A digital surface model (DSM) is an elevation dataset that records the height of the Earth’s surface including everything standing on it — buildings, tree canopy, bridges and other structures. It represents the first surface a signal from above would strike.
How it differs from a DTM
A digital terrain model (DTM) describes bare earth, with surface objects stripped out. The distinction matters concretely: over a forest, a DSM traces the top of the canopy while a DTM follows the ground beneath it. Over a city, a DSM includes rooftops; a DTM gives the street level under them. Both are types of digital elevation model.
Where DSMs are the right choice
Use a DSM when the objects themselves are the subject: telecoms and line-of-sight planning where buildings block signal, solar potential assessment across rooftops, 3D city modelling, flight-path and drone corridor planning, and shadow or daylight analysis.
How they are captured
LiDAR is the usual source. A laser pulse returns several times as it strikes canopy, structures and then ground; the first return is used to build the DSM and the last return the DTM, which is why both can be derived from a single survey.
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