Global Mapper v25.0

Bad building representation at DTM

schsan
schsan
in Raster Data

Hello,


In terrain with a lot of vegetation, the creation of a DTM works well. But as soon as buildings are present, I always get a structure that just doesn't fit. The structure clearly reflects the heights of the building roof. The Lidar points were all classified as buildings and do not have a single ground point. How can I create a visually fitting DTM from this? I want a DTM, based on the ground points around the building, with no structure. Quite simply a straight surface. Even tutorials on Youtube or the documentation of the Global Mapper course I took do not address this. It is never shown how to create a terrain in an area with many buildings. Is this a known problem that does not currently work better? Or is there a tutorial I did not find?

Greetings schsan




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Answers

  • Michele
    Michele

    Hello,

    Just for info but this happens also when using terrain painting tools if you first set parts to no data and then try and fill holes.

    I don't think it's related to the existing data but more about how it fills the empty spaces.

    Best regards

  • BMG_Amanda
    BMG_Amanda

    It's interpolating from the closest ground points to fill the hole in the data. To create smooth surfaces instead, you can use polygons as 3D breaklines (similar to the lake in the watershed workflow from training). A quick way to create polygons is to use the Lidar Feature Extraction tool to create footprints. These footprints will have the elevation data needed to be used as breaklines in the Create Elevation Grid tool.

    https://www.bluemarblegeo.com/knowledgebase/global-mapper-24/Lidar_Module/Lidar_feature_extraction.htm

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