A DSM is an elevation model which accurately describes the earth's surface including vegetation, buildings and objects.

For each raster element there are several measured values comprising different elevations (ground, gutter, branch, etc.). If the greatest elevation (from first echo) is assigned to the raster element, a surface model is generated describing the visible surface (roofs, tree crowns, lighting pole, etc.).
On the basis of the different data recording options (first and last echo) and the integration of the elevation values into the raster, a multitude of DSM surface models can be generated (special models).

The example here shows two model variants from first echo (FE) and last echo (LE), which are depicted as relief images.