Elevation Models > Special Models (FE / LE)
  On the basis of the different data recording (first and last echo) and the sorting of the elevation values into the raster, a multitude of DSM surface models can be produced. Four basic elevation models are available as standard.
 

DSM FE - highest values


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First echo recording, assignment of high values: small, high objects (branches, high-voltage lines, etc.) are preserved, small gaps between buildings disappear


DSM FE - lowest values


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First echo recording, assignment of low values: small, high objects disappear, gaps between buildings are preserved, buildings become smaller than if high values are assigned
 

DSM LE - highest values


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Last echo recording, assignment of high values: small, high objects disappear, small ditches disappear while small dams are preserved

DSM LE - lowest values


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Last echo recording, assignment of low values: small objects disappear, small ditches are preserved while small dams disappear

Elevation Models > Difference Models
  On the basis of the great number of elevation models, so-called difference models can be produced by subtracting one model from the other. The DSM – FDTM difference model describes the objects on the earth’s surface (building, vegetation and objects not belonging to the terrain) with their relative heights, while the first echo – last echo difference model gives prominence to the raster elements in which two echos were measured (particularly vegetation and edges of buildings).
 

Difference model DSM first echo - DSM last echo


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Difference model DSM - FDTM


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