Introduction to 1:1 million national basic geographical data
National 1:1 million basic geographical data covers the national land area and major islands including Taiwan Island, Hainan Island, Diaoyu Islands, and South China Sea Islands, as well as their adjacent waters, with a total of 77 1:1 million maps. , the overall current situation of this data is 2015. The data adopts the 2000 national geodetic coordinate system, the 1985 national elevation datum, and the latitude and longitude coordinates.
In order to meet the needs of the general public for geographical information data resources, with the consent of the National Bureau of Surveying, Mapping and Geographic Information, some 1:1 million data are provided for free download. The downloaded data are all distributed using 1:1 million standard map format, and the content includes administrative areas (areas), administrative boundary points (territorial sea base points), administrative boundaries (lines), water systems (points, lines, areas), roads and railways (points) , line), residential places (points, surfaces), residential place names (note points), natural place names (note points)** and other 12 types of element layers.
Since what is provided for download is the original vector data, not the final map, there are certain differences in visual expression between it and the symbolized map. Therefore, users who use downloaded geographical information data to compile maps must strictly implement the relevant provisions of the "Map Management Regulations"; if the compiled maps need to be disclosed to the public, they must also perform map review procedures in accordance with the law.
CnOpenData has obtained permission from the National Basic Geographic Information Center to include the 1:1 million national basic geographical database in the public data area for scholars to browse and read. To download data, please go to National Geographic Information Resources Directory Service System.
The content of this page is transferred from the National Geographic Information Resources Directory Service System, the URL is www.webmap.cn .
Result specifications
- Frame number and range
The total number of maps in the 1 million topographic data (2017 version) is 77, and the slicing data is implemented in accordance with GB/T 13989-2012 "National Basic Scale Topographic Map Structuring and Numbering". The spatial storage unit is 6° (longitude difference) × 4° (latitude difference).
- Coordinate system
- Plane coordinate system: 2000 National Geodetic Coordinate System.
- Height benchmark: 1985 National Height Benchmark.
- Map projection: The framed data uses geographical coordinates, and the coordinate unit is degrees.
- Geometry Accuracy
After the update, the plane position and elevation errors of the nearby field control points meet the requirements of the table below, with twice the error as the maximum error.
| Geoobject point error | Minimum | Maximum |
|---|---|---|
| Plane position | 100 | 500 |
| Elevation | 50 | 200 |
- Presence
The currentness of the 1:1 million terrain data is consistent with the currentness of the updated data sources, and the overall currentness of the data reaches 2015.
Outcome data organization
The 1:1 million terrain data currently available for download includes 5 data sets and 12 data layers.
The data hierarchy is named using four characters. The first character represents the data classification, the second and third characters are the abbreviation of the data content, and the fourth character represents the geometry type.
| Element classification | Data tiering | Data tiering | Geometry type | Main elements |
|---|---|---|---|---|
| Water system (H) | Water system (surface) | HYDA | Noodles | Lake, reservoir, double-line river, etc. |
| Water system (H) | Water system (line) | HYDL | Line | Single-line rivers, ditches, river structure lines, etc. |
| Water system (H) | Water system (point) | HYDP | Point | Springs, wells, etc. |
| Residential area and facilities (R) | Residential area (area) | RESA | Noodles | Residence |
| Residential area and facilities (R) | Residential place (point) | RESP | Point | Ordinary houses, yurts, grazing spots, etc. |
| Transportation (L) | Railway | LRRL | Line | Standard gauge railway, narrow gauge railway, etc. |
| Transportation (L) | Highway | LRDL | Line | National roads, provincial roads, county roads, rural roads, other roads, streets, rural roads, etc. |
| Boundary and political area (B) | Administrative realm (face) | BOUA | Noodles | Administrative districts at all levels |
| Boundary and political area (B) | Administrative realm (line) | BOUL | Line | Administrative boundaries at all levels |
| Boundary and political area (B) | Administrative realm (point) | BOUP | Point | Basic Point of Territorial Sea |
| Place names and notes (A) | Residential place name (point) | AGNP | Point | Administrative place names at all levels and names of urban and rural residential areas, etc. |
| Place names and notes (A) | Natural place name (point) | AANP | Point | Transportation element names, memorial and historic site names, mountain names, water system names, marine area names, natural area names, etc. |