SJ 20709-1998 Format and encoding of military vector digital map files
Some standard content:
FL0134 Military Standard of the Electronic Industry of the People's Republic of China SJ 20709—1998 Format and encoding of military vectorial map1998-03-18 Release
1998-05-01 Implementation
Approved by the Ministry of Electronics Industry of the People's Republic of China1 Scope
Subject content
Scope of application
Referenced documents
-·General requirements
5 Detailed requirements
Vector digital map file structure·
5.2 Comprehensive map information
5.3 Geographic objects
Appendix A Original map appearance attribute table (supplement)
B Definition of line type, shading type and mark type used for geographical objects [supplement)iiikAoNirKAca
Military standard of the electronics industry of the People's Republic of ChinaFormat and encoding of military vectorial map files1 Scope
1.1 Subject Content
SJ20709--1998
This standard specifies the structure of military digital map files, the map comprehensive information contained, the map original attribute table of the map case and the encoding used in the file! 1.2 Scope of Application
This standard applies to the storage and exchange of vector digital pool maps of 1:10,000 to 1:100,000 military topographic maps and 1:250,000 to 1:1,000,000 coordinated maps used in various applications, and can also be used for other digital map files. 2 Referenced documents
GB1988-89 Information processing, seven-bit coded character set for information exchange GJB 411--87 1:2.5, 1:5 and 1:100,000 military topographic map diagrams GJB417--871:25 Specifications and diagrams for compilation of collaborative maps GJB877-90 Code for information exchange in automated command systems GJB-1839-93 Attribute coding of military digital map elements GJB1840-93 Data requirements for military digital maps GJB220114--93 Storage and transmission of graphic data in automated command systems 3 Definitions
This standard adopts the following definitions.
3.1 Computer Graphics Metafile (CGM) Computer Graphics Metafile (CGM) describes the mechanism by which computers store and transmit picture description information. 3.2 Delimiter Elements Elements that determine the valid structure in a computer graphics file, including the metafile start, metafile end, picture start, picture body start, and picture end elements. 3.3 Metafile Beginmetafile
The Ministry of Electronics Industry of the People's Republic of China Issued on March 18, 1998 Implemented on May 1, 1998
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The first element of a metafile. It delimits the beginning of a metafile description. 3.4 Metafile End end metafile
The last element of a metafile.
3.5 Picture Begin picture
The first element of a picture. It is the starting delimiter of a picture description. 3.6 Picture Body Begin picturebody The element that delimits the end of a picture description and the beginning of a picture body. 3.7 End of picture
Element that delimits the end of a picture.
3.8 Metafile description elements metafiledescrintorelements Metafile companion elements that describe the functional content, format, default conditions, identification and characteristics of a metafile. 3.9 Picture description elements picture descriptor elements A collection of metafile elements used in the interpretation of the entire picture attribute element. 3.10 Control elements controlelements
Metafile elements that determine the address space, clipping boundaries, picture boundaries and metafile index format description. 3.11 Graphical elements graphicalelements Elements that describe the graphics (images) in a metafile. 3.12 Attribute elements attributeelements Elements that describe the appearance of a graphical primitive element. 3.13 Escape elements escapeelements
Describe those metafile elements that are related to the device or system used to construct the picture, but they are non-standardized. 3.14 External elements extermalelements Metafile elements that express information that is not directly related to the generation of the graphics. 3.15 Attributes of map elements featureattributeformapplication Information describing the classification, grading and quality and quantity characteristics of map elements, excluding spatial location information of elements. 3.16 Geometric informationgeometric information Information describing the spatial location and geometric shape of map elements. 3.17 Digital cartographic datadigital cartographic data All digital information describing map elements and their spatial locations and relationships. 3.8 General information for mapGeneral information for mapOverall descriptive and managerial information about a digital map. 3.19 Geographic objectsgeographic objectsComputer description and representation of map elements and corresponding geographic entities. -2-
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3.20 Attribute of primitives bundle indexAttribute of primitives bundle index value in the attribute bundle table, which defines the appearance of the primitive in relation to the workstation. 4 General requirements
4.1 The attribute encoding of geographic objects shall be consistent with GJB1839. The attribute code plus the geographic object number can uniquely mark a geographic object, which constitutes the identification code (ID) of the object. 4.2 The use of CGM binary encoding and character encoding files is for the convenience of use in different occasions. As a file storage, binary encoding should be the main method. 5 Detailed requirements
The format and encoding of the vector digital map file mainly consider the lost digital map stored in the form of a file, and it should also be convenient for the digital map to be transmitted on the Internet. Lost digital map files can also be used as input and output files of the geographic information library. The number and content of parameter codes in each geographic object can be expanded to include more attributes and topological relationships between geographic objects. The number, name, data type, and meaning of parameters corresponding to each geographic object class are not within the scope of this standard. 5.1 Structure of Digital Map Files
Digital map files are based on map feature layers, one file per layer. They are composed of application items that describe map attribute parameters and basic CGM elements that describe graphic data. The specific structure is as follows: CGM element
Metafile start
Metafile description
VDC integer precision
VDC Scope
Map comprehensive information
Picture start
Picture body start
Picture original appearance attributes
Geographic object
Picture end
Metafile end
5.2 Map comprehensive information
CGM element class
Delimitation element
Metafile descriptor element
Control element
Control element
External element
Delimitation element
Delimitation element
Picture original attribute element
External element (geographic object start and attributes) Graphics primitive element
External element (geographic object end)
Delimitation element
Delimitation element
Map comprehensive information is defined by the application data of CGM external elements. The application data format is (type, data). -3-
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Wherein: type is an enumeration parameter used to indicate the type of vector map data comprehensive information, represented by a short integer; data is the data record of the comprehensive information, represented by a string. The definition of the application data of the vector map comprehensive information is shown in Table 1. Table 1 Definition table of map comprehensive information
Application data type
5.3Geographic object
Parameter type
Metafile type, 0: Lost map: 1: Sharp quantity thematic map Coordinate system type, 0: Gaussian rectangular coordinates: 1: Geographic coordinate map Sheet name
Map code
Scale denominator
Standard feature bit; 0: Standard map: I: Non-standard map The lower left of the figure indicates plane rectangular coordinates or geographic coordinates according to the coordinate system type, and the units are km respectively and (°). If it is a rectangular coordinate, the second digit of x is the number
y coordinate of the lower left corner of the map
x coordinate of the upper right corner of the map
y coordinate of the upper right corner of the map
Secret level 0: 1: Internal: 2: Secret: 3: Confidential: 4: Top Secret
Element layer name
Cartographic date YYYYMMDD
Change date YYYYMMDD
Cartographic unit and name
Modification unit and name
Geographic object (also known as entity) is composed of map element code, geometric data and geometric surface attributes. Geometric data and geometric data surface attributes are composed of CGM graphic primitive class elements and graphic attribute class elements respectively. The beginning of a geographic object is represented by application data (1003, data), and the end of a geographic object is represented by application data (1008). Each geographic object has the following structure:
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Application data (1003, data)
Original attribute index
Application data (1008)
5.3.1 Geographic object start
Geographic object start
Geographic object end
The data record data of the geographic object start element consists of two sub-parameters. Sub-parameter 1 is a 16-bit short integer, which is the map feature code. If character encoding is used, its value is represented by GB1988 code and stored in the file. After being interpreted into the memory, it is processed as a 16-bit short integer. Its composition is as follows:
Identification code
The primary code is used to indicate the category of map features. The specific categories represented are as follows: 1: Survey control point category;
3: Independent feature category:
5: Residential land category;
7: : Transportation category:
9: Pipeline and fence category:bzxZ.net
10: Land and political category;
11: Water system category;
13: Landform category;
15: Quality category;
17: Vegetation category;
19~31: Category expansion use,
Identification code is used to identify the real map elements. Due to the different sizes and geometric features of map elements, they may appear as points, lines, and surfaces. The identification code is divided into the following sections; 1~99 is the code for point elements:
100~199 is the code for surface elements:
200~399 is the code for line elements:
400~499 is the general code for point, line, and surface requirements. For detailed definition of identification code, see GJB1839
Sub-parameter 2 is a data structure of indefinite length: it represents comprehensive information of geographic elements and is composed of 5 sub-parameters, defined as follows:
I: geographical object serial number;
SI: number of description codes:
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SI(n): description code (if the previous item is 0, there is no such item):SI: number of parameter codes:
R(n): parameter code (if the previous item is 0, there is no such item)The geographical object serial number represents the serial number of the same type of geographical objects in the map. The primary code, identification code and geographical object serial number uniquely identify the geographical object in this map or in the geographic information database. It can be used as the segment number for retrieving primitives in the map.
Description code is a further quality description of map elements, but it is not used alone. It must be used in conjunction with the identification code to define the meaning of a map element. Its code ranges from 500599 to 600~699 in the user-defined expansion area. For example, to define a TV tower, use the main code 3 (independent feature), identification code 409 (tower) and description code 512 (TV tower), that is, add a note next to the tower. A number greater than 1000 can appear in the position of the description code. If the description code is greater than 1000, it is interpreted as sub-parameter 1, indicating a duplicate code, that is, a map element is registered with another element. For example, when a river overlaps with a county boundary, the main code of the river is 11, the identification code is 43X, the first 5 digits of the description code are 10, and the last 11 digits are 205. The parameter code is a 4-byte real number, which is a further quantitative description of the map element, such as bridge width, water depth, etc. It must also be used in conjunction with the identification code.
For detailed definitions of description codes and parameter codes, see GIB1839. 5.3.2 Geometry appearance attribute index
The appearance of geometric data (such as the line type, line width, and line color of railways) is specified in a bundled manner. Before the metafile is interpreted, the point, line, and surface appearance attribute tables (equivalent to the legend table) need to be loaded first. The identification code determines which table in the point, line, and surface appearance attribute table is referenced, and the original attribute index determines which item in the referenced table. The definition of the geometric appearance attribute table is shown in Appendix A, and the type definition of points, lines, and surfaces is shown in Appendix B. 5.3.3 Geographic object geometric data
5. 3. 3. 1 Point
Points are represented by multi-point marker elements of the CGM metafile, describing elements located by a point. The definition of the location point is shown in 1.1 of GJB411, such as triangulation points, towers, and settlements not represented to scale on the map. 5.3.3.2 Directed Points
Directed points are point symbols that are expressed in the actual direction of the feature and are represented by the directional mark of the generalized drawing primitive in the CGM element. In addition to the central position, an auxiliary point is required to determine its direction. For example, symbols such as bridges, springs, and caves that are not represented according to the scale on the map. 5.3.3.3 Area
Area elements are represented by the filled area primitive in the CGM element. They abstractly represent the characteristics of the surrounding surface defined by their boundaries. For example, lakes, forests, swamps, sandy land, or rivers represented by double lines on the map. The boundaries of area elements-6-
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are composed of line elements and are coded accordingly. 5.3.3.4 Lines
Lines are represented by the polyline primitive in the CGM element. Line elements abstractly represent various terrains characterized by linear distribution, such as railways, roads, rivers represented by single lines, channels, boundaries, contour lines, etc. 5.3.3.5 General points, lines and surfaces
Represented by the above CGM element combination, it is used to represent map elements whose point, line and surface geometric properties change with different scales.
5.3.4 Generalized drawing primitives
Directional signs are represented by generalized drawing primitives, which are defined as follows: Generalized drawing primitives
(integer: GDP identifier)
(point list〉
GDP identifier DMARKE (DMARKE-42) There are 2 points in the point list, the first n points represent the position of the sign, and the last n points only use the x component. Indicates the direction of each sign in degrees.
A1 Point map original table
The point map original table is shown in Table A1.||t t||Chinese layer name
Measurement and control point
Measurement and control point
Measurement and control point
Measurement and control point
Measurement and control point
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature|| tt||Independent features
Independent features
Independent features
Independent features
Independent features
Triangulation points
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Appendix A
Geographic object CGH surface attribute table
(Supplement)
Table A1 Point map original surface attribute table
Chinese entity name
Triangulation points on the ground pile
Military control points
Military control points on the ground pile Point
Leveling point
Independent astronomical point
Smoke and halogen,
Oil, salt, gas wells
Abandoned mines
Oil, gas reservoirs
Gas stations
Substations
Radio masts
Observation stations
Weather stations
Airports
Tower-shaped buildings
Water wheels, windmills, water wheel pumps
Tongqiao fields
Towers, drum towers, passes
Identification codes
15. 14,13
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Chinese layer name
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature
Independent feature
Residential area
Residential area
Residential area
Residential area
Residential area
Residential area
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Continued table A1
Chinese entity name||tt| |Archways, archways, colorful gates
Monuments and other similar things
Old phosphorus forts, old bunkers
Independent stones
Independent graves
Independent houses
Independent manor houses
Small residential areas
Classified houses
Destroyed houses and streets
Yurts, pastoral tents
Peach car turntable
Letting station
Signal machine
Motorcycle shed
Lightship, buoy
Signal pole, signpost
Identification code
Chinese layer name
Residential area
Residential area
Housing land
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Continued Table Al
Chinese Entity Name
Reservoir, water cellar
Reef (open reef)
Reef (hidden)
Reef (dry reef)
Mountain creek, cave
Limestone karst pit
Crater
Small area tree
Broad-leaved sinus tree
Quercus striata protruding tree
Coniferous protruding tree
Independent grove of closed leaves
Palm independent tree version
Coniferous independent tree grove
Sporadic tree technique
Small bamboo forest
Shrubs (small area)
Economic crop forest
Away from grassland
Early land with orientation effect
Identification code
400~421
400~421
405/410
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