Orthomosaic Shift

PIX4Dmapper PIX4Dmapper Questions/Troubleshooting
1

Hi, I have a large project, subdivided into sub-projects. One of the issues that I am currently facing is that there is a ± 70 m shift between the image locations and where the orthomosaic/DSM/DTM is located.
The data was captured with a Phantom 4.

Output Orthomosaic:

2020-02-02 (1)_LI
2020-02-02 (1)_LI1920×1080 774 KB

I understand if there is a minimal shift of about 5-10m without using GCP’s, but 70m is a lot.
What can be the cause of this large shift?
Is there any way to rectify this without using GCP’s?
(I can correct the issue by georeferencing it in QGIS, but to do this for 30 sub-projects is not a viable option for me)

2

Image Locations:

2020-02-02
2020-02-021920×1080 695 KB

3

Hi Pieter,

Thanks for sharing the screenshots.
Pix4Dmapper will use the images’ coordinates to geolocate the orthomosaic if there are no GCPs in the project.
What is the background map that you use to compare the coordinates in QGIS?
Could you use some points of reference (for example the corners of your field) instead of a distance and tell us the difference in X,Y, Z that these points of your orthomosaic and the corresponding points on the background map have? It will help us better understand the shift.

Also, what is the images’ coordinate system that you have used to process the project? Please attach the quality report of your project.

You could use some of the QGIS points or Google Maps: Getting 3D GCPs from Google Maps : in order to align the orthomosaic with Google Maps

Looking forward to hearing from you,
Christina