Brief introduction to geographic information system standards

With the development of GIS technology, especially the application of network technology in the construction of GIS, standardization related to it has become a problem that must be solved. A good standard is an indispensable part of promoting, guiding and ensuring efficient and high-quality geographic information exchange。

In the field of information technology, standards and norms can be divided into two kinds according to their usage status, actual standards and standards in legal sense. The former is a widely accepted standard, such as TCP/IP protocol and OpenGIS specification, developed by relevant institutions, groups and organizations in the process of continuous practice. The latter is usually formulated by law for the purpose of policy or management, such as the content standard of spatial metadata formulated by FGDC。

According to the size of the jurisdiction area, standardization organizations for information technology can be divided into five levels: international standardization organizations, such as ISO; regional standardization organizations; national standardization organizations, such as ANSI and the Federal Geographic Data Commission of the United States; government and user standardization organizations, in the field of GIS, OGC (OpenGIS) belongs to this level; and complementary standardization organizations。

At present, in China, GIS-related standards in GB series are mainly geocoding standards, including GB2260-80, Code of Administrative Division of the People’s Republic of China；GB/T13923-92, Code of Classification and Code of Basic Land Information Data; GB14804-93, Classification and Code of Topographic Map Elements at 1:500, 1:1000, 1:2000; GB/T5660-1995, 1:5000, 1:10000, 1:25000, 1:1000. 00 Topographic Map Element Classification and Code, etc.。

Generally, the standards and norms of information technology can be divided into the following five aspects：

1. Standards for Hardware Equipment. In network technology, there are a large number of such standards, such as the IEEE 802 series；

2. Software standards. Including operating system, query language, programming language, graphical user interface and so on, such as SQL, DCOM, CORBA, etc；

3. Standards of data and format. It includes data model, database construction, data quality and reliability, classification system of geographical elements, data format conversion, etc. In the application of geographic information, spatial data coding standards, metadata standards and so on belong to this category；

4. Data set standards. Data storage file format standards, such as the U.S. Census Bureau’s TIGER file standards；

5. Process Standards. For example, ISO9000 series and CMM are mainly for the guidance of system development process。

Geographic information system standardization mainly includes the following four aspects: software tools, such as documents, design, acceptance, evaluation standards and software interface specifications; data, including data model, data quality, data products, data exchange, data display, spatial coordinate projection; system development, system design process, data process, benchmarking, etc. The process of quasi-construction of the database; other, including terminology, management methods, etc. Generally speaking, the standards of software tools, system development, management methods and so on can borrow more general information technology standard specifications, so GIS standards mainly focus on spatial data and a series of related specifications。

The application of Geographic Information System (GIS) standards can establish a more standardized data input and processing, the aim is to improve work efficiency and quality, and use consistent data format and spatial data visualization to guide the use of data。

In a word, introducing a series of standards into geographic information system is conducive to ensuring the standardized development of geographic information system technology and its application, guiding relevant practice activities of geographic information system, expanding the application fields of geographic information system, and thus realizing the social and economic value of geographic information system. Based on the geographic information system standard, the sharing and interoperability of geographic information in different application areas can be realized, which is one of the key technologies to realize the digital earth (Figure 17-1)。

Figure 17-1: Significance of geographic information standards for geographic information system applications

Standard formulation process of ISO: [Cargill]

The formulation process of ISO standards is mainly divided into the following steps：

1. Because of the subcommittees draft new work content plans, it needs to submit them to a technical committee for a vote；

2. After the voting is passed, the subcommittees shall be responsible for the activities related to standard-setting；

3. The working group under the subcommittees drafts the draft standard work and submits it to the subcommittees for voting；

4. If the subcommittee unifies the draft standard work, the draft will become the draft standard plan and be circulated throughout the technical committee；

5. If the technical committee can also reach a consensus on the draft plan, the draft standard will be sent to the head of the technical committee as a draft international standard；

6. The head of the technical committee will verify the draft international standards and check whether they conform to the principles and requirements of ISO；

7. If approved, the draft international standards will be circulated among ISO members for comments and votes. If approved by 75% of the members, it will be submitted to the Executive Committee of ISO for publication and distribution as ISO standards。

At present, many organizations and government departments have convened or presided over the formulation of geographic information system standards, which mainly include spatial data model and spatial service model, as well as Data Sharing and Data Interoperability. Among them, the ISO/TC211 geographic information standard formulated by the Geographic Information/Geomatics Professional Committee and Open GIS formulated by OGC (Open GIS Consortium) are the main ones。

Compared with OpenGIS, ISO/TC211 is more comprehensive and focuses on the definition of standard itself, which can guide all aspects of the development and use of geographic information system. OpenGIS pays more attention to the realization of software because of the participation of many well-known GIS software developers。

Interoperability of geographic data:

With the development of geographic information system, geographic data sharing is needed, and interoperability is the inevitable outcome of data sharing。

In traditional GIS applications featuring centralized data management, data sharing is mainly achieved through data exchange, including direct conversion through related tables or converters and indirect conversion based on spatial data conversion standards。

Spatial data interoperability aims at heterogeneous databases and platforms to realize data processing interoperability. Compared with data conversion, it is a “dynamic” data sharing, independent of the platform, highly abstract, and it is the development direction of spatial data sharing。

There are many levels of spatial data interoperability, ranging from hardware-oriented interoperability at the lowest level to semantic sharing among information groups at the application level. The following table gives the level of interoperability and its support。

Table 17-1: Geographic data interoperability and its support (Chen Shupeng)