c) Building extraction: A binary ground raster was generated to identify location on the rooftops. Any cells with an elevation greater than or equal to bare earth elevation plus 2.4 were given a value of 1. All other cells were assigned to value 0. To extract building from terrain, DTM was deducted from the DSM which grouped as non-ground surface (Figure 4). Assigning the any value more 2.4m height as a ground mask, the non ground value can be extracted from the terrain.