3d Terrain Reconstruction Based on Compound Techniques

Digital Elevation Models (DEM) produced by digital photogrammetry workstations supply important information on land form for cartographers and Geographic Information Systems (GIS) developers and users. Since the accuracy of maps, orthophotographs and GIS databases must be within a specified range for appropriate analysis of the information and subsequent decision making, an accurate DEM is needed. Current image matching methods for DEM determination only supply a Digital Surface Model (DSM). This means that matching may not occur on the terrain surface, but on the tops of man-made objects such as houses, or on the top of the vegetation. Hence the assumption, that the elevations comprised within a DEM refer to the terrain surface, is incorrect. A 3D terrain reconstruction method using compound techniques is proposed, which will determine terrain elevations more accurately from overlapping digital aerial images and satellite images. It combines image analysis and image matching methods and hence overcomes errors in the DEM caused by matching on tops of trees or man-made objects.