Hello!
We have a project with 1100 nadir photos taken by phantom 4 pro. We are trying to georeference the scene with ground control points measured by rtk gps. After alignment and placing gcps we get one component and quite goog residuals also (0.00-0.005). BUT when we take a look a bit closer the sparse cloud there’s clear misalignments. It looks like some parts have reconstucted to two different altitudes but to same x y coordinates. Also there is a few approximately 2 meter height “jumps” in the sparse cloud that should not be there. We used 80% front overlap and 75% side overlap with our images. Any ideas what’s wrong?
Hello Ilari,
do your images contain GPS data? Did you georeference the scene with both GPS coordinates from images and the ground control points? The GPS from images are usually with lower precision than groung control points and if you are using both coordinates for georeferencing there could be a mismatch. You can disable the camera priors before alignment and geo-reference the scene only with using the ground control points or set a higher weight for ground control points’ coordinates.
Also, if it is possible, please post a screenshot of your problem so that we can better understand the problem.
Hi!
Thanks for your reply. We actually tried to align the scene two times, with and without without exif gps and it happens both times. We also did set the camera priors to false.
Screenshot of the first problem:
Hi Ilari,
did you try deleting all components after you added the ground control points and then align again? Sometimes that helps…
Hi,
I’ve experienced such behavior in cases when GCPs placement pattern is not optimal over the project area and the area texture is vegetation or snow mostly. Can you post a screenshot with GCPs in 3D view from the top ? Is your area surface flat without any topography height changes ? Is the texture of this area the same ? It might also be in case of vegetation or some other repetitive texture…