From the form of expression, GIS is a computer software and hardware system, and its core is a database system that manages, calculates and analyzes geographic coordinate location information and attribute information of related locations. It expresses spatial location and all information related to location. Therefore, GIS is the representation and synthesis of geospatial entities, and the basic expression form of its information is various two-dimensional or three-dimensional electronic maps. Therefore, GIS can also be simply defined as "a computer information system that collects, simulates, processes, retrieves, analyzes and expresses geospatial data".
(A brief history of the development of geographic information system.
GIS originated from the purpose of "turning maps into digital maps for computer processing and analysis" in 1960s. 1963, Canadian surveyor R.F.Tomlinson first put forward the term GIS, and built the world's first GIS (Canadian Geographic Information System, CGIS) for natural resource management and planning. At that time, GIS focused on geographic processing of spatial data.
Since 1970s, GIS has been consolidated and developed with the improvement of computer software and hardware level and the demand of government departments for analyzing and processing spatial information in natural resource management, planning and environmental protection.
In 1980s, the application field of GIS expanded rapidly, and commercial software began to enter the market. Its application has changed from basic information management and planning to spatial decision support analysis, and the embryonic form of geographic information industry has taken shape.
Since 1990s, with the rapid development of computer technology and network technology, the application of geographic information system has been deepening and extensive, and it has become a regular working system in the fields of land and resources, agriculture, meteorology, environment and urban planning. Especially after 1998 put forward the concept of "digital earth", GIS has developed rapidly in the world and has been widely used in various fields, resulting in huge economic and social benefits.
The development of GIS in China began in the early 1980s, with 1980, the Institute of Remote Sensing Application of Chinese Academy of Sciences, establishing the first GIS laboratory in China, which has gone through preparation (1980 ~ 1985) and development (1985 ~ 1995). Especially in recent years, many excellent GIS softwares have appeared in China.
(B) the latest development of geographic information system
1. is increasingly combined with computer information technology.
In recent years, with the rapid development of computer software and hardware technology and communication technology, GIS technology has also been rapidly developed and widely used, and increasingly integrated with mainstream IT technology, becoming a new direction of information technology development.
On the one hand, the driving force for the development of GIS comes from the growing demand for GIS in an increasingly wide range of application fields; On the other hand, the rapid development of computer science provides advanced tools and means for GIS. Many new technologies in computer field, such as object-oriented technology, three-dimensional technology, image processing and artificial intelligence technology, can be directly applied to GIS. At the same time, due to the rapid development of space technology, especially the development of remote sensing technology, the data of different stages in the earth's space environment are provided, which makes the role of GIS increasingly prominent, and GIS is constantly upgraded, which can provide an environment for storing, processing and analyzing massive geographic data.
With the development of component-based GIS technology, it can be seamlessly integrated with other computer information systems, used across languages, and provides infinitely expanded data visual expression forms.
2. Dynamic, multi-source, multi-dimensional and networked
The latest GIS technology will gradually get rid of the shackles of previous static, two-dimensional and digital map technologies, and develop from traditional static maps and electronic maps to visualization, dynamic analysis and dynamic simulation of spatial information, supporting dynamic, visual and interactive environmental processing, analysis and display of multi-dimensional and multi-source geospatial data. Among them, the visual simulation technology can make people directly interact with the morphological information in the three-dimensional graphic world in real time; Virtual reality technology is mainly based on three-dimensional graphics, combined with network, multimedia, stereo vision and new sensing technology, which can create a virtual digital earth or digital city and make people immersed in it.
The development of advanced earth observation technology, interoperability technology, mass data storage and compression technology, network technology, distributed technology, object-oriented technology, spatial data warehouse, data mining and other technologies has created new means for the development and innovation of GIS.
The fourth generation geographic information system technology
With the improvement of computer hardware performance and the development of mainstream IT technologies such as object-oriented, network and data mining, at present, under the initiative of relevant departments of the Ministry of Science and Technology, domestic academic circles put forward the concept of the fourth generation GIS technology. The fourth generation GIS technology will mainly have the following characteristics:
(1) supports the realization of the concept of "digital earth" or "digital city", develops from two-dimensional to multi-dimensional, and develops from static data processing to dynamic data processing, with time series data processing capability.
(2) Based on the network distributed data management and calculation, WebGIS and B/S architecture, users can call, retrieve, query and analyze remote spatial data, and have the ability of online transaction management (OLTP) and online analysis (OLAP).
(3) Data organization and fusion oriented to spatial entities and their relationships, with multi-source data loading and fusion capabilities such as vector and remote sensing image data interaction, and seamless fusion and interaction of multi-scale data can be realized.
(4) It has the unified ability of massive data storage, query, analysis and processing, data mining based on spatial data and powerful model support.
(5) Have the overall integration ability with other computer information systems. For example, seamless integration with MIS, ERP, OA and other enterprise information systems; Micro-embedded GIS integrates various handheld terminal devices, such as PDA, mobile phone, GPS receiving device and so on.
(6) It has the ability of virtual reality expression and adaptive visualization, and different user interfaces, maps and virtual reality effects appear for different users.
Application of Geographic Information System
80% of the information used by human beings is related to geographical location and spatial distribution, so GIS is widely used. At present, GIS has been applied to military affairs, natural resources management, land and urban management, electric power, telecommunications, oil and gas, urban planning, transportation, environmental monitoring and protection, 1 10 and 120 rapid response systems, etc.
In the future, the application of GIS will be widely used in market analysis, enterprise customer relationship management, banking, insurance, population statistics, real estate development, personal location services and other fields, which will be a new growth point for the development of GIS industry. In fact, the application of GIS will accelerate to all aspects of people's work and life. The popularity of GoogleEarth proves that GIS technology has penetrated into every corner of daily life.
Because of the important role of geographic information in human life and national economy, GIS will maintain the momentum of rapid development in the next few decades and become the core technology in the IT high-tech field.
In recent years, with the development of mobile communication technology, the application scope of GIS has rapidly expanded to people's daily life. The technology of integrating GIS, GPS and GSM has been widely used in vehicle safety prevention system and dispatching system, providing people with anti-robbery, anti-theft, alarm, road guidance, medical rescue and expanding various e-commerce value-added services based on this system platform.
Taking medical rescue as an example, when a patient requests first aid from the monitoring center, the monitoring center can query the specific location of the patient from the GIS electronic map, and at the same time search for the nearest emergency vehicle, so that the nearest vehicle can pick up the patient. After the patient enters the ambulance, the monitoring center can guide the doctors on the ambulance to carry out rescue treatment through the two-way call function, and at the same time, guide the ambulance to the road through the optimal path function of GIS, so that it can reach the hospital or emergency center as quickly as possible. While the ambulance is moving, the patient's family members can immediately inquire about the moving position of the ambulance and the patient's status information online through the Internet. Through GIS, combined with GPS and GSM wireless communication and network, a seamless communication system was established between patients and their families, ambulances and doctors, and finally the patients were treated quickly and timely.
If GPS, GSM or other wireless communication devices are installed on the moving targets of vehicles, fixed targets at home, key protection units and even street lamps, we can get first aid, alarm and various business services through the comprehensive service system composed of GIS, GPS, Internet and wireless communication technologies in urban life, which really makes us live in a three-dimensional and all-round digital life and experience the high-tech value of digital space.
Spatial information technology composed of GIS, RS and GPS will be one of the fastest developing and most exciting fields in the future. IT combines communication and other IT technologies, showing a brand-new way of working and living for human beings (A.R.Mermut, H.Eswaran, 200 1). When cities, countries and even the whole earth are highly concentrated on the computer screen through the latest GIS technology, human beings will have a fuller grasp of their own destiny and future.
(e) Geographic Information System and land management
GIS has long been confined to the field of geographical research and application, and is inextricably linked with all walks of life and our daily life. More importantly, its application field is still expanding, even touching the process of enterprise informatization.
The application of GIS in the research of soil science is a model and simulation realization of the real world. In GIS system, soil resources information can be accessed, transformed and operated in dialogue, which is the basis of soil resources classification, evaluation, planning, management and utilization, and serves the sustainable utilization of soil resources. GIS is applied to all aspects of soil science research, including: ① soil mapping technology and soil sampling technology; ② Prediction and evaluation of soil erosion; ③ Pollution and prevention of soil resources; ④ Evaluation of soil nutrient loss; ⑤ Evaluation and management of soil resources; ⑥ Crop growth simulation, etc. For example, 1983, the United States Soil and Water Conservation Bureau has developed an agricultural land evaluation and land use estimation system, in which agricultural land evaluation includes soil productivity classification, soil suitability evaluation and soil productivity potential evaluation. From 65438 to 0989, the American Soil and Water Conservation Bureau used soil information system to protect soil ecological environment and control soil pollution. 1990 soil erosion prediction model has been successfully applied to soil information system. The main analysis methods are soil erosion nomogram, microcomputer software diagram and river bank erosion nomogram.
1. Establish agricultural production application system.
For example, land resources information system, a Japanese agricultural land, includes soil information system, crop cultivation experiment information system, agrometeorological information system and other subsystems. Bulgaria's computer integrated agricultural management system has been in operation since the early 1980s.
In 1990s, the application of GIS in the field of soil science has been expanding, and its role and status have been paid more and more attention. At the international soil conferences 15, 16 and 17, which started in 1994, the application of soil information system in sustainable agriculture and global change, the structure and networking of soil database and other related issues were continuously discussed. At the same time, the application further tends to the actual agricultural production and directly serves the farm management and operation, such as agricultural technology consultation, pasture water source selection, crop production management, mechanized fertilization and so on.
In the mid-1980s, soil workers in China began to establish soil database and develop and apply soil information system. At the end of 1986, Peking University Remote Sensing Center presided over the research of soil erosion information system, and established the regional soil erosion information system, which was the earliest research of soil information system in China. From 65438 to 0989, Nanjing Soil Research Institute spent two years studying the establishment of soil map and database of soil information system in Sanjiang Plain of Northeast China. In 1990, the soil erosion map of1∶ 50,000 Jiangxi red soil ecological station soil information system was studied. 199 1 In the study of "Drawing up Soil Degradation Map by Using Information System Technology", a series of modern information system technologies, from the establishment of soil land database to the evaluation method of soil degradation, were applied to draw up the evaluation map of soil water erosion and wind erosion in the experimental area; From 65438 to 0992, the mapping of soil and land use information base and information system in Hainan Island was basically completed. 199 1, Shenyang Institute of Applied Ecology, Chinese Academy of Sciences, presided over the research on "Establishment and Application of Regional Microcomputer Soil Information System". The test results in Nong 'an County, Jilin Province show that this is a simple and practical soil information system. From 65438 to 0999, Hu Yueming and others established a red soil classification and evaluation information system using the basic soil database.
2. Predict the spatial change and distribution of soil.
Due to the in-depth application of GIS technology in soil mapping, how to analyze the spatial distribution of soil attributes more accurately from limited single-point original data has become the focus of attention. Specifically, because the information of soil database comes from the synthesis of soil classification, color separation mapping and mapping, the types of soil spatial differentiation have shifted, and modern GIS technology needs a lot of information sources, so many soil scientists focus on the correct expression of soil spatial variability (that is, the correct expression of soil map in GIS).
(1) terrain analysis. Studies by Morre, Bourennane, Gessier and Oden all show that the soil properties in a certain area are obviously related to the topography and landscape position of the area, that is, closely related to the formation process of soil, which can be expressed by the following formula:
Investigation and Evaluation of Cultivated Land Quality Grade in China (Guangdong Volume)
Among them:
Silicon-soil characteristics, such as soil thickness and pH value.
I—— The original topographic data of an area determined by climate, parent material, landform history, vegetation and other factors, such as altitude, slope, concave-convex slope shape, water flow length, specific watershed area, etc., can be calculated by DEM with certain accuracy, and the composite topographic data can be judged by experience or simplified according to the equation describing the physical occurrence process of the underlying surface. GIS technology can generate DEM, so the application of GIS and terrain analysis can improve the accuracy of spatial distribution prediction of soil properties.
(2) The combination of geostatistics and GIS. GIS develops rapidly in storing, querying and displaying geographic data, but it develops slowly in providing spatial analysis module. Due to the lack of universal spatial analysis module, the application of GIS in solving some spatial problems is greatly limited.
Geostatistics was put forward by D.G. Krieger, a South African mining geologist, in 195 1, so this theory was also named after Krieger, and was perfected and founded by Dr. Marcellon, a French geologist, in 1962. This subject has played a great role in the study of mineral reserves. This is a method to find the optimal, linear and unbiased interpolation estimate (blue). After fully considering the geometric characteristics such as the shape and size of the information sample, its spatial distribution position with the block to be estimated and the spatial structure of the grade, the variogram is used as a tool to give a certain weight coefficient to each sample value, and the grade of the block is estimated by weighted average.
Kriging method has been widely used by soil scientists at home and abroad to predict soil properties at non-sampling points. Common methods include ordinary kriging (OK), pan-kriging (UK), indicator kriging (IK), cooperative kriging (CK), regression kriging (RK), point kriging (PK) and block kriging (BK). Their research also shows that when using Kriging method to build a model, comprehensive application of soil and land information, such as soil classification, soil properties in reference area, slope and elevation, can greatly improve the interpolation accuracy of Kriging method, reduce the cost of measuring a large number of samples, and reduce the errors caused by too few sample points. Kriging method has been used to study the spatial variability of soil parameters in China since 1980s, and there have been more and more reports in this field since 2000.
In recent years, some scholars began to study the relationship between geostatistics and GIS, and provided some spatial analysis functions in GIS software. For example, the SAN model of NCGIA in Santa Barbara, USA provides the function of calculating and displaying spatial autocorrelation and other spatial quantities in ArcGIS software. On the one hand, the combination of the two can greatly strengthen the analysis function of GIS, express the spatial information implied in a large number of data and play a greater role; On the other hand, it can also enhance the ability of spatial analysis. With the rapid development of spatial analysis technology and the emergence of new theories, spatial analysis module has become an essential module in GIS.