DEM Database Management System Development And It's Application In Geological Mapping

"Regional Geology Records of China" project started from2008, it requires the Quaternary geomorphology geological map use DEM as base map for the3D display. This article relying on the "Regional Geology Records of China" project, took base on the SRTM DEM (Digital Elevation Model) data, through conducted seamless splicing, projection transformation and other series of operations on the China land area, proposed the China's1:500,000DEM database management system design based on the ComGIS. The system is based on C/S structure, developed with C#+ArcGIS Engine, integrated with ArcGIS, MapGIS, Global Mapper and other professional GIS and graphics software platform, realized the DEM database management system, and made some corresponding functions development on the system. The DEM data management system can be used for any regional data extraction, and then took Hunan Province, Hainan Island and other relative typical regions as the examples for the DEM data extracted from the system and DEM rendering geological map making, it also can provide fast slope, direction, section lines and other geoscience's analysis and so on. Then applied the DEM database management system design ideas and methods to the lunar geological mapping experimental studies, and have achieved good results. The main progress and understanding includes the following several aspects:(1) On the use of several GIS software, filled the black area and solved the inconsistent problem among the DEM data, vector geographic data and geological data from different origin, different ellipsoid, different elevation datum, different projection and ellipsoid parameters. The system could seamless mosaic, rendering, projection transformation and other operations on the DEM raster data, and effective implementation the automatic map matching of the three data.(2) Established the first1:500000grid DEM database management system in the all china land area used for the geological mapping. In the system, the data can not only retrieved by the map frame number, but also by the Administrative Region (province, city, county) and arbitrary polygon area retrieval, it also has the function to convert map projection and scale, can serve earth science research units and social production unit to the greater scope.(3) Combined use of the contour method, the tinting method and shading method mapping techniques, and effective used them in the geological mapping. Mainly uses the DEM hill-shading method for the3D visualization expression and then realized two map show ways by static visualization and interactive dynamic visual, it can display the whole terrain area in the form of a map with two or three-dimensional graphic image style, and also can realize the interactive browse of the terrain data in the database.(4) DEM data management system changes China's geological map spatial database structure and the surface form in the medium and small scale, in addition to the traditional geographic base map in the geological map surface, it can be matched by the DEM image map layer selectively, then overlapped the geological texture and produced the three-dimensional effect. This method turns the2D geological map to3D space, makes the map exhibiting a clear3D geological structure for pressing the actual features of topography, makes the map having stereo and hierarchy perception in ensuring the basis of professional, and enhances the map information, promotes the development of the traditional geological mapping.(5) DEM database and its management system can test the accuracy of boundaries of Quaternary, fault line location and so on when it mach with the corresponding geological graph, if there has any not coordinate between them, we can move the boundary position appropriately in space, so as to improve the position accuracy of the geological map expression.(6) It has strong popularization value, and at the same time the system design and realization method is extended to the lunar DEM database product and lunar DEM geological map produce, also achieved satisfactory results, which confirmed the thinking and the design has good compatibility and expansibility, but also provided some certain reference to other planetary geology map.The national DEM database management system and the application in the typical area achieved good results, it has changed the traditional geological map expression form, improves the accuracy of geological maps. And the system is useful for the rule summary and exploration of the geological mineralization, geological hazard zoning, and land use. Also it has strong promotion and the application value.