I'm working on a project right now that the final goal is to compare two DTMs of a glacier surface from different years to visualize the change over time of the glacial surface. The first DTM was already created and given to me. It was created from data from opentopography (aerial photogrammetry mission flown in 2005). I am tasked with creating the second DTM and was given raw point cloud data in .las format.

This is were I things get tricky. The survey team that took these scans did not use any ground control and no GPS points were taken so the point cloud is floating in space. So far I have tried these methods:

  • Create a .tif in CloudCompare on the Z axis and then create hillshade in ArcMap to try to georeference to a hillshade created from the 2005 data.This is proving difficult because there are no points that are the same in both images because the surface is covered in snow so all the results have a lot of assumptions.

  • Create DEM in ArcMap using LAStools. This produces a DEM at an angle, because the point cloud was collected using terrestrial LiDAR. I can't figure out how to project it on the Z axis.

  • Create a DEM by using the LAS to Multipoint tool in ArcMap, creating a TIN then a DEM. Same thing as above, results at an angle.

If anyone has any suggestions on a route to take that would be immensely helpful. I am running out of ideas. Ultimately I will use both DTMs in Geomorphic Change Detector to visualize the change in the surface between the two years.

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