I’m having some issues with the GCP marking. I have about 2000 images of a road and some bridges. Images are a mix of nadir and oblique photos. GCPs are spread along the road.
When marking 2-3 GCPs and selecting “automatic marking” the GCPs are detected and marked on most images that show the target. The automatically marked images are mainly the nadir ones plus some oblique ones that were shot with a steep camera angle. The position of the green and yellow crosses are typically very good, right in the middle of the GCP.
However, when checking the remaining images, I often notice that not all GCPs were detected and the green cross is some meters off. This is mainly happening on oblique images shot with a flatter camera angle. So I start to add manual GCP tie points on these images, and the green markers start to move towards the GCPs. Perfect!
Unfortunately, at the same time, the position of the green cross on the automatically marked images starts to move away from its previous (very good) position. Not much, maybe 10 - 50 cm.
What is your recommendation how to handle this?