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Problem with Ground Control Points

Hi everyone.
I have a project with 5 GCP, wich position is correct in axes x and y, but in z there is an offset in the option “Calculated Position” in Pix4D. What could be the problem?. Thanks a lot.


Can you please send us the quality report in pdf format?


Ok, here it is.

Quality report.pdf (2.1 MB)

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Welcome to the Pix4D Community!

Do you know which vertical coordinate system was used to retrieve the coordinates of your checkpoints? Can you please confirm or reject that EGM96 Geoid was used?

What results are you getting if you set some of your tie points as 3D GCP and leave the other as checkpoints?


I have done tests with the EGM96 and EGM2008 geoid, and I have the same problem.
The 5 points are control points, so I am going to put some points as 3D GCP and others as checkpoints.

@karinamar.banos, since you are not using a drone with RTK/PPK geotags, it would be recommended to use some GCPs to georeference the project.

In general, we recommend 5-10 GCPs per project. So you should consider measuring additional points next time to be able to use them as checkpoints.