Topographic mapping

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