first of all: I’m really impressed of Pix4D. But in an actual project i have some problems.
First one has something to do with the output of high-values in the point cloud. We have flown with a Phantom 4RTK over an Area of about 315.500 m^2 and have taken nearly 5000 photos in 60 and 80 m above ground (cross).
The inner accuracy was very good. The X an Y coordinates in the point cloud are very good too. But in the Z are errors between 20 and about 50 cm at 11 different Controlpoints. The errors are not constant or homogeneous. Even the GCPs have this height-error (??).
UAV-complete-report.pdf (143.8 KB)
For my own control i have re-calculated one part of the project only with one group of photos (60m). Here are the X and Y very good too. Some Z-values are 1-cm- accurate, some have an offset of 10 cm at the controlpoints. In the point cloud i have seen, that below the surface is another “layer” of points in 2-3 m gap, but not everywhere (photo). What is this?
Can someone help with my issues? Have i done something wrong?
Überprüfung C 3 2 60m_report.pdf (1.5 MB)