How to deal with DJI altitude issue during corridor mapping

PIX4Dmapper PIX4Dmapper Questions/Troubleshooting
1

Hello,

I have a problem processing a corridor mapped with a Phantom 4 Pro.

As it’s already known by Pix4D, altitude in DJI drones is faulty and can have swings of 100m. We were aware of that and recorded plenty of GCP to correct it.

The method I usually use is to mark 3 or 4 gcp, then reoptimize the model and mark the rest of the gcps.

The issue I have now, is that it seems Pix4D isn’t able to correct the large difference between the points and the image locations. If I manually lower the points by changing the height of the points coordinate system, the project processes and everything fits. But as soon as I insert the correct GCP locations, the model fails to adapt to the GCPs and I get many uncalibrated cameras and just a very poor reconstruction.

I tried lowering the vertical accuracy of the geotagging to 200m, but it does not help.

What is the recommended workflow with Phantom 4 Pro to deal with this error? Is there no fix to it?

Thank you

2

Hi Jose, 

Have you tried marking a few GCP with the Basic Editor?

Pix4D has support document titled: How to add / import GCPs in the Basic GCP/MTP Editor.

Mark at least 3 GCP in 2 or more images and then after Step 1, you can mark the remainder of the GCP via the rayCloud.