I just generated a 3D point cloud / mesh and in Drone2Map and Pro it is beneath the ground elevation and basemap. What is going on here?
This happens when the altitude values from the drone are not accurate and/or ground control was not used. If you are not using ground control, use the Image Altitude tool on the Flight Data tab.
Additionally when you create a 3D point cloud / mesh in D2M, you can also create a DSM and DTM. You can then add one of these (DTM is best) as a ground elevation source in ArcGIS Pro. This will set the elevation in your project area to what was processed in D2M.
I have the same problem with processed outputs being produced below ground, and nothing about the EXIF data suggests that there is a problem with the photo heights.
Photo heights are all ~ 240m. Terrain is flat and an independent DEM for the area covering the drone project area shows an MSL of ~ 130 m. DJI P4 RTK drone flying height was 110 m. Everything adds up.
And yet:2. The DTM is output with values ranging from minus 208 m to minus 191 m3. The DSM is output with values ranging from minus 208 m to minus 138 mThe solution proposed above wont work if the DSM itself is also produced at below ground (which it is).I am fairly convinced this is an issue with the software. The same photo set uploaded to DroneDeploy processes correctly without any modification to the heights, as it should, because they are correct.In Drone2Map I have also experienced other projects with the same negative height issue, flown next to others that are processed correctly. There is apparently no logic to why this happens sometimes.I have lodged a case with a link to download the photos, in the hope that someone can process the project and experience the same issue:
What vertical reference are you using? For the DJI P4 RTK drone we recommend using the vertical reference: Height Above Ellipsoid and leaving the Geoid Height at 0.
Set this for both Image Coordinate System and Project Coordinate System through Options > Coordinate Systems.
Can you give this a try and see if it helps?
If you have already tried this we can get our support team involved to collect more information to help figure this out.
Thanks for the suggestion. However, no change. Previously I had EGM96 set as the vertical reference for both image and project.
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