About Digital Elevation Model (DEM)
Elevation Models and Digital Elevation Models (DEM) are digital files with the readings of the earth’s surface. There are two types of elevation models: Digital Terrain Models (DTM) and Digital Surface Models (DSM). DTMs are models of the terrain heights (ground level heights). Here are the objects (such as trees and buildings) in the area omitted from the model. This type of model height is often used by utilities and oil companies for laying pipelines and cables on or under the ground or to sheet of wind turbines. DTMs are also required for proper geometric of satellite and aerial imagery. DSMs are models in which just about all objects in the field are included.