High Resolution 1:10,000 scale Mapping Strategy of Multi ... - NDMA

smooth motion of the satellite in orbit, the changes are small and can be modeled by
low-order polynomial functions.
4. Digital Terrain Model (DTM) and Digital Surface Model (DSM)
A digital terrain model (DTM) is a 3D digital representation of the Earth's
terrain or topography. Automatic DTM extraction involves the automatic extraction of
elevation information from imagery and the subsequent creation of a 3D digital
representation of the Earth's surface. A DTM represents the elevation associated
with the Earth's topography and not necessarily the human-made (e.g., buildings) or
natural (e.g., trees) features located on the Earth’s surface.
A digital surface model (DSM) represents the elevation associated with the
Earth's surface including topography and all natural or human-made features located
on the Earth’s surface. The primary difference between a DSM and a DTM is that the
DTM represents the Earth’s terrain whereas a DSM represents the Earth's surface.
Figure below illustrates a DSM.
DIGITAL SURFACE MODEL OF AN AREA DTM OF SAME AREA
Figure App 20.8: DSM Modelling
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