The concept of gis. Abstract on the topic “Geoinformation systems

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 understanding and highlighting the main factors and causes, as well as their possible consequences, with planning 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, at the sight of the possibilities of GIS, his 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 hold.

Performers. Widespread use of GIS technology is impossible without people who work with software products and develop plans for using them to solve real-world 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 matters 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 highly 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 situations 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, data on soils, slope, vegetation and land ownership to be integrated 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, which is why 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 replenished 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

Review:

Just as we use a word processor to work with words and prepare documents, we can use GIS application for working with sets spatial information on the computer. GIS stands for " Geographic Information System" Any GIS consists of the following interconnected components:

• Digital data– geographic information that you view and analyze using hardware and software.
• Hardware– computers used to store, display and process data.
• Software– computer programs that run on hardware and allow you to work with digital data. The software that is part of a geographic information system is called a GIS application.

With a GIS application, you can open digital maps on your computer, create new spatial information and add it to the map, prepare printable maps to suit your needs, and perform spatial analysis.

Below is a simple example of using GIS. Imagine that a healthcare company noted the place of residence and date of visit for each patient being treated:

The table shows that measles cases occur in January and February. The location of each patient's home is noted in the table as latitude and longitude. Using this data in a GIS application, we can quickly learn more details about disease patterns:

Figure 1: Example showing patient records in a GIS application. It is easy to see that measles patients live close to each other.

More about GIS:

GIS is a relatively new field of knowledge, dating back to the 1970s. Previously, computerized systems were only available to large companies and universities with expensive equipment. Today, anyone with a personal computer or laptop can use GIS applications. Over time, GIS applications have also become easier to use - where previously there was a lengthy learning curve, now anyone can start using GIS for their day-to-day needs. As described above, GIS are more than just software; they cover all aspects of the management and use of digital geodata. In this tutorial, we will talk primarily about GIS applications.

What is a GIS application (software)?

You can see an example of what it looks like GIS application, above in Figure 1. GIS applications are computer programs with a graphical user interface controlled by a mouse and keyboard. The application contains a main menu at the top of the window (File, Editing, etc.), which, when clicked with the mouse, shows the corresponding command panels. Commands provide a way to tell the GIS application exactly what you want to do. For example, you can use the menu to send a command to add a new layer to the display list.

Toolbars(rows of small icons with commands that can be launched with a mouse click) are usually located directly below the main menu and provide quick access to the most frequently used functions.

Figure 3: Toolbars provide quick access to frequently used functions. Hovering over an icon usually
calls a tooltip with a description of the corresponding function.

A commonly used feature of a GIS application is displaying cartographic layers. Map layers are stored as files on disk or within a database. Typically, each map layer corresponds to specific real-world features, such as a road layer representing a road network.

When you open a layer in a GIS application, it appears in map areas.

The map area shows a graphical representation of your layer. When you add more than one layer to a map, the layers overlap each other. Figures 4-7 show a map with several layers added. An important function of the map is navigation, which includes zooming in, out, and moving the map.

Figure 4: Cities layer added to the map.	Figure 5: Schools layer added to the map.
Figure 6: Railroad layer added to the map.	Figure 7: Rivers layer added to the map.

Unlike paper maps, maps opened in GIS applications can be modified after they are created. You can change the shape and color of map layer legends. For example, if we take the map from Figure 7 and change its legend, it will completely change its appearance, as shown in Figure 8. Legend plays an important role in how we read maps, and they are quick and easy to change in a GIS. application.

Another common feature of GIS applications is map legend. The map legend contains a list of map layers loaded into the GIS application. Unlike a paper map legend, a legend in a GIS application provides the ability to rearrange layers, hide them, and create layer groups. By dragging layers with the mouse, you can change the order in which they are drawn on the electronic map. In Figures 9 and 10, the map legend is shown on the left side of the GIS application window. By changing the layer order, rivers appear on top of roads, rather than the other way around.

Installing a GIS application on your computer:

There are many GIS applications available. Some include advanced, highly specialized tools and cost tens of thousands of dollars per license. At the same time, there are a number of free GIS applications. The choice of application depends on what finances you have and on your personal preferences. The application used in this tutorial is Quantum GIS, also known as QGIS. Quantum GIS is completely free and you can copy it and share it with as many people as you like. If you received this manual in printed form, a copy of QGIS should accompany it. Otherwise, you can visit http://qgis.org and download a free copy.

Geodata:

Now we know what GIS and GIS applications are, let's talk about geodata. Data is a certain information. The information we use in GIS is usually georeferenced. Recall the above example of healthcare enterprise data. To store patient records, a table of the following type has been created:

The longitude and latitude columns contain geographic (spatial) data. The disease name and date are non-spatial data. A common function of GIS is to establish a connection between the first and second. In essence, a GIS application can store a wealth of information about each location, unlike a paper map, which has limited capabilities. For example, the gender and age of patients can be easily entered into the table in question. By adding a patient location layer to a GIS application, you can set its display to be based on age or disease type, or another attribute of the patient you want, whereas a paper map will only show one attribute. Thus, with a GIS application, we can change the appearance of our map based on the non-spatial information associated with specific locations.

GIS systems work with numerous types of data. Vector data are stored in computer memory in the form of sequences of coordinate pairs (X,Y). Vector data is used to represent points, lines, and areas (polygons). Figure 11 shows the different types of vector data exposed in a GIS application. Vector data will be discussed in more detail later in this tutorial.

Raster data stored as a grid of values. Numerous satellites orbit the Earth, and the photographs they produce are raster images that can be viewed in a GIS application. One of the main visible differences between raster data and vector data is that when you zoom too close to a raster image, it consists of squares (see Figures 12 and 13). Each of these squares is a separate cell in the data grid that makes up the raster image. Raster data will be discussed in more detail later in this tutorial.

Figure 12: Satellite image - typical example raster data. This photo shows mountains.		Figure 13: The same data, but this time with more approaching. The grid structure of the image is visible.

What have we learned?

Let's consolidate the material we've learned:

• GIS is a system of hardware, software and geodata.
• GIS application allows you to view geodata and is an important part of the GIS.
• A GIS application typically includes main menu, toolbars, map area And legend.
• Geographic data used in a GIS application is raster And vector.
• Geographical data can be combined with non-spatial data.

Try it yourself!

Below are some examples of practical tasks for your students:

• Describe the concept of GIS to your students, as done in this manual. Ask them to name 3 reasons why using GIS is better than using paper maps. Below are sample answers:
  • A GIS application allows you to create many different maps based on the same data;
  • GIS is an excellent visualization tool that allows you to look at your map at different scales;
  • Paper maps require a lot of work to create and even viewing them takes a long time. GIS can store very large amounts of data and makes the process of finding desired locations simple and fast.

• Consider how raster data from satellites is used. For example:
  • During natural disasters, raster data can show affected areas. For example, a recent satellite image taken during a flood helps locate people whose homes were submerged.
  • Sometimes people cause harm to the environment, such as storing dangerous chemicals that kill plants and animals. Using satellite data, we can monitor such problems.
  • City planners use raster data from satellites to help identify new developments and help plan infrastructure.

If you don't have a computer:

Many of the topics covered in this manual can be visualized using a projection device and transparencies because... they depict a similar overlay of layers of information. However, a proper understanding of GIS is always achieved better using a computer.

GIS (DoubleGIS Barnaul)

It is quite difficult to give an unambiguous, brief definition of this phenomenon. Geographic Information System (GIS)- this is an opportunity for a new look at the world around us. Without generalizations and images, GIS is a modern computer technology for mapping and analyzing objects in the real world, as well as events occurring on our planet. This technology combines traditional database operations, such as query 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 opportunities for its use in a wide range of tasks related to the analysis and forecast of phenomena and events in the surrounding world, with understanding and highlighting the main factors and causes, as well as their possible consequences, with planning strategic decisions and the ongoing consequences of the actions taken. Mapping and geographic analysis are not entirely new. However, GIS technology provides a new, more modern, more efficient, convenient and faster approach to analyzing problems and solving problems facing humanity in general, and a specific organization or group of people in particular. It automates the analysis and forecast procedure. Before the use of GIS, only a few possessed the art of summarizing and fully analyzing geographic information in order to make informed optimal decisions based on modern approaches and tools. GIS is now a multi-million dollar industry involving hundreds of thousands of people around the world. GIS is taught 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, reduction of forest land, natural disasters, or in solving particular problems, such as finding the best route between points, selecting the optimal location for a new office, searching houses at his address, laying a pipeline in the area, various municipal tasks. Based on territorial coverage, there are global GIS, subcontinental GIS, national GIS, often with state status, regional GIS, subregional GIS and local or local GIS.

GIS differ in the subject area of ​​information modeling, for example, urban GIS, or municipal GIS, MGIS (urban GIS), environmental GIS (environmental GIS), etc.; Among them, land information systems received a special name, as 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 digital image processing systems (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.

History of GIS

Initial 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 (computers) in the 50s.
• The advent of digitizers, plotters, graphic displays and other 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.
• Movement of vehicles in emergency situations, etc.

Commercial development period (early 1980s - present)

A wide market for a variety of software, the development of desktop GIS, the expansion of their scope of application through integration with non-spatial databases, the emergence of network applications, the emergence of a significant number of non-professional users, systems that support individual data sets on individual computers, pave the way for systems that support corporate and distributed geodatabases.

User period (late 1980s - present)

Increased competition among commercial producers of geoinformation 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.

How GIS works

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 mapping of real-life situations 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 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 of X,Y coordinates. 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 watersheds, 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.

GIS layers

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

Spot

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

Linear

These objects can be abstracted to a broken or smooth line, such as rivers, roads, or pipelines.

Polygonal or area

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

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

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

Images

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

Mesh models

These are structural maps and parameter maps. Initially, such models were based on a rectangular grid, where the Z (parameter) value was indicated at the grid nodes.

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

A spline mesh differs from a regular mesh in that its surface is perfectly smooth, which is more natural for most models. Fracture meshes contain additional segments to simulate a smooth fracture. On a conventional mesh model, the gap appears in steps. Grid models are also called contour maps.

Special types of layers

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

GIS Data Tables

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

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

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

Formation of layers

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

Coordinates

Everyone knows that the earth is round, and the map is flat, and the surface of the ball cannot be turned onto a plane without deformation. For this reason, projections are used in cartography. Projections are rules and formulas for transforming one coordinates into others. A commonly used conversion is from spherical (geographic) coordinates to rectangular coordinates (map coordinates). Projections can be equal area or equiangular, that is, they preserve the area of ​​objects or angles. Sometimes a projection can distort both, minimizing distortion altogether. For our country, the standard transformation system is the “42nd year” coordinate system. The “42nd year” system divides the territory of the globe into 60 zones, 6 degrees each. The Tyumen region, for example, is located within the 12th, 13th and 14th zones. "42nd year" is an equal area projection. GIS are designed in such a way that they can store data in one coordinate system and display it in another. Therefore, it is necessary not to get confused with which coordinate system the data is stored in and in which it is displayed on the map. To reduce confusion with projections, Isoline only supports two source data options:

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

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

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

Projection not set. Real coordinates are "polyconical", displayed coordinates are rectangular.

Projection not set. Real coordinates are degrees, displayed coordinates are rectangular.

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

As you can see from the pictures, the top two suit us quite well, but the third and fourth do not. The third drawing, in fact, is quite correct, but the projection is not indicated, and therefore we see the image “as is”, in degrees. In the fourth picture, we tried to display a polygon whose data is not degrees in a “polyconical” projection and the system did not understand us. From this we can draw the following conclusion: it is impossible to set a projection for rectangular coordinates, since in this case the transformation formulas are applied to them a second time, and the image turns out to be incorrect.

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

Rectangular coordinates

"polyconical", without display adjustments.

Mollweide coordinate system.

polyconical", with display adjustments.

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

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 into computer files is 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 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 properties are at a scale of 1:10,000). For joint processing and visualization, it is more convenient to present all data on a single scale. GIS technology provides different ways to manipulate spatial data and 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) 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 which two are the most significant: proximity analysis and overlay analysis. To analyze the proximity of objects relative to each other, GIS uses a process called buffering. It helps answer questions like: How many houses are within 100 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 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 and tables, photographs and other means, for example, multimedia.

Technologies related to GIS

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 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

CAD systems capable of project drawings and plans of buildings and infrastructure. To combine into a single structure, they use a set of components with fixed parameters. They are based on a small number of rules for combining components and have very limited analytical functions. Some CAD systems 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 the art and science of taking measurements of the earth's surface using sensors such as various cameras on board aircraft, global positioning system receivers, or other devices. These sensors collect data in the form of images and provide specialized 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 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 do not have tools for analysis and visualization similar to GIS.

What GIS can do for you

Perform spatial queries and analysis

GIS's ability to search databases and perform spatial queries has saved many companies millions of dollars. GIS helps reduce the time it takes to respond to customer requests; identify areas suitable for the 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 certain area that have slate roofs, three rooms and 10-meter kitchens, and then provide more detailed descriptions of these 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 certain distance from a certain highway, forested area or place of work.

Improve integration within the organization

Many organizations using GIS have discovered that one of its main benefits lies in the new opportunities to improve the management of their organization and its resources by geographically aggregating existing data and allowing it to be shared and modified in a coordinated manner across different departments. The ability to share and constantly expand and correct the database by different structural units allows you to increase the efficiency of both each unit 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 of the timing of expected shutdowns or interruptions in water supply.

Make more informed decisions

GIS, like other information technologies, confirms the well-known adage that better information leads to better decisions. However, GIS is not a tool for issuing decisions, but a tool that helps speed up and increase the efficiency of the decision-making procedure, providing answers to queries and functions for analyzing spatial data, presenting analysis results in a visual and easy-to-read form. GIS helps, 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 textual 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 analyzing the available heterogeneous data. You can quickly consider several solution options and choose the most effective and efficient one.

Creating maps

Maps have a special place in GIS. The process of creating maps in GIS is much 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. Based on such databases, it is possible to create maps (in electronic form or as hard copies) for 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 existing data can be adjusted as necessary. In large organizations, the created topographic database can be used as a basis by other departments and divisions, while quickly copying data and sending it over local and global networks is possible.

GIS in Russia

The most widely used foreign systems in Russia are: software product ArcGIS companies ESRI, product family GeoMedia corporations Intergraph And MapInfo Professional companies Pitney Bowes MapInfo.

Among domestic developments, the company's GIS Map 2008 program has become widespread CJSC KB "Panorama".

Other software products of domestic and foreign development are also used: GIS INTEGRO, M.G.E. corporations Intergraph(uses MicroStation as graphics core), IndorGIS, STAR-APIC, DoubleGIS , Mappl, Geographer GIS, 4geo etc.

FEDERAL AGENCY FOR EDUCATION

State educational institution of higher professional education

"St. Petersburg State Polytechnic University"

INSTITUTE OF MANAGEMENT AND INFORMATION TECHNOLOGY

(branch) of St. Petersburg State Polytechnic University in Cherepovets

(IMIT SPbSPU)

Department of Management

Abstract on the topic “Geoinformation systems”

Completed by student gr. 0.182

Teacher Shutikova

Cherepovets

INTRODUCTION

A Geographic Information System - or GIS - is a computer system that allows data to be displayed on an electronic map. Maps created using GIS can easily be called new generation maps. GIS maps can be used to map not only geographic, but also statistical, demographic, technical and many other types of data and apply various analytical operations to them. GIS has the unique ability to reveal hidden relationships and trends that are difficult or impossible to notice using traditional paper maps. We see a new, high-quality meaning of our data, and not a mechanical set of individual parts.

An electronic map created in GIS is supported by a powerful arsenal of analytical tools, rich tools for creating and editing objects, as well as databases, specialized scanning devices, printing and other technical solutions, Internet tools - and even satellite images and information from satellites.

The GIS system includes five key components:

· hardware. This is the computer running the GIS. Today, GIS operate on various types of computer platforms, from centralized servers to stand-alone or networked desktop computers;

· software . Contains functions and tools necessary for storing, analyzing and visualizing geographic information. 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.

2. 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 (computers) in the 50s.

· The emergence of digitizers, plotters, graphic displays and other 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.

· Movement of vehicles in emergency situations, etc.

Commercial development period (early 1980s - present)

A wide market for a variety of software, the development of desktop GIS, the expansion of their scope of application through integration with non-spatial databases, the emergence of network applications, the emergence of a significant number of non-professional users, systems that support individual data sets on individual computers, pave the way for systems that support corporate and distributed geodatabases.

User period (late 1980s - present)

Increased competition among commercial producers of geoinformation 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 in Russia

The most widely used software products in Russia are ArcGIS and ArcView from ESRI, the GeoMedia family of products from Intergraph Corporation, and MapInfo Professional from Pitney Bowes MapInfo.

Other software products of domestic and foreign development are also used: Bentley's MicroStation, IndorGIS, STAR-APIC, Zulu, DoubleGIS, etc.

3. Prospects for GIS

GeoDesign is an evolutionary stage in the development of GIS. It is very important for the process of planning and development of territories, especially in the field of land use and environmental protection, but is widely in demand in almost all other applied and scientific fields. For example, this methodology will be widely used in the retail trade to open new stores and close old ones, by civil engineers to place infrastructure such as roads in the most suitable locations, by organizations maintaining utility networks, in agriculture, forestry and water management, by power departments, energy companies, military and many others. This approach will further enhance the importance of GIS, moving it beyond a simple description of the world “as it is” towards the development and implementation of concepts for creating the future, integrating geographic (spatial) thinking into all areas of our activities.

The future belongs to GIS technologies with elements of artificial intelligence based on the integration of GIS and expert systems. The advantages of such a symbiosis are quite obvious: the expert system will contain the knowledge of an expert in a particular field and can be used as a decision or advisory system.

The current status of new computer geotechnologies is determined by large government programs and foreign investments aimed at the widespread use of aerial and satellite images, digital maps, and database visualization.

The urban GIS of the future will make it possible not only to receive semantic information about objects on the map upon request, but also to predict the development of the territory, allow the city leadership to play out options for policy decisions, the possible construction of a new city district, etc. At the same time, the GIS, together with a simulation modeling system, will be able show city planners how loads will be redistributed in city utility networks, the power of traffic flows, how the price of real estate will change depending on the construction of additional highways or the construction of a new shopping center in a particular area.

Conclusion

At the moment, GIS systems are one of the fastest growing and most interesting in terms of commercialization, with their user-friendly interface and the huge amount of information they contain, making them indispensable in an ever-accelerating world.

At the moment, in Russia, about 200 organizations are engaged in the development and implementation of GIS systems; the creation of a land cadastre will allow us to build other, subject-oriented maps based on its maps and supplement them with appropriate attribute content, which will allow our systems to compete with Western models.

With the greater development of mobile access to the network through various devices, GIS systems using satellite images coupled with three-dimensional modeling will allow even an ordinary user to navigate any terrain without any problems and receive all the necessary information from these systems simply by asking a question.

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 characterized 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 multilayer organization of an electronic map, with a flexible layer management mechanism, allows you to combine and display a much larger amount of information than on a regular map.

(Everything is usual here. Point by point.)