Geographic Information System (GIS)

The emergence of geographic information system (GIS) has solved many location-related problems in people's production and life, and has played a huge role in many fields such as land survey, urban planning, and disaster monitoring. With the popularization of 5G and the rapid development of mobile Internet technology, mobile GIS has also become the focus of the GIS industry. Mobile GIS combines GIS, mobile positioning, mobile database and other related technologies, which can solve problems that are difficult to solve and cannot be overcome by traditional GIS, and open up new application modes for GIS applications, such as navigation in public applications, field data Inspection and other aspects reflect the incomparable advantages of traditional GIS, and bring great convenience to people's production and life. The demand for location-based services is increasing day by day, and mobile GIS continues to provide people with "anytime, anywhere" geographic information services in the development. This chapter will take you into the world of mobile GIS and understand the past and future of mobile GIS.

1.1 Geographic Information System

1.1.1 Overview of GIS

1.1.1.1 Basic concepts of GIS

(1) Geographic information.

Geographical information is a general term for numbers, texts, images, and graphics that represent the quantity, quality, distribution characteristics, interrelationships, and changes of substances related to the geographic circle or the inherent elements of the geographic environment.
Geographical information belongs to spatial information, and the identification of its location is associated with data, which is the most significant sign that distinguishes it from other types of information.
Geographical information is regional, multidimensional, and temporal. Its regionality refers to the identification of the spatial position through the geographic coordinates established by the latitude and longitude network or the kilometer network. Multi-dimensionality is manifested in the realization of multi-thematic three-dimensional structures on the basis of two-dimensional space. In addition, the temporal characteristics of geographic information are very obvious, and geographic information can be divided into ultra-short-term (such as typhoons, earthquakes), short-term (such as river floods, low temperature in autumn), and medium-term (such as land use, crop yield estimation) according to the time scale. , long-term (such as urbanization, soil erosion), ultra-long-term (such as crustal changes, climate change), etc.

(2) Information system.

A system that can collect, store, process data and information, and answer a series of questions from users is called an information system. Information system has four functions of data collection, management, analysis and presentation.
Information systems can be divided into five types: data processing systems, management information systems, decision support systems, expert systems, and virtual offices. Different types of systems have different functions, characteristics, and play different roles. Common information systems include campus information system, library management information system, enterprise management information system, personnel file information system, space information system, etc.

(3) Geographic Information System.

Geographic Information System, the English name is Geographic Information System, referred to as GIS. From different perspectives, for different purposes and different applications, the definition of GIS is different. At present, there is no one that is fully accepted. This book will explain the concept of GIS from the following two aspects.
With the support of computer software and hardware, GIS is a computer system whose main task is to collect, store, manage, retrieve, analyze and describe the location and distribution of spatial objects and related attribute data, as well as answer user questions.

GIS has the ability to process and analyze geospatial data, which is the key to distinguish GIS from other information systems.

In addition, from the perspective of disciplines: GIS is a discipline in the field of recording, processing, analyzing and expressing earth reference data or geospatial data. Borderline, interdisciplinary or comprehensive disciplines based on multiple disciplines such as computer science, geography, surveying and cartography.

A Brief History of GIS Development

The mid-1960s was the initial development stage of GIS. With the development of cartography and computer science, people's demand for planning and management of natural resources and the environment is increasing, which promotes the emergence of GIS. The world's first GIS is the Canadian Geographic Information System (CGIS). During this period, people began to explore GIS ideas and technical methods, and GIS research organizations and institutions continued to emerge.

The 1970s was the consolidation stage of GIS development. During this period, computer software and hardware developed rapidly, and large-capacity storage devices began to be used, which provided favorable conditions for the rapid development of GIS. The demand for GIS began to increase. In a short period of time, many GIS with different themes, different scales and different types were established around the world. At the same time, various GIS software have been successfully developed one after another, and the fields of natural resources and environment have begun to use GIS for data processing.
The 1980s was the promotion and application stage of GIS. Due to the further development of computer technology, GIS has gradually matured, the scope and fields of application are expanding, and it has begun to be applied to some global issues, such as global desertification and global climate change. GIS has a breakthrough progress in this period, at the same time, my country's GIS has also made great progress.
Since the 1990s, GIS has entered the stage of industrialization. With the establishment of geographic information products and the popularization of digital information products all over the world, GIS has become a deterministic industry. At present, GIS has played a huge role in people's production, life, study and work.

1.1.1.3 Components of GIS

GIS is mainly composed of five parts: computer hardware system, computer software system, spatial data, application analysis model, system development management and users.

(1) Computer hardware system.

The computer hardware system consists of three parts: the first part is data processing equipment, which is the main body and core of GIS hardware, such as various computers, servers and graphics workstations; the second part is data input equipment, such as digitizers, scanners, digital Measuring equipment, etc.; the third part is data output equipment, such as plotters, printers, etc.

(2) Computer software system.

The computer software system can be divided into three parts: computer system software, which mainly refers to the computer operating system, is the basic part of the GIS software environment; GIS software, which is the core part of the entire GIS, is used for the operation of various GIS functions, such as Data input and verification, data storage and management, data transformation, data output and presentation, user interface, etc.; database software, GIS needs to support complex spatial data, so data storage, management, retrieval, and output are very important links , the relatively mature database software (such as Oracle, SQL Server, open source database, etc.) has played an important role.

(3) Spatial data.

Spatial data refers to natural, social and human economic data that refer to the spatial position on the earth's surface, which can be graphics, images, text, tables and numbers, etc. It is the operation object of GIS, which comes from various maps, remote sensing images, position observation data, digital ground model, geodetic results, etc. It describes the spatial characteristics, attribute characteristics, and temporal characteristics of geographic entities. Spatial features represent the spatial location of geographic entities and their relationships; attribute features represent the name, type, quantity, and quality of geographic entities; temporal features represent the relative changes of geographic entities over time. Spatial data is generally stored in the computer in the form of a database, which is convenient for users to process and use.

(4) Application analysis model.

Basic GIS tools cannot meet all specific application requirements, so it is necessary to build specialized application analysis models. For example, land use analysis model, flood inundation analysis model, hospital site selection model, cargo delivery route analysis model, soil erosion model, etc. The establishment and selection of GIS application analysis model is an important factor for the successful application of GIS. The application analysis model is the key to the social and economic benefits of GIS technology, and occupies a very important position in GIS.

(5) System development management and users.

With the previous components, it is not enough to form a complete GIS, and people are needed to complete the system design, development, organization, management, maintenance, update, and extract various information and support decision-making.