Introduction
Geographic Information Systems and free software are two amazing things created by the 20th century.
The amount of information that exists in the modern world cannot be compared with that which was received in past centuries. GIS makes it possible to process, organize, analyze and visualize a colossal amount of information.
Open source software is one of the most interesting technological phenomena of the present time. Open source GIS software is rapidly evolving and is even superior in some characteristics to commercial products and has a number of advantages. But, in terms of distribution, they are incomparably lagging behind. What are the reasons?
GEOGRAPHIC INFORMATION SYSTEMS.
1.1. Introduction to GIS
The emergence of geographic information systems dates back to the early 60s of the XX century. It was then that the prerequisites and conditions appeared for informatization and computerization of the spheres of activity associated with the modeling of geographic space and the solution of spatial problems. Their development is associated with research carried out by universities, academic institutions, defense departments and mapping services. For the first time the term “geographic information system” appeared in the English-language literature and was used in two variants, such as the geographic information system and the geographical information system, very soon it also received an abbreviated name (abbreviation) GIS. A little later, this term penetrated into the Russian scientific lexicon, where it exists in two equivalent forms: initial complete in the form of a “geographic information system” and reduced in the form of a “geographic information system”. The first of them very soon became official ceremonial, and the quite reasonable striving for brevity in speech and texts reduced the last of them to the abbreviation “GIS”.
Geographic information system is a software and hardware complex designed to collect, manage, analyze and display spatially distributed information. GIS is not only and not so much information systems for geography as information systems with geographically organized information. In the simplest form, geographic information systems are a combination of conventional databases (attributive information) with electronic maps, that is, powerful graphical tools.
The term is also used in a narrower sense – GIS as a tool (software product) that allows users to search, analyze and edit digital maps, as well as additional information about objects, such as building height, address, number of residents.
The main idea of GIS is to link data on a map and in a database. GIS is also an analytical tool for working with any geo-referenced information. In principle, GIS can be viewed as an extension of the concept of databases. In this sense, GIS actually represents a new level and way of integrating and structuring information. GIS offers a completely new way of developing cartography. The main disadvantages of conventional cards are being overcome – their static nature and limited capacity as an information carrier. In recent decades, paper maps have become unreadable due to the overload of information. GIS provides information visualization control. It becomes possible to display (on the screen, on a hard copy) only those objects or their sets that are of interest to us at the moment. In fact, the transition from complex complex maps to a series of interconnected private maps is under way. This improves the structuredness of information, and, consequently, increases the efficiency of its processing and analysis. In GIS, the map comes to life and becomes a truly dynamic object in the sense of:
- · scalability;
- · transformation of cartographic projections;
- · varying the object composition of the map;
- · the ability to poll multiple databases in real time via the map;
- · changing the way objects are displayed (color, line type, etc.), including the definition of symbology through attribute values, that is, synchronization of visualization with changes in databases;
- · ease of making any changes.
1.2. Main components of GIS
Technical support
Technical support is a set of hardware used in the operation of a GIS: a workstation or personal computer (PC), information input-output devices, data processing and storage devices, telecommunication facilities.
A workstation or PC is the core of any information system and is designed to control the work of GIS and perform data processing processes based on computational or logical operations. Modern GIS is able to quickly process huge amounts of information and visualize the results.
Data entry is carried out using various technical means and methods: directly from the keyboard, using a digitizer or scanner, through external computer systems. Spatial data can be obtained by electronic geodetic instruments, directly using a digitizer and a scanner, or from the results of processing images on analytical photogrammetric devices or digital photogrammetric stations.
Devices for processing and storing data are concentrated in a system unit, which includes a central processor, random access memory, external storage devices and a user interface.
Data output devices must provide a visual representation of the results, primarily on a monitor, as well as in the form of graphic originals obtained on a printer or plotter (plotter); in addition, it is mandatory to export data to external systems.
Software
Software – a set of software tools that implement the functionality of GIS, and program documents required for their operation.
Structurally, GIS software includes basic and applied software tools.
Basic software tools include: operating systems (OS), software environments, network software and database management systems. Operating systems are designed to manage computer resources and the processes that use these resources. Currently the main operating systems are Windows and Unix.
Any GIS works with data of two types of data – spatial and attributive. To maintain them, the software must include a database management system for those and other data (DBMS), as well as modules for controlling data input and output tools, a data visualization system and modules for performing spatial analysis.
Application software tools are designed to solve specialized problems in a specific subject area and are implemented as separate applications and utilities.
Information Support
Information support – a set of information arrays, information coding and classification systems. Information support consists of implemented solutions for the types, volumes, placement and forms of information organization, including the search and assessment of data sources, a set of data entry methods, database design, maintenance and meta-maintenance. The peculiarity of storing spatial data in GIS is their division into layers. The multilayer organization of an electronic map, with a flexible layer management mechanism, allows you to combine and display a much larger amount of information than on a conventional map. Position data (geographic data) and associated tabular data can be prepared by the user or purchased. A spatial data infrastructure is essential for this data exchange.
The spatial data infrastructure is determined by regulatory documents, mechanisms for organizing and integrating spatial data, as well as their availability to different users. A spatial data infrastructure includes three essential components: basic spatial information, spatial data standardization, metadata databases, and a data exchange mechanism.
1.3. The tasks that GIS solves
General-purpose GIS, among other things, usually performs five procedures (tasks) with data:
- 1. input,
- 2. manipulation,
- 3. control,
- 4. query and analysis,
5. visualization.
Input.
For use in GIS, the data must be converted to a suitable digital format. The process of converting data from paper maps into computer files is called digitization. In gis courses melbourne, this process can be automated using scanner technology, which is especially important when carrying out large projects, or, with a small amount of work, data can be entered using a digitizer. Many data have already been translated into formats that are directly perceived by GIS packages.
Manipulation.
Often, to complete a specific project, the existing data needs to be additionally modified in accordance with the requirements of your system. For example, geographic information can be at different scales (street centerlines are at a scale of 1: 100,000, census district boundaries are at a scale of 1: 50,000, and residential properties are at a scale of 1: 10,000). For joint processing and visualization, it is more convenient to present all data on a single scale. GIS technology provides different ways to manipulate spatial data and highlight the data needed for a specific task.
Control.
In small projects, geographic information can be stored as regular files. But with an increase in the amount of information and an increase in the number of users for storing, structuring and managing data, it is more efficient to use database management systems (DBMS), that is, special computer tools for working with integrated data sets (databases). In GIS, it is most convenient to use a relational structure in which data is stored in tabular form. In this case, common fields are used to link tables. This simple approach is flexible enough and is widely used in many GIS and non-GIS applications.
Query and analysis.
If you have GIS and geographic information, you can get answers to simple questions (Who is the owner of this land plot? At what distance are these objects from each other? Where is this industrial zone located?) And more complex queries that require additional analysis (Where are places for construction a new house? What is the main soil type under spruce forests? How will the construction of a new road affect traffic?). Queries can be set both by a simple mouse click on a specific object, and with the help of advanced analytical tools. With the help of GIS, one can identify and set patterns for search, play scenarios like “what will happen if…”.
Visualization.
For many types of Spatial Services, the end result is the presentation of the data in the form of a map or graph. A map is a very efficient and informative way of storing, presenting and communicating geographic (georeferenced) information. Previously, maps were created for centuries. GIS provides amazing new tools that expand and develop the art and scientific foundations of cartography. With its help, the visualization of the maps themselves can be easily supplemented with reporting documents, three-dimensional images, graphs and tables, photographs and other means, for example, multimedia.