Introduction of Geoinformation and Maps
After many years of development, China has accumulated abundant surveying & mapping geographic information and possessed gravimetric, triangular, leveling and GPS geodetic surveying results, including over 2,500 national GPS geodetic control points 2000, approximately 50,000 national geodetic control points 2000, 20 plus gravimetric datum points, over 120 basic gravimetric points and more than 1,600 national CORS stations. China now owns global 1:1 million vector data, DEM data (1995. 2002), national 1:250k DLG, DEM, DOM data (1998, 2002. 2008), national 1:50k update DLG, DEM and DOM data, 1:500-1:10000 large-scale topographic map data for key areas in all provinces (autonomous regions, municipalities), and vector and image data of wall map for western China (1,027 county) as well as various thematic data, etc. China possesses abundant remote sensing image resources and has accumulated over 5 million aerial photos, covering over 80% of the total land area of China. Multi-resolution satellite images cover over 70 million square kilometers (including repeat coverage); the satellite images with resolution ranging from 10m to 30m cover the entire land area of China; the satellite images with resolution less than 5m have basically covered the key areas; ZY-3 satellite has operated in the orbit for 444 days and archived 325,632 images, including 86,948 orthotropic images, 75,961 forward-looking images, 76,941 rear images and 85,782 multi-spectral images. In 2009, China opened the website of national directory service system of surveying & mapping results (http://data.sbsm.gov.cn), covering directories of state-level and provincial surveying & mapping results, including a total of over 600,000 items of topographic map, 4D product, archives, thematic map and historical map, etc..
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