Geographic Information System (GIS) is a subject developed with the development of geographic science, computer technology, remote sensing technology and information science. In the history of computer development, in the history of computer development, the emergence of computer-aided design technology (CAD) enabled people to use computers to process data like graphics. One of the signs of graphic data is that graphic elements have clear position coordinates, and there are various topological relationships between different graphics. Simply put, topological relationship refers to the spatial position and connection relationship between graphic elements. Simple graphic elements, such as points, lines, polygons, etc. Points have coordinates (x, y); A line can be regarded as consisting of countless points, and its position can be expressed as a series of coordinate pairs (x 1, y 1), (x2, y2), ... (xn, yn); A polygon on a plane can be considered as a range formed by closed curves. There are various relationships between graphic elements, such as points on lines or polygons, lines passing through polygons and so on. In practical application, a geographic information system has to manage a large number of complex data, including thousands of polygons, thousands of lines and thousands of points, and also calculate and manage various complex spatial relationships among them.
Geographic Information System (GIS) is the integration of computer hardware, software, geographic data and system administrators to efficiently acquire, store, update, operate, analyze and display any form of geographic information.
Geographic information system technology is widely used in almost all industries, such as agriculture, forestry, land resources, geology and mineral resources, military affairs, transportation, surveying and mapping, water conservancy, radio and television, communication, electric power, public security, community management, education, energy and so on, and is entering people's daily work, study and life.
The main computer hardware of geographic information system is workstation and microcomputer. The main computer operating system software of GIS includes UNIX, Windows9X, Windows NT, Windows2000, Macintosh, etc.
The main computer application softwares of GIS are ARC/INFO, MGE, GeoMedia, GenaMap, MapInfo, AutoDesk Map, ArcView, MapObjects, MapX, Maptitude, MapGIS, GeoStar, MapEngine, etc.
The main geographic data scales of GIS are1:4 million, 1: 1 10,000,1:250,000,1:50,000, 1: 1. Basic geographic data include digital line drawing (DLG), digital raster drawing (DRG), digital orthophoto drawing (DOQ) and digital elevation model (DEM).
Related technologies of GIS geographic information system
GIS is closely related to several other information systems, but it is different from other information systems because of its ability to process and analyze geographic data. Although there are no hard and fast rules to classify these information systems, the following discussion is helpful to distinguish GIS from desktop mapping, computer-aided design CAD, remote sensing, DBMS and GPS technology.
Desktop drawing
Desktop mapping systems use maps to organize data and user interaction. The main purpose of this system is to generate maps: maps are databases. Most desktop mapping systems only have limited functions of data management, spatial analysis and personalization. Desktop drawing system runs on desktop computers, such as PC, Macintosh and small UNIX workstations.
Computer aided design
Computer aided design (CAD) system promotes the design and planning of architecture and capital construction. This design requires assembling parts with inherent characteristics to produce the whole structure. These systems need some rules to indicate how to assemble these components, and they have very limited analysis ability. CAD system has been extended to support map design, but tools for managing and analyzing large-scale geographic databases are limited.
Remote sensing and global positioning system
Remote sensing is a science and technology that uses sensors to measure the earth, such as cameras on airplanes, global positioning system (GPS) receivers or other equipment. These sensors collect data in the form of images and provide special functions for using, analyzing and visualizing these images. Because it lacks powerful geographic data management and analysis functions, it can't be called a real GIS.
DBMS database management system
Database management system specializes in how to store and manage all kinds of data, including geographic data. DBMS optimizes data storage and search, and many GIS rely on it to achieve this goal. Compared with GIS, they have no tools for analysis and visualization.