Contours are generated from digital elevation models (DEM)

DEM’s represent the 3D terrain in point cloud format generated from LiDAR or through a combination of points and break lines collected from aerial imagery

Data density is chosen according to the complexity of the terrain

Planimetric features are surface features which have been extracted in 3D form aerial photography

All visible features such as roads, rooftops, vegetation, rivers, lakes, etc. are traced into a 3D vector file