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Output coordinate system is not the same warning on merge

I have 13 flights (at least) of a 1,000 acres that I need to merge. I am getting warnings about coordinate system mismatch, but I double checked and they are all identical. The only thing that is slightly different is the geoid separation, but it’s very close, less than a 0.1’ difference across the site. Landing areas differ and I based my geiod heights on the UAV location at each flight. Must all geoid separations be identical or does the cause of the error lie elsewhere? GCPs are not used. All data is based on eBee RTK info and projects created via emotion 3.

Hi Ned,

As you already mentioned, the warning appears because of the different values for Geoid Height Above the Ellipsoid in the project. The software reads the information in the project file (.p4d) of every individual project when performing the merging and when some values are not identical, shows a warning. 

My go-to solution would be to use the same geoid separation value or to transform the height of the images before importing them into Pix4D. This way the Z coordinate will already contain the shift and there will be no need to specify it in the coordinate system dialogs. 

For example:

  • Create a project.
  • Import the images.
  • Export the image geolocation using the “To File…” option. 
  • Open the generated file in text editor in order to change the Z values, e.g. notepad++ or excel.
  • Apply the Geoid Height Above the Ellipsoid to the Z value.
  • Import the updated image geolocation using the “From File…” option.
  • Start processing. 

Let me know how it goes and if the merging was successful in the end.