Abstract: A view-dependent and real-time LOD algorithm is presented,based on the algorithm of surface units in high accuracy surface model(HASM).The grid data in DEM is divided into patches and organized in surface units.In the process of reconstruction of the virtual terrain for DEM,the surface units are interpolated at intervals in proportional to the distance between the units and the view point so that the LOD in the field of vision is produced in real time.The dynamic DEM data delamination and the scene of 3D virtual terrain are implemented by the method to reduce the consumption of system memory without building the hierarchical model for the regular grid DEM data.