9Yue Tianxiang, Du Zhengping, Song Dunjiang, et al. A New Method of Surface Modeling and Its Ap plication to DEM Construction[J]. Geomorphology, 2007,91(1/2), 161-172
10Rossignac J R, Borrel P. Multi--resolution 3D Approximation for Rending Complex Scenes [R]. Technical Report PC17697 IBM Research Division T J. Watson Research Center, Yorktown Heights NY 10958, 1993