GIS Overview and Components
GIS, or Geographic Information System, is a technical system based on a geospatial database that, with the support of computer hardware and software, applies the theories of systems engineering and information science to scientifically manage and comprehensively analyze geographically referenced data with spatial connotations, so as to provide the information required for management, decision-making, and other purposes. In simple terms, GIS is a technical system for the integrated processing and analysis of geospatial data. It is based on surveying and mapping, uses databases as the data source for data storage and usage, and employs computer programming as the platform for real-time global spatial analysis. As an important tool, technology, and discipline for acquiring, storing, analyzing, and managing geospatial data, Geographic Information Systems have gained widespread attention and rapid development in recent years.
From an application perspective, a Geographic Information System consists of five components: hardware, software, data, personnel, and methods. Hardware and software provide the environment for GIS construction; data is an important content of GIS; methods provide solutions for GIS construction; and personnel are the key and dynamic factor in system construction, directly influencing and coordinating the other components.
Hardware mainly includes computers and network equipment, storage devices, and peripheral equipment for data input, display, and output.
Software mainly includes the following categories: operating system software, database management software, system development software, GIS software, and so on.
GIS-Related Technologies
GIS is closely related to several other information systems, but it is distinguished from them by its ability to process and analyze geographic data. Although there are no hard-and-fast rules for classifying these information systems, the following discussion can help distinguish GIS from desktop mapping, computer-aided design (CAD), remote sensing, DBMS, and GPS technologies.
Desktop Mapping
Desktop mapping systems use maps to organize data and user interaction. The primary purpose of such systems is to produce maps: the map is the database. Most desktop mapping systems have only very limited data management, spatial analysis, and customization capabilities. Desktop mapping systems operate on desktop computers, such as PCs, Macintoshes, and small UNIX workstations.
Computer-Aided Design (CAD)
Computer-aided design (CAD) systems facilitate the design and planning of buildings and infrastructure. Such design requires assembling components with inherent characteristics to produce the overall structure. These systems require certain rules to specify how the components are assembled and have very limited analysis capabilities. CAD systems have been extended to support map design, but their tools for managing and analyzing large geographic databases are limited.
Remote Sensing and GPS
Remote sensing is a science and technology that uses sensors to measure the Earth, such as cameras on aircraft, Global Positioning System (GPS) receivers, or other devices. These sensors collect data in image format and provide specialized functions for utilizing, analyzing, and visualizing these images. Because it lacks robust geographic data management and analysis capabilities, it cannot be called a true GIS.
Database Management Systems
Database management systems specialize in the storage and management of all types of data, including geographic data. DBMS optimizes data storage and retrieval, and many GIS systems rely on it for this purpose. Compared with GIS, they lack analysis and visualization tools.