8Maria A Brovelli, Massimiliano Cannata, Ulisse M Longoni. LIDAR Data Fihering and DTM Interpolation Within GRASS [J] . Transactions in GIS 2004, 8(2) : 155-174.
9Kraus K, Pfeifer N. Determination of terrain models in wooded areas with airborne laser scanner data [ J ] . ISPRS Journal of Photogrammetry and Remote Sensing , 1998, 53 (4) : 193-203.
10Lohmann P, Koch A, Schaeffer M. Approaches to the filtering of laser scanner data [ J ] . International Archives of Photogrammetry and Remote Sensing, 2000, 33(Part B3) .
