Hi All,
I'm using MS Pro v2.1.3.
I have carried out a UAV flight with a DJI M300 and P1 camera of a pedestrian foot bridge. I have flown nadir and oblique flights and also captured images with a Canon hand held camera. Prior to the flight we placed many black and white targets on the bridge.
After aligning the images using highest accuracy setting and then running the detect targets command, Metashape has picked the centre of many targets correctly. Metashape allocated Marker numbers for those targets. I have noticed that Marker No 6 has been correctly identified (center of target correctly picked) in 36 images. I also notice that Marker No 14 has been correctly identified in 13 images. The problem is the target is the same target! Marker 7 and Marker 11 are about 15cm apart.
The images Metashape has picked the centre for Marker 6 are different to the images Metashape has picked the centre of Marker 14. So for Marker 6, the marker is centered on the target in its images. And the Marker 14, the marker is centered on the target in its images. How can this be?
In the Reference Tab Markers list the difference is shown "View Estimated" Table -
point 14 355681.7410382535 6308320.882072767 3.6456287776534353 13
point 6 355681.8124383928 6308320.808663793 3.7618934840380938 36
Does this mean the photos have not aligned correctly and Metashape thinks there a two targets in that area even though there is only one target there? The detect marker settings were "Tolerance" = 1 and " Maximum Residual (pix)" = 5.
Does this also mean there is Tie Point Discrepancy in the sparse cloud in that area? If that is the case, I would have never have found this if I didn't have a target there. How could I have identify this issue with no target? It would also suggest there could be issues in other areas but I would not know until I have created a model or point cloud and could see the issue.
Please see attachment showing the issue
Any help appreciated
Kind Regards
Ben