GCP checks look good, but selecting points in point cloud at corresponding location has elevations 0.5’ high. I have been using the same process for around 6 years with good results.
Any ideas?
Hello @jlmitchell42, Can you attach the quality report? How did you calculate the offset? For example, did you compare it with the GCPs height? Try to select the point cloud in the area of the GCPs marker and compare with the same GCPs elevation value. There is nothing wrong that i can see in the above table which would explain why it might be happening. If you are using auto marking of the GCPs, I would suggest you to mark them manually.
If the offset is uniform along the project then, there might be issue in properly defining the geoid or ellipsoid height offset on the GCPs vertical coordinate system.
That is what I am doing. Don’t think I can upload due to firewall, but I will try. I usually mark the 3-4 photos then let it auto mark the rest.
MIL AP 20250626_report.pdf (1.5 MB)
Hello @jlmitchell42, I don’t see any issue with the processing. Regarding marking GCPs, don’t auto auto marking, I would say, rather then marking all the images, simply mark 8-12 images per GCPs which is clearly visible. Regarding offset, remark GCPs again as suggested and verify the quality of GCPs coordinate and offset values.