ISO/TC211 Geographic Information Standard

ISO/TC 211 Geographic Information/Geo-Information Science Professional Committee was established in March 1994. Its purpose is to promote the development, utilization and sharing of global geographic information resources, and to formulate ISO/TC 211 geographic information/geo-information science standard, which is a structured standard for the information of objects or phenomena directly or indirectly related to the location of the Earth. The standard is divided into 25 parts [1]_(as of May 2000), it mainly focuses on the content of geographic information and related methods, the various data management tools and services and related requests, processing, analysis, acquisition, expression, and data conversion in different users, system platforms and locations。

1. Reference Model: This paper describes the use environment, basic principles and standard transformation framework of GIS standard, and defines all concepts and elements of the standard. The reference model is a model independent of any application, method and technology. It is also the working guide of the whole ISO/TC 211 Committee。

2. Overview: Introduction and review of the whole ISO/TC 211 standard series. ISO/TC 211 will be a complete and comprehensive standard family of geographic information systems. This part provides potential users with a comprehensive introduction of standard series and individual standards, including the purpose of standards, standards and the relationships, so that users can quickly query the content , and improve the comprehensibility and acceptability of standards。

3. Conceptual Schema Language: A standardized schema language is used to facilitate the development of interoperability standards and to provide a basis for the rapid establishment of geographic information standards. This standard language is developed on the basis of the existing standard conceptual language。

4. Terminology: All the terms used in ISO/TC 211 standard are defined. The purpose is to generate general terms related to geographic information standards for use by standard makers, users and developers of geographic information systems。

5. Conformance and Testing: To ensure the consistency of all ISO/TC 211 standards, the testing framework, concepts and methods are developed. Establishing standards for testing methods and principles for consistency can enable developers of GIS software to verify the consistency of various standards。

6. Profiles: Definition of all ISO/TC. In ISO/TC 211, a series of geographic information and geographic data management and geographic process standards are defined and described. Among them, there may be several standards in one aspect, such as measurement standards and coding standards. Other standards may describe a series of contents, such as spatial pattern standards. In practical application, it may only adopt a certain standard or part of the standard, or even specialize a standard. Specific standards provide guidance for its use。

7. Spatial Shema: The conceptual pattern of object space features is defined, and conceptual pattern is formulated from the perspective of geometry and topology. Geometry and topology are two main features of geographic information. Their standard-setting will provide convenience for other spatial feature standards, and help GIS developers and users to understand spatial data structure。

8. Temporal Subshema: The concept of spatial entity time scale features is defined, geographic information is not limited to three-dimensional scale, many geographic information systems need time characteristics。

9. Rules for Application Schema: The pattern of geographic information application is defined, including the classification of geographic objects and the principle of the relationship between them and the application pattern. By defining application patterns in a consistent form, data sharing among applications will be enhanced and real-time interaction between applications will be allowed。

10. Feature cataloguing methodology: The methodology of classifying geographical objects, attributes and relationships are defined, and the possibility of establishing an international multilingual classification are determined. Geographic information categories are generally determined by application patterns, providing consistent taxonomy enhances the possibility of mapping from one category to another。

11. Spatial referencing by coordinates: The conceptual model of coordinate space reference system and the guidance of describing geodetic reference system are defined, including some reference systems used internationally. The formulation of coordinate space reference system is also conducive to the communication and data sharing among various applications。

12. Spatial referencing by geographic identifiers: The conceptual model of indirect spatial reference system is defined. ISO believes that more and more geographic information applications use non-coordinate reference systems, namely indirect spatial reference systems, such as address data, so it is necessary to produce a standard model of indirect reference systems。

13. Quality principles: The quality model applied to geographic data is defined. For the creators and users of geographic information, quality information is very important. Consistent quality standard patterns make it easy for data created in one application to be properly evaluated and used in another application。

14. Quality Evaluation Procedures: The guidance of data quality evaluation and description method are given. The evaluation information of geographic data quality needs not only consistent criteria, but also a consistent and standard evaluation and description method. A standard evaluation criterion can ensure that the quality of different data sets is comparable。

15. Metadata: The criteria for descriptive information of geographic information and services are defined. The purpose of this standard is to produce a content of geographic metadata and related standards. These contents include the current situation, accuracy, data content, attribute content, source, coverage area and adaptability to various applications of geographic data. Standard description of geographic data can make it easy for geographic information users to get applicable data。

16. Positioning Service: The standard interface protocol of positioning system is defined. The development of global positioning system makes it possible for a geographic object to locate globally. The formulation of standard interface of positioning information will promote the more effective use of these positioning information in various applications。

17. Portrayal: The portrayal method is defined, and the same symbolic representation method is adopted among different application systems, which will facilitate people to better understand and recognize all kinds of geographic information。

18. Encoding: The coding rules matching the conceptual patterns used in geographic information are selected, and the mapping methods between conceptual pattern languages and coding rules are defined. Coding rules enable geographic information to be encoded in a certain coding language and system when stored and transmitted in digital form。

19. Service: The service interface of geographic information and its relationship with the Open System Environment model are identified and defined. The definition of service interface helps various applications at different levels to access and use geographic information。

20. Functional standards: This paper defines the classification method of functional standards that have been identified in the field of geographic information science. The classification of functional standards is conducive to the harmonization of ISO/TC211 with other standards. The development of standard subsets is also related to the identification of functional standards。

21. Imagery and gridded data: In order to enable ISO/TC211 to process image and raster data in geographic information field model, ISO/TC211 needs to define image and raster data standards. It defines image standards defined by other organizations and other ISO committees, which support the establishment of raster and matrix data standards in geographic information. Because of the increase of image and raster data products in geographic information, it is necessary to establish standards in this area。

22. Qualifications and Certification of Personnel: This paper describes the qualification certification system of personnel in Geo-information science/geo-informatics, and defines the boundary between geo-information science/geo-informatics and other related disciplines and specialties. The technologies in the field of geographic information science/geoinformatics are described in detail. The competence scope and qualification level system of technicians, professionals and managers in this field has been established。

23. Schema for coverage geometry and functions: A standard conceptual model describing the spatial features of coverage is defined. Coverage usually includes raster data, irregular triangulation, point coverage and polygon coverage. In a large number of geographic information applications, coverage is the main data structure, including remote sensing, meteorology, topography, soil, vegetation and so on. Patterns that cover geometry and function will help improve the sharing ability of geographic information in these areas。

24. Imagery and gridded data components: The conceptual criteria for describing and representing image and raster data are given, which include new work for image and raster data: application pattern rules, quality principles, quality evaluation process, spatial reference system, visualization and service, etc. The differences between the new work and the existing standards for vector data are also indicated。

25. Simple feature access - SQL option: This part is a simple element access implementation specification for the SQL environment, which will support the storage, retrieval, query and update operations of elements。

The various parts of ISO TC211 standard depend on each other. The following table describes this dependency. The cell content of “D” indicates that the standard of the corresponding row depends on the standard of the corresponding column, such as “quality assessment process” depends on “quality principle”, “I” means relevant, “X” means irrelevant, “C” means unclear。

Table 17-2: Relations between the top 20 parts of ISO/TC 211