How to automatically generate a Digital Terrain Model (DTM)

 
Video: Watch the instructional video related to DTMhere.
 
Important: The DTM is significantly improved when the point cloud classification is used: 115004864586

The Digital Terrain Model (DTM) can be generated:

During processing step 3. DSM, Orthomosaic and Index
After processing step 3. DSM, Orthomosaic and Index

If the point cloud classification is available, a terrain mask is computed based on the classified point groups. Only the Ground and Road Surface groups are preserved in the DTM. To improve the DTM, all the terrain points should be assigned to one of these point groups. To manually move points between the automatically generated point groups, the Edit Densified Point Cloud option can be used: 202560499. If the point cloud classification has not been generated, which is not recommended, all the points are treated as non-terrain points and the DTM is a smoothed version of the DSM. 

During processing step 3. DSM, Orthomosaic and Index

1. On the Menu bar, click Process > Processing Options...
2. Select the processing step 3. DSM, Orthomosaic and Index.
3. Select the tab DSM and Orthomosaic.
4. In the section Raster DSM, make sure that the option GeoTIFF and Merge Tiles are selected.
5. Select the tab Additional Outputs
6. In the section Raster DTM, select the GeoTIFF output file format to generate the DTM.
7. (optional) Select Merge Tiles, to merge the individual tiles and generate the DTM in one file.
8. In the Raster DTM Resolution section, select the resolution of the output file.

 
Note: Due to the smoothing nature of the DTM generation algorithm, results are better when the DTM resolution is moderately lower than the resolution of the project. By default, the resolution of the DTM is set to 5x GSD of the project. It is possible to edit it to a higher multiple of the GSD or any value higher than the default one.

9. Click OK.
10. Process step 3. DSM, Orthomosaic and Index.

After processing step 3. DSM, Orthomosaic and Index

1. On the Menu bar, click Process > Generate DTM.

 
Important: If the Raster DSM is not exported or the tiles of the Raster DSM are not merged, the option is grayed out. In this case, generate the DTM while processing step 3. DSM, Orthomosaic and Index as described above.

 

   
Raster DSM of the center of the city of Lausanne  Raster DTM of the center of the city of Lausanne
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