change the design, methods of depiction and even classification of mapped phenomena, enlarge and reduce (scale) the image, and obtain paper copies of maps;
  • “analytical atlases” that allow you to combine and compare maps, carry out their quantitative analysis and evaluation, perform overlays, spatial correlations - essentially, these are GIS atlases;
  • atlases located on computer telecommunications networks, for example Internet atlases. In addition to maps and interactive tools, their structure also necessarily contains tools for searching for additional information and maps on the Internet.
  • Maps of complex electronic atlases contain different types of information layers:
  • multifunctional base layers used for many maps;
  • analytical and synthetic layers on specific topics;
  • promptly updated thematic layers.

All of them can be included in the content of different atlas maps, for example, the base layer “geological structure” can be used not only for the geological map itself, but with one or another generalization - for maps of minerals, hydrogeological, engineering-geological, geoecological, etc. Combination layers significantly simplifies the labor-intensive processes of compiling and mutually agreeing maps.
Most countries have created national electronic atlases. As a rule, they are based on multi-volume paper atlases. However, electronic atlases do not always repeat their paper prototypes precisely due to the ongoing updating of maps, the emergence of new plots and even partial changes in structure.
For the first time in the history of the Ukrainian state, a National Atlas of Ukraine - a cartographic work of encyclopedic level. The Atlas reflects the entire range of knowledge about the modern territory of Ukraine. The electronic version combines traditional cartographic approaches and modern geoinformation technologies, which are designed to reflect comprehensive information about the history, natural, social and environmental features of Ukraine at the beginning of the 21st century.
The electronic version of the National Atlas of Ukraine is designed for a wide range of users. Everyone will find a lot of useful information for themselves: from schoolchildren and students to specialist geographers. The ability to work with the electronic version depends only on the skills and interest of the users.
The atlas contains 875 unique maps, which are created on the basis of the latest knowledge and statistical information, as well as texts, graphics and photographs. It organically combines six thematic blocks.
general characteristics . Information about the geopolitical position of Ukraine, its physical and geographical conditions and administrative structure, its place in the European and world natural resource, economic and demographic potential.
Story . Information about the main stages of the history of the Ukrainian people and state.
Natural conditions and natural resources . Information about the characteristics and quality of the country’s natural conditions, the availability and quantity of natural resources.
Population . Information on the size, distribution and movement of the population, settlement structure, national composition, features of demographic, socio-economic and humanitarian development.
Economy . Information reflecting the level of development of the productive forces of Ukraine, the structure, specialization and territorial organization of the economy and general trends in the transformation of the economy.
Ecological state of the environment . The maps reflect a comprehensive assessment of the state and level of pollution of the environment and individual components of nature, a monitoring system, a natural reserve fund and other protected areas.
The electronic version of the National Atlas of Ukraine is a unique collection on one disk of a great deal of information about Ukraine, and was prepared under the guidance of leading experts in their field. A user-friendly interface and ease of use ensure that you can easily find the information you need.

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

Computer science is “breathing down the neck” of all the Earth sciences, catching up and carrying them along, transforming, and sometimes completely enslaving them in the pursuit of endless computer perfection. Scientists today can no longer imagine their work without computers and digital information databases. In the geosciences, information technology gave rise to geoinformatics and geographic information systems (GIS), and the word “geographical” in this case means “spatiality” and “territoriality,” as well as the complexity of geographical approaches.

GIS is a hardware-software and at the same time human-machine complex that provides collection, processing, display and distribution of data. Geographic information systems differ from other information systems in that all their data is necessarily spatially coordinated, that is, tied to the territory, to geographic space. GIS is used to solve all kinds of scientific and practical problems. GIS help analyze and model any geographical situation, make forecasts and manage processes occurring in the environment. GIS is used to study all those natural, social and natural-social objects and phenomena that are studied by earth sciences and related socio-economic sciences, as well as cartography and 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 mapping systems.

The structure of a GIS is usually represented as a system of information layers. Conventionally, these layers can be considered in the form of a “layer cake” or whatnot, on each shelf of which a map or digital information on a specific topic is stored.

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

Resource GIS is one of the most common types of GIS in geosciences. They are intended for inventory, assessment, protection and rational use of resources, to predict 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 data from long-term observations, statistical information, etc. An example is “GIS -”, created by the countries of the Black Sea basin. This basin, with its diverse marine life, abundant fish resources, warm sandy beaches and uniquely beautiful coastal landscapes that attract tourists, has experienced catastrophic environmental degradation in recent decades. This sharply reduces fish resources, reduces recreational potential, and leads to degradation of valuable coastal wetlands. To centralize the adoption of urgent measures to save the Black Sea, they developed the “Program to Save the Black Sea”. An important part of this program was the creation of a resource and environmental “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 presented in seven thematic blocks: geography, biology, meteorology, physical oceanography, chemical oceanography, biology, and fisheries resources.

Geoinformation mapping

The interaction of geoinformatics and cartography became the basis for the formation of a new direction - geoinformation, i.e. automated modeling and mapping of objects and phenomena based on GIS.

With the introduction of GIS, traditional cartography has experienced a radical overhaul. It can only be compared with the changes that accompanied the transition from handwritten maps to printed printing. In their wildest dreams, cartographers of past eras could not have foreseen that instead of engraving on a lithographic stone, it would be possible to draw a map by moving a cursor across a computer screen. And these days, geographic information mapping has almost completely replaced traditional methods of compiling and publishing maps.

Software-driven mapping forces us to take a fresh look at 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 “cutting” of sheets, introduce new visual means (for example, flashing or moving signs on the map), use mathematical filters for generalization and smoothing functions, etc. Previously labor-intensive operations of calculating lengths and areas, transforming maps or combining them have become routine procedures. Electronic cartometry emerged. The creation and use of maps has become a single process; during computer processing, images are constantly transformed, moving from one form to another.

GIS technologies have given rise to another new direction - operational mapping, i.e. the creation and use of maps in real or near real time. There is an opportunity to quickly, or rather, promptly inform users and influence the progress of the process. In other words, with real-time mapping, incoming information is immediately processed and maps are drawn up for assessment, monitoring, management, and control of processes and phenomena that change at the same pace.

Operational computer maps warn (signal) about unfavorable or dangerous processes, allow you to monitor their development, give 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 arise, when it is necessary to quickly monitor their spread and quickly take measures to extinguish the fire. During the period of snow melting and during catastrophic downpours, it is necessary to monitor river floods and, and in emergency situations, changes in the ecological state of the territory. During the liquidation of the Chernobyl accident, cartographers did not leave their 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 operations in hot spots of the planet. The initial data for operational mapping are aerial and space images, direct observations and measurements, statistical materials, results of surveys, censuses, referendums, etc. Cartographic animations provide enormous opportunities and sometimes unexpected effects. Animation program modules are capable of moving maps or three-dimensional diagrams across the screen, changing the display speed, moving individual signs, making them blink and vibrate, changing the color and illumination of the map, “highlighting” or “shading” certain areas of the image, etc. For example, on on the map, the color of areas exposed to danger changes: the “safe” bluish color gradually turns into pinkish, and then into bright red, crimson, which means: dangerous, avalanches are possible! Effects that are completely unusual for cartography create panoramas, changes in perspective, parts of the image (you can divide “dissolves” and remove objects), illusions of movement over the map (perform a “fly around” of the territory), including at different speeds. In the foreseeable future, the prospects for the development of cartography in the geosciences are associated, first of all, and almost entirely with geoinformation mapping, when there is no need to prepare printed copies of maps: upon request, it will always be possible to obtain an image of the object or phenomenon being studied in real time on a computer screen. Some cartographers believe that the introduction of electronic technology "means the end of three hundred years of cartographic drawing and publishing of printed cartographic products." Instead of cards, the user will be able to request and immediately receive all the necessary data in machine-readable or visualized form. And even the very concept of “atlas” is proposed to be reconsidered.

Geographic Information Systems or simply geographic information systems (GIS) are spatial data management. Spatial data, in turn, is data that describes the location of objects in space, most often in the form of two or three-dimensional geometry. Geographic information systems allow you to do everything with spatial data that any other information systems do with their data, namely: they provide the ability to add, delete, update, query, view, analyze, etc.

There are two main formats for presenting spatial data: in the form of vector graphics and in the form of rasters:

Raster graphics or raster image is usually a two-dimensional array of dots, each of which is represented by a different color. Modern GIS allow you to work with raster images of almost any format from bmp, png and jpeg to TIFF/GeoTIFF. Raster graphics are usually used to design the “background” of a digital map, on top of which vector geometry is already displayed. You don’t have to look far for examples: open Google Maps or Yandex maps and there you will see a huge number of rasters. Very little is presented in the form of vector graphics on these maps, namely a road graph, territory boundaries and some other objects. The undeniable advantage of raster images on digital maps is that they allow you to display a huge amount of spatial information with relatively small amounts of memory. The downside is that the quality of the image on the raster decreases sharply with a significant increase in the display scale, therefore, for different scales, rasters of different territorial coverage and resolution are used, which replace each other as the image is enlarged and reduced. You can see how this happens when working with the same Google Maps and Yandex maps.

Vector graphics– this is, in fact, geometry presented in the form of sets of coordinates. The vector graphics presentation format does not store the image itself - it is generated “on the fly” by the GIS rendering (visualization) subsystem, and therefore the image quality is always high, regardless of the current scale. The following types of vector spatial data are distinguished:

  • Point geometry. It is used in cases where, on a given scale of an electronic map, only the location of an object is important. Typically, point geometry is represented as a point on a map of a specific color, but some GIS allow you to replace this point with a raster image or a vector symbol, such as an arrow, symbol, or icon. In addition to the coordinates of a point, the point geometry itself can be further parameterized by its orientation on a plane or in space, which determines the rotation angle of the corresponding symbol or icon on the map. Point geometry can be used to visualize almost any objects, with the exception of extended ones, since everything depends on the scale of the map.

  • Linear geometry. Used to represent objects for which it is important to reflect their extent (length) and linear configuration. Such objects include roads, rivers (on a small scale), sections of territorial borders and other similar objects. Again, on larger scales the same objects can already be depicted in the form of areal geometry.

  • Areal geometry. It is used when everything is important: location, length and area. For example, a plot with a house on a small scale can be represented by point geometry, and on a larger scale it can be represented by areal and linear geometry. Areal geometry is not only polygons, but also complexes consisting of linear fragments, arcs of various radii, and also containing holes represented by other polygons.

GIS and information modeling basics

Vector and raster geometry in GIS do not compete with each other, but each perform their own functions. Raster graphics are used to design a graphical representation of an electronic map. It helps the user navigate when viewing and searching for objects on the map, since the terrain is most often represented by aerial photographs of the area. Vector graphics are a means of representing objects on a map that are significant in the context of the current GIS configuration - those objects whose data is managed by the information system. If this is a city map, then streets, houses, engineering structures and other urban infrastructure objects are usually presented in the form of vector graphics. If these are utility networks, for example, water supply networks or heating networks, then significant objects in this case are additionally pipeline sections, central substations, equipment, etc.


The advantages of vector graphics, in addition to the above-mentioned constant image quality at any scale, include the ability to select objects on the map, edit their representation using built-in GIS tools, or perform spatial queries on such data.

Spatial query is a structured query to spatial data, the criteria of which are conditions associated with the coordinates of vector geometry. For example, you can query for all objects of a certain type that are inside a given outline, intersect a given boundary, or are within a certain distance from a given point.

Any non-graphic information that additionally characterizes a particular object in the system can also be associated with spatial data. Moreover, any object of an information model in a GIS can be represented by a set of spatial objects and sets of associated semantic attributes that describe this object in the same way as if it were represented in any non-graphical system. Let's say that if a GIS uses a DBMS to store its data, then the semantic part of the description of objects is records in tables of a relational database. Example: GIS manages gas pipeline network data. The “gas pipeline section” object in this case can be represented by linear geometry structures to view the network on a small map scale; areal geometry for a large scale and a separate table for storing its length, radius, material and other technical characteristics. Quite often, structured queries to data managed by GIS are a symbiosis of traditional database and spatial query parameters. For example, a request to select all sections of a gas pipeline of a certain radius in a territory specified by a certain polygon.

You can get acquainted with the basic principles of information modeling, which are also valid for GIS.

What does a geographic information system consist of and how does it work?

Subsystem for working with spatial data storages. There are GIS solutions that use databases as a spatial data storage, interacting with a DBMS. There are software products that store data in files of their own format, and there are those that can work with various sources of graphic information. The subsystem for working with spatial data repositories is the GIS software components responsible for creating connections with the repositories themselves and exchanging data with them, including via network protocols.

Coordinate systems control module. The coordinates by which spatial data is represented in a geographic information storage can correspond to either a rectangular (Cartesian) or a geographic coordinate system built on the basis of an ellipsoid. If earlier it was believed that the earth was round, then in our time its shape is described by a rather complex figure - geoid. The surface of the geoid coincides with the water level of the world ocean, which is conditionally extended under the continents. Ellipsoid, in turn, is the locus of points obtained by rotating the geoid around its main axis. I am not a specialist in geodesy, therefore I will not go into the intricacies of constructing earthly coordinate systems, but will continue my story from the perspective of a GIS user. The coordinate system can also be global (over the entire territory of the earth) or local - intended for positioning within certain limits of the earth's surface. There are local geographic coordinate systems, which for a specific area have higher accuracy than the world coordinate system. This is achieved due to the fact that such coordinate systems are built on the basis of a local ellipsoid that is more accurate in the conditions of a given area (in comparison with its global description). Rectangular coordinate systems, by their nature, are all local, since only in small areas the error associated with the fact that the earth is not flat, but round, does not interfere with the construction of relatively accurate maps. The origin of coordinates of such coordinate systems is chosen arbitrarily, and they are created for various purposes, including in order to have an idea of ​​​​the relative position of objects, but for security reasons exclude the possibility of obtaining their true (world) coordinates. An example of a local coordinate system is the local coordinate system of the city of Moscow, which has zero coordinates in the area of ​​the main building of Moscow State University.


The coordinate system control module is designed to convert points from the original coordinate system of the spatial data storage into plane coordinates, with which the graphics core of the operating system works, allowing the image to be displayed on the screen, printer and other output devices. This module is also responsible for the inverse transformation: transformation of the coordinates of a point on a plane into the coordinates of the information storage (world or local coordinates). The inverse transformation is used in the process of editing (digitizing) geometry using GIS tools. Most often, GIS deals with the WGS 84 (World Geodetic System) coordinate system, which is a single coordinate system for the entire territory of planet Earth. A geographic or, as it is also called, geocentric coordinate system, such as WGS 84, is an ellipsoidal coordinate system that determines the coordinates of objects relative to the center of mass of the earth. Geographic coordinate systems differ from each other by the shape of the ellipsoid on which they are based. The set of transformations that are used to transform the coordinates of a geographic coordinate system into a Cartesian coordinate system is called a map projection. In other words, map projection– is a reflection (unfolding) of an ellipsoid of a geographic coordinate system onto a plane. The most widely used projections are the UTM (Universal Transverse Mercator) projection and the Gauss-Kruger (GK) projection.

Legend or subsystem for setting up graphical representation. Any spatial data storage is represented by a set of vector and raster graphics objects. In 2D GIS, individual spatial data objects are often called layers, since the image formed in the electronic map window is created sequentially: the display subsystem “draws” each type of object in turn. Thus, the result of image formation is a multilayer two-dimensional picture, where each subsequent layer is applied on top of the previous one. A legend is the main tool in GIS, with the help of which it is determined not only the order in which objects are displayed on the map (the order of layers), but also the parameters of their display (color, line thickness, caption font, etc.). Using the legend, individual features can be included or excluded from the list of displayed layers on the map. The legend can describe the layers that represent the features retrieved by the spatial data subsystem from different connections. For example, one map combines topographic map (terrain) data from one source and utility network data (gas pipeline, heating network, etc.) from another source.

Display subsystem. An important parameter for setting up the graphical representation of spatial data is nominal map scale. It is when the scale of data display in the GIS electronic map window corresponds to the nominal scale, the thickness of the lines, font size and other parameters correspond to those specified in the legend, and in conditions of a different scale, which can be easily changed by the user, the thickness of the lines and font size will be increased or decreased accordingly. Thus, the nominal map scale is the reference point for the display subsystem. The principle by which the display subsystem forms a graphical representation of spatial data is largely determined by the legend of a particular map. A GIS workplace can consist of a whole set of electronic maps, each of which is represented by its own legend.

Spatial data editing subsystem. This is, in fact, a set of GIS user tools that allow you to edit spatial data. Drawing new or editing existing geometry usually comes down to sequentially indicating points on the map. When these points are selected, the coordinate system control module transforms the cursor coordinates on the screen into points corresponding to the information storage coordinate system. Modern graphical input systems can also allow, when specifying points, to “snap” to existing data, for example, to the corners or midpoints of polyline segments, to point geometry, etc.

Spatial data analysis subsystem. The same subsystem that allows you to configure, execute and display the results of spatial queries. The parameters for the graphical presentation of the results of spatial queries are also determined by means of the legend.

Printing subsystem. A type of display subsystem designed to output fragments of electronic maps to a printer or plotter (plotter). Additional functions of the printing subsystem, in comparison with the subsystem for displaying images on the screen, include setting up and generating a graphical representation on the printout of the legend itself, as well as a symbol for the scale, compass, and other attributes necessary for working with the paper version of the map.

Business logic subsystem. Any software used to configure the operation of a geographic information system to solve a specific application problem or group of problems. Such tools may include a subsystem for information modeling of a subject area, for integration with other information systems, and created, for example, on a built-in GIS and much more. The composition of the business logic subsystem for different software products of this class may differ significantly, or may be absent altogether, since everything depends on the purpose of a particular solution.

The most famous modern GIS

The most well-known representatives of GIS software components are the products of three American companies. These include Intergraph's Geomedia family of solutions, ESRI's ArcGIS products, and Pitney Bowes' MapInfo tools. In Russia, due to a number of circumstances, the last two are the most popular, although Geomedia in many aspects is a more universal and modern product. In particular, Geomedia and Geomedia Professional allow the user to work with spatial data of various formats directly (including ArcGIS and MapInfo data), without resorting to preliminary procedures for converting and importing them, while competing solutions prefer to work only with their data formats .

P.S. Examples of designing GIS subsystems in C# in the context of studying an object-oriented approach to programming, namely: classes for working with vector graphics, a subsystem for working with geoinformation storage, the architecture of a linear transformation service and some others are considered in a programming course.


More on the topic of the article: