P4 RTK questions workflow error in convertin?

[dronesurveyconsultancy]

Hello,

I have a pilot who sends me data collected with the P4RTK, i can only get good results iff i use a lot of GCP's, deselect al the photos and run optimisation on all parameters,  like you would do in a normal P4P workflow.

When using only 1 ground control point i have 8 cm error in Northing axes, can it be that there is a problem with agisoft to convert from WGS84 to my local projection?
In this case i'm using 31370 (Belgium lambert 72).

Thanks in advance

[JMR]

Are you 100% confident that you have set up rtk reference coordinates correctly? You might do a cross check by doing PPK of your dataset and see if embeded geotags are consistent with PPK results.
In my experience Metashape is not always as good as competitors in alignment of projects without any ground control point (direct referencing) . It is sad for me to say so, but I've found it in a few cases.
If you want good results, you need to calibrate your camera in a very well controlled project and then use found lens parameters as precalibrated.
Regards
GEOBIT