Definition of geographic information system gis. Geographic information system

The use of GIS to solve different problems, in different organizational schemes and with different requirements, leads to different approaches to the GIS design process.

There are five main stages in the GIS design process.

1. Analysis of the decision-making system. The process begins by identifying all types of decisions that require information to make. The needs of each level and functional area must be taken into account.

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

3. Aggregation of decisions, i.e. grouping of tasks that require the same or significantly overlapping information to make decisions.

4. Design of the information processing process. On at this stage a real system for collecting, storing, transmitting and modifying information is being developed. The capabilities of personnel to use computer technology must be taken into account.

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

Geoinformation technologies are designed to automate many labor-intensive operations that previously required large amounts of time, energy, psychological and other costs from humans. However, different stages of the technological chain are amenable to greater or lesser automation, which may largely depend on the correct formulation of the initial tasks.

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

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

LECTURE 10. GIS CONCEPT AND REQUIREMENTS

Types of GIS

A 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 sets of tools for working with geographic data.

The Geographic Information System supports several views for working with geographic information:

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

2. Geovisualization View: GIS is a set of smart maps and other views that show spatial objects and relationships between objects on the earth's surface. Can be built different types maps, and they can be used as “windows into a database” to support queries, analysis and editing of information.

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

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

Rice. 1.

Geodatabase view

GIS is a special type of database about the world around us - a geographic database (geodatabase). At the heart of GIS is a structured database that describes the world from a geographic perspective.

Let's give brief overview Some key principles important to understanding geodatabases.

Geographical representation

When creating a GIS geodatabase design, users determine how different features will be represented. For example, parcels of land are typically represented as polygons, streets as centerlines, wells as points, etc. 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 world around us, including:

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

· Raster datasets such as digital models relief or image

· Spatial networks

Terrain topography and other surfaces

· Survey datasets

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

GIS (stands for Geographic Information Systems) - computer systems, making it possible to display data on the screen in electronic form. Images obtained through GIS belong to the new generation of maps.

Geography on the screen

In addition to geographic maps, such maps can be supplied with other data from the field of statistics, demography, etc. They allow different types of analytical operations that are not available for old paper media.

Technical support for electronic maps exists in the form of a huge number of analytics, editing tools, and extensive databases. When creating and using them, many modern tools are involved - from scanners to space satellites that take pictures of the earth's surface.

The information obtained with the help of new technologies is used not only by geographers, but also in business, construction, marketing, and public administration. Even housewives know what geographic information systems are. And they use electronic cards quite successfully!

GIS - definition and basic concepts

What exactly does this term mean? Geographic information systems(GIS) is the name of systems whose purpose is to collect, store and analyze spatial data, as well as their graphic visualization. GIS belongs to the new generation of computer technologies. The science that studies applied and technical aspects work with GIS, - geoinformatics.

GIS is a successful combination of the ability to work with databases (queries, analytics) and the spatial visualization characteristic of maps. Data is stored in such a system in thematic layers tied to geographic location. GIS work with both raster and vector data, so any problem related to spatial information can be effectively solved with their help.

What makes them different

TO characteristic features The features that a geographic information system has include advanced analytics, working with huge amounts of information, and the availability of special tools for processing spatial data.

Their main advantages are user-friendliness (data in three-dimensional dimensions is the easiest to perceive), the ability to integrate information accumulated from various sources, and create a single array for collective use.

Then - automatic analysis of geospatial data and a report, the use of decoding of aerial and space surveys, previously created diagrams and terrain plans, which increases the efficiency of application by an order of magnitude. Significant savings in time resources and the ability to create 3D models geographical objects.

Main tasks

GIS functions are a series of operations on:

• data entry ( digital maps are created automatically)
• data management (all of them are stored with the possibility of subsequent processing and use),
• their query and analysis by comparing multiple parameters,
• visualization of received and processed data in the form of interactive maps.

Reports on each object can take the form of a graph, diagram or three-dimensional image.

GIS capabilities

With the help of the GIS system it becomes possible definition in a given territory the presence, quantity and relative location of all existing objects. In addition, it is used, for example, to analyze geospatial data characterizing population density, etc., and determine various changes over time.

With the help of GIS systems, it has become possible to simulate the expected situation regarding, for example, the addition of a new object - a road, a residential area, etc.

GIS - classification

There are several classifications of these systems. If we divide them according to the principle of territory coverage, then each GIS can be classified as global, subcontinental, national, regional, subregional, as well as local or local systems.

Based on the level of management, these systems consist of federal, regional, municipal and corporate.

They are also distinguished by functionality. GIS (the abbreviation is clear to a large number of users) can be either fully functional or specialized, designed to solve specific tasks - for example, viewing data, entering and processing it.

Depending on the subject area, GIS can be classified as cartographic, geological, environmental, and municipal or urban.

Integrated geographic information systems are those in which, in addition to standard functionality, it is possible to subject images to digital processing. Full-scale GIS reproduces data at any scale you choose. Spatiotemporal systems make it possible to operate with information in the past or future.

Where are GIS used?

GIS is a universal tool with a wide range of applications. Which one exactly?

• A typical area of ​​their use is land management, compiling cadastres, calculating areas and setting boundaries of land plots. It was precisely to solve such problems that the first such systems were created.
• Another area is the management of production infrastructure facilities, their accounting, planning, and inventory. Creation and placement of a network of objects for a specific purpose - shops, gas stations, etc.
• Engineering surveys and planning in the field of architecture and construction, solving problems for the development of the territory and optimization of its infrastructure.
• Creation of thematic maps.
• Management of all types of transport - from land to water and air.

Other areas

Nature conservation activities, environmental activities, planning and management of natural resources, environmental monitoring, modeling of environmental processes.

Field of geology and mining. With the help of GIS, it has become possible to calculate mineral reserves based on exploratory drilling samples and modeling the structure of the deposit.

Further development

Since the 70s thanks to government support, experimental projects have appeared on the use of GIS in navigation and waste removal systems, transport traffic, etc.

Since the 80s a period of development on a commercial basis began. The market is filled with masses software, all kinds of applications appeared, the number of users who learned what GIS technologies are exceeded the number of professionals.

In the present period, which can be called custom, thanks to high competition among manufacturers, it has become possible to create thematic groups consumers, holding teleconferences, forming a unified global geostructure.

About the prospects of GIS

A new stage of evolution in the development of GIS can be considered the emergence of geodesign, which is now required everywhere - from the field of land use and natural conservation to planning new infrastructure and construction projects, as well as when maintaining utility networks, etc.

The future belongs to GIS technologies containing the beginnings of artificial intelligence. Modern GIS are the latest computer developments based on the use of space and aerial photography, serving to implement global government programs.

Nowadays, GIS systems are developing at an unprecedented pace and are among the most interesting commercial solutions. In Russia today, about 200 different organizations are engaged in their development and implementation, which allows us to talk about competition with Western manufacturers. It is no longer a secret to anyone that new technologies hold enormous prospects based on the further development of computer information processing tools.

, economy, defense.

Based on territorial coverage, there are global GIS, subcontinental GIS, national GIS, often with state status, regional GIS, subregional GIS and local GIS.

GIS vary subject area information modeling, for example, urban GIS, or municipal GIS, MGIS (urban GIS), environmental GIS (environmental GIS) Template:Nobr; Among them, land information systems received a special name, as they are particularly widespread. The problem orientation of GIS is determined by the tasks it solves (scientific and applied), including resource inventory (including cadastre), analysis, assessment, monitoring, management and planning, and decision support. Integrated GIS, IGIS (integrated GIS, IGIS) combine the functionality of GIS and systems digital processing images (remote sensing data) in a single integrated environment.

Multiscale, or scale-independent GIS (multiscale GIS) are based on multiple, or multiscale representations of spatial objects (multiple representation, multiscale representation), providing graphical or cartographic reproduction of data at any of the selected scale levels based on a single data set with the highest spatial resolution . Spatio-temporal GIS operates with spatio-temporal data. The implementation of geographic information projects (GIS project), the creation of a GIS in the broad sense of the word, includes the stages of: pre-project research (feasibility study), including the study of user requirements (user requirements) and the functionality of the GIS software used, feasibility study, correlation assessment “costs/profits” (costs/benefits); GIS system design (GIS designing), including the pilot-project stage, GIS development; its testing 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 tasks

• Data entry. To be used in a GIS, data must be converted into a suitable digital format(digitized). In modern GIS, this process can be automated using scanner technology, or, for a small amount of work, data can be entered using a digitizer.
• Data manipulation (for example, scaling).
• Data management. In small projects, geographic information can be stored in the form of regular files, and as the volume of information increases and the number of users grows, DBMSs are used to store, structure and manage data.
• Request and analysis of data - obtaining answers to various questions (for example, who is the owner of this land plot? At what distance from each other are these objects located? Where is this industrial zone located? Where is there space for building a new house? What is the main type of soil under spruce forests How will construction affect traffic? new road?).
• Data visualization. For example, presenting data in the form of a map or graph.

GIS capabilities

GIS includes the capabilities of a DBMS, raster and vector graphics editors and analytical tools and is used in cartography, geology, meteorology, land management, ecology, municipal government, transport, economics, defense. GIS allows you to solve a wide range of problems - be it the analysis of such global problems such as overpopulation, pollution of the territory, reduction of forest lands, natural disasters, and solving particular problems, such as searching best route between points, selecting the optimal location for a new office, searching for a house at its address, laying a pipeline on the ground, various municipal tasks.

The GIS system allows:

• determine which objects are located on a given territory;
• determine the location of the object (spatial analysis);
• give an analysis of the distribution density of some phenomenon over the territory (for example, settlement density);
• determine temporary changes in a certain area);
• simulate what will happen when changes are made to the location of objects (for example, if you add a new road).

GIS classification

By territorial coverage:

• global GIS;
• subcontinental GIS;
• national GIS;
• regional GIS;
• subregional GIS;
• local or local GIS.

By management level:

• federal GIS;
• regional GIS;
• municipal GIS;
• corporate GIS.

By functionality:

• fully functional;
• GIS for viewing data;
• GIS for data entry and processing;
• specialized GIS.

By subject area:

• cartographic;
• geological;
• city ​​or municipal GIS;
• environmental GIS, etc.

If, in addition to GIS functionality, the system contains digital image processing capabilities, then such systems are called integrated GIS (IGIS). Multiscale or scale-independent GIS are based on multiple or multiscale representations of spatial objects, providing graphical or cartographic representation of data at any of the selected levels of the scale series based on a single data set with the highest spatial resolution. Spatiotemporal GIS operate with spatiotemporal data.

Areas of application of GIS

• Land management, land cadastres. To solve problems that have a spatial reference, they began to create GIS. Typical tasks are compiling cadastres, classification maps, determining the areas of plots and boundaries between them, etc.
• Inventory, accounting, planning of placement of distributed production infrastructure objects and their management. For example, oil and gas companies or companies that manage the energy network, a system of gas stations, stores, etc.
• Design, engineering surveys, planning in construction, architecture. Such GIS make it possible to solve a full range of problems related to the development of the territory, optimization of the infrastructure of the area under construction, the required amount of equipment, manpower and resources.
• Thematic mapping.
• Management of land, air and water transport. GIS allows you to solve problems of controlling moving objects, provided that given system relations between them and stationary objects. At any time you can find out where the vehicle is located, calculate the load, the optimal trajectory, arrival time, etc.
• Natural resource management, environmental protection and ecology. GIS helps determine the current state and reserves of observed resources, models processes in the natural environment, and carries out environmental monitoring of the area.
• Geology, mineral resources, mining industry. GIS carries out calculations of mineral reserves based on the results of samples (exploration drilling, test pits) with a known model of the deposit formation process.
• Emergencies. With the help of GIS, emergency situations are forecasted (fires, floods, earthquakes, mudflows, hurricanes), the degree of potential danger is calculated and decisions are made to provide assistance, the required amount of forces and resources are calculated to eliminate emergency situations, the optimal routes to the disaster site are calculated, assessment damage caused.
• Military affairs. Solving a wide range of specific problems related to the calculation of visibility zones, optimal routes over rough terrain, taking into account countermeasures, etc.
• Agriculture. Forecasting yields and increasing the production of agricultural products, optimizing their transportation and sales.

Agriculture

Before the start of each growing season, farmers must make 50 critical decisions: what to grow, when to sow, whether to use fertilizers, etc. Any of these can affect yields and the bottom line. Previously, farmers made such decisions based on past experience, tradition, or even conversations with neighbors and other acquaintances. Today, agriculture generates more geo-referenced data than most other industries. Data comes from a variety of sources: vehicle telemetry, weather stations, ground sensors, soil samples, ground observations, satellites and drones. With GIS, agricultural companies can collect, process, and analyze data to maximize resources, monitor crop health, and improve yields.

Transportation and logistics

Moving people and things often presents enormous logistical challenges. Imagine a hospital that wants to provide its patients with... certain time best and fastest route home, or organ local government who wants to organize optimal routes buses and light rail, or a manufacturer that wants to deliver its products as efficiently and economically as possible, or an oil company that plans to lay pipelines. In each of these cases, location data analysis is required to make informed business decisions.

Energy

Energy exploration uses satellite photography, geological maps of the earth's surface, and remote sensing to determine the economic feasibility of mining in a particular area. Energy companies use a huge amount of geographic data, since industrial sensors are now installed everywhere: laser sensors on aircraft, sensors on the surface of the earth when drilling wells, pipeline monitors, etc. Mapping and spatial analysis provide the necessary knowledge to make decisions while meeting regulatory requirements for site selection and localization of resources.

Retail

As consumers increasingly use smartphones and wearable devices, traditional retailers can use geospatial technology to gain a more complete picture of past and present customer behavior. Because geospatial data is not about location, but rather location-related data, such as customer demographics or where people spend the most time in a store. All this data can be used when choosing a location for a store, determining the range of products and their placement, etc.

Defense and intelligence

Geospatial technology has transformed military and intelligence operations in every part of the world where troops are stationed. Commanders, analysts and other professionals need accurate GIS data to solve their problems. GIS helps assess the situation (creates a complete visual representation of tactical information), conduct operations on the ground (shows terrain conditions, altitudes, routes, land cover, objects and populated areas), in the air (transmits weather and visibility data to pilots; directs troops and supplies , gives target designation) and at sea (shows currents, wave heights, tides and weather).

Federal government

Timely and accurate geospatial intelligence is critical to decision-making by federal agencies responsible for safety and security, infrastructure, resource management and quality of life. GIS allows you to organize safety and security with operational support, coordinate defense, response to natural disasters, actions law enforcement agencies, national security agencies and emergency services. In terms of infrastructure, GIS helps manage resources and assets for highways, ports, public transport and airports. Federal agencies also use GIS to better understand the current and historical data needed to manage agriculture, forestry, mining, water and other natural resources.

Local authorities

Local authorities make decisions every day that directly affect residents and visitors. Starting with road repairs and utilities From land valuation to land development, mapping applications are used to analyze and interpret GIS data. In addition, the population and landscape of cities and towns can change dramatically in a relatively short period of time. short time. To adapt to these changes and provide people with the level of service they expect, local governments are making extensive use of modern GIS technology to monitor traffic and road conditions, environmental quality, the spread of disease, the distribution of public utilities (such as electricity, water and sewer), for the management of parks and other public land, and for the issuance of permits for camping, hunting, fishing, etc. .d.

GIS structure

Composition of GIS.

The GIS system includes five key components:

• hardware. This is the computer running the GIS. Currently, GIS operate on various types of computer platforms, from centralized servers to individual or networked desktop computers;
• software. Contains functions and tools necessary for storing, analyzing and visualizing geographic information. To such software products include: tools for entering and manipulating geographic information; database management system (DBMS or DBMS); tools to support spatial queries, analysis and visualization;
• data. Spatial location data (geographic data) and associated tabular data may be collected and produced by the user themselves, or purchased from suppliers on a commercial or other basis. In the process of managing spatial data, a GIS integrates spatial data with other types and sources of data, and can also use the DBMS used by many organizations to organize and maintain the data they have at their disposal;
• performers. GIS users can be both technical specialists who develop and maintain the system, and ordinary employees whom GIS helps solve current everyday affairs and problems;
• methods.

History of GIS

Pioneer period (late 1950s - early 1970s)

Research of fundamental possibilities, border areas of knowledge and technology, development of empirical experience, first major projects and theoretical work.

• The emergence of electronic computers(computer) in the 50s.
• The emergence of digitizers, plotters, graphic displays and others peripheral devices in the 60s.
• Creation of software algorithms and procedures for graphically displaying information on displays and using plotters.
• Creation of formal methods of spatial analysis.
• Creation of database management software.

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.
• Urban waste and garbage removal systems.
• Vehicle movement in emergency situations etc.

Commercial development period (early 1980s - present)

A wide market for various software tools, the development of desktop GIS, expanding the scope of their application through integration with non-spatial databases, the emergence network applications,The emergence of a significant number of non-professional users, ,systems supporting individual datasets on individual computers ,are paving the way for systems supporting enterprise and ,distributed geodatabases.

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 allows the use and even modification of programs, the emergence of user “clubs”, teleconferences, geographically separated but related user groups, an increased need for geodata, the beginning of the formation of the global geographic information infrastructure.

GIS structure

1. Data (spatial data):
   • positional (geographic): the location of an object on the earth's surface.
   • non-positional (attributive): descriptive.
2. Hardware (computers, networks, storage devices, scanner, digitizers, etc.).
3. Software (software).
4. Technologies (methods, procedures, etc.).

56. Geographic information systems (GIS).

The concept of geographic information systems

Geographic information systems (GIS) are automated systems whose main functions are the collection, storage, integration, analysis and graphical visualization in the form of maps or diagrams of spatiotemporal data, as well as associated attribute information about objects presented in GIS.

GIS emerged in the 1960–70s. at the intersection of information processing technologies in database management systems and visualization of graphic data in computer-aided design (CAD) systems, automated map production, and network management. Intensive use of GIS began in the mid-90s. XX century At this time, powerful and relatively cheap personal computers appeared, and software became more accessible and understandable.

The data sources for creating GIS are:

Cartographic materials (topographic and general geographical maps, maps of administrative-territorial divisions, cadastral plans, etc.). Since the data obtained from maps is spatially referenced, they are used as a base GIS layer;

Remote sensing data (RSD), primarily materials received from spacecraft and satellites. In remote sensing, images are obtained and transmitted to Earth from imaging equipment located in different orbits. The resulting images are distinguished by different levels of visibility and detail in displaying objects of the natural environment in several spectral ranges (visible and near-infrared, thermal infrared and radio ranges). Thanks to this, a wide range of environmental problems are solved using remote sensing. Remote sensing methods also include aerial and ground surveys, and other non-contact methods, such as hydroacoustic surveys of the seabed topography. Materials from such surveys provide both quantitative and qualitative information about various objects of the natural environment;

Results of geodetic measurements on the ground, performed by levels, theodolites, electronic total stations, GPS receivers, etc.; - data from state statistical services for a variety of sectors of the national economy, as well as data from stationary measuring observation posts (hydrological and meteorological data, information on environmental pollution, etc.).

Literary data (reference publications, books, monographs and articles containing a variety of information on certain types of geographical objects). In GIS, only one type of data is rarely used; most often it is a combination of various data for any territory.

Classification of geographic information systems.

GIS systems are developed and used to solve scientific and applied problems of infrastructure design, urban and regional planning, rational use of natural resources, monitoring environmental situations, as well as for taking prompt measures in emergency situations, etc. Many problems arising in life have led to creation of various GIS, which can be classified according to the following criteria:

By functionality: - full-featured general-purpose GIS;

Specialized GIS, 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 its construction:

Closed systems do not have expansion capabilities; they are capable of performing only the set of functions that are clearly defined at the time of purchase; - open systems are distinguished by ease of adaptation and expansion capabilities, since they can be completed by the user himself using a special device (built-in programming languages).

According to spatial (territorial) coverage, GIS are divided into global (planetary), national, regional, local (including municipal).

By problem-thematic orientation - general geographic, environmental and environmental management, sectoral (water resources, forestry, geological, tourism, etc.).

According to the method of organizing geographic data - vector, raster, vector-raster GIS.

Basic components of geographic information systems.

The main components of GIS include: technical (hardware) and software, information support.

Technical means is a set of hardware used in the operation of GIS. These include a workstation (personal computer), information input/output devices, data processing and storage devices, and telecommunications.

The workstation is used to manage the operation of the GIS and perform data processing processes based on computational and logical operations. Modern GIS are capable of quickly processing huge amounts of information and visualizing 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 from electronic surveying instruments, using a digitizer or scanner, or using photogrammetric instruments.

Devices for processing and storing data are integrated into the computer system unit, which includes a central processor, RAM, storage devices ( hard drives, portable magnetic and optical storage media, memory cards, flash drives, etc.). Data output devices – monitor, plotter, plotter, printer, which provide a visual representation of the results of processing spatiotemporal data.

Software tools– software for implementing GIS functionality. It is divided into basic and application software.

Basic software includes: operating systems (OS), software environments, network software, database management systems, as well as modules for managing data input and output, a data visualization system and modules for performing spatial analysis.

Application software includes software designed to solve specialized problems in a specific subject area. They are implemented in the form of separate modules (applications) and utilities (auxiliary tools).

Information support– a set of information arrays, systems of coding and classification of information. A feature of storing spatial data in GIS is its division into layers. The multi-layer organization of an electronic map, with a flexible layer management mechanism, allows you to combine and display much more information than on a regular map.

(Everything is usual here. Point by point.)

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.

Any geographic information contains information about spatial location, be it reference to geographic or other coordinates, or links to an address, postal code, electoral or census district, parcel or forest identifier, road name, 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, 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 X,Y coordinates. The location of a point (point object), for example a borehole, is described by a pair of coordinates (X,Y). Linear objects, 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 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 similar to a scanned map or picture. Both models have their advantages and disadvantages. Modern GIS can work with both vector and raster models.

Problems that GIS solves. A general purpose GIS typically performs five data activities (tasks), among other things: 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 to computer files called digitization. In modern GIS, this process can be automated using scanner technology, which is especially important for large projects, or, for small jobs, data can be entered using a digitizer. 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 in 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 manipulating spatial data and extracting 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) for storing, structuring and managing data, or 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 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 receive answers to 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 more complex queries that require additional analysis (Where are there places for construction new house? What is the main type of soil under the spruce forests? How will the construction of a new road affect traffic?). Queries can be set either by simply clicking on a specific object or using advanced analytical tools. Using GIS, you can identify and set search patterns and play out “what will happen if…” scenarios. Modern GIS have many powerful tools for analysis, among them two are the most significant: proximity analysis and overlap 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 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 management building of this oil and gas production unit? 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 unite physically. Overlay, or spatial aggregation, allows data on soils, slope, vegetation and land ownership to be integrated with land tax rates, for example.

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 and tables, photographs and other means, for example, 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 technology. global positioning(GPS).

Desktop mapping systems use cartographic representation to organize the user's 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 younger models of UNIX workstations.

CAD systems are capable of design 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 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 techniques are an art and scientific direction to take 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 processing, analysis and visualization capabilities for the resulting images. Due to the lack of sufficiently powerful data management and analysis tools, the corresponding systems can hardly be classified as 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, which is why many GIS have built-in DBMS support. These systems do not have tools for analysis and visualization similar to GIS.

geographic information system mapping