GB/T 40629-2021Specifications for medium scale public map data (English PDF)

1 Scope

This standard specifies the content composition, basic requirements, data organization, overall data requirements, element selection, and selection of medium-scale public map data.

Represents requirements, metadata, etc.

This standard applies to the production, database construction, update and service of medium-scale public map data.

2 Normative references

The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article

Pieces. For undated reference documents, the latest version (including all amendments) is applicable to this document.

GB/T 12341-2008 1.25000 1.50,000 1.100,000 Topographic Map Aerial Photogrammetry Field Specification

GB/T 12343.2 National Basic Scale Map Compilation Specification Part 2.1.250,000 Topographic Map Compilation Specification

GB/T 13923 Classification and codes of basic geographic information elements

GB/T 13989 National Basic Scale Topographic Map Framing and Numbering

GB/T 33183-2016 Basic geographic information 1.50,000 topographic feature data specification

GB/T 35764 Open map content representation requirements

3 Data description

Medium-scale public map data is based on 1.250,000, and the scale is between 1.100000 and 1.1000000

National basic geographic information data that can be used publicly is an important basic and strategic information resource in the construction of national informatization.

The unified positioning foundation and space carrier of geographic elements.

This data includes 9 categories such as positioning basis, water system, residential areas and facilities, transportation, pipelines, borders and administrative districts, landforms, soil vegetation, place names, etc.

The basic geographic information elements are composed of vector datasets and metadata. The vector datasets include the spatial coordinates and attributes of the basic geographic information elements

Information and interrelationships, etc. Metadata is the description of vector data sets. Vector datasets express basic geographic information in the form of points, lines, and polygons

Elements.

a) There are four representation forms for point elements. label point, anchor point, directed point, and place name anchor point. The marked point means that there is no real in a certain range

The expression form of the point element corresponding to the body; the anchor point refers to the expression form of the point element corresponding to the entity; the directed point refers to the directionality

The expression form of the point element; the place name anchor point is the expression form of the place name annotation without the entity corresponding to the point element corresponding to the place name

The center position of the element, line feature, or polygon feature.

b) Line elements are represented in three forms. line, center line, and directed line. Line refers to the line feature or entity contour line (edge) corresponding to no entity

The form of expression; the center line refers to the form of expression of the line element corresponding to the entity; the directed line refers to the line element with directionality or symbolization

The expression form of element is a line collected in a certain direction.

c) There are two representation forms for area elements. contour line facet and range line facet. Contour facets are used to represent faces with well-defined boundaries

Features; range line facets are used to represent polygon features without clear boundaries.