Point Cloud/DEM deforms into "bowed" shape after GCPs added; Point Cloud/DEM elevations ten's of meters different than GCP elevations

PIX4Dmapper PIX4Dmapper Questions/Troubleshooting
1

Hello, 

I processed a flight with step 1, initial processing only, at 1/4 image size, so I could add GCPs. The point cloud looked normal, so I imported the GCPs and marked them all using the RayCloud editor, which all went fine as well. I know the elevations of the GCPs are correct as we fly this area very often. Then after re-processing step 1 with the GCPs, the point cloud became very misshapen, and bowed in the middle:

 

I checked all the GCPs and the error in elevation is tens to almost a hundred meters at the edges. Does anyone know what is causing this and how to fix it? Below is the quality report. Thanks! 

2

Hey Grant,

This issue should be related to the measurement of the GCPs or the wrong coordinate system selected while defining the GCP coordinates. In which coordinate system were the GCPs measured?