Abstract: It is still a current technology problem to build a fine DEM in urban using single technology because of dense buildings,vegetation,heavy traffic,etc. This paper discusses a method to build a fine DEM based on large-scale digital topographic map,DOM and DEM generated by UAV photogrammetry or laser radar point cloud data (DSM). Firstly,contour and elevation points are extracted from large-scale digital topographic map,which can be directly used to construct DEM. Then some extraction is separately done to get terrain-related line elements,which are always 2D without elevation information,such as contour of buildings,road sidelines,square boundaries,scarps,lake sidelines and so on. Then some necessary process is done to build 3D-lines after obtaining from the correct elevation of general DEM and DSM. Based on these 3D lines and elevation points,a heterogeneous TIN model is constructed using constrained TIN methodology. Because of data source with different accuracy in different area,the modeling accuracy is also analyzed using theory and practice. Experiments show that the constructed DEM is so high consistency with the topographic map that can better meet the needs of flood analysis,urban fine management,and real three-dimensional construction.

Key words: fine DEM, multi-source data, modeling method, urban DEM