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DJI Phantom 4 RTK and Pix 4D Georeferencing Error

I recently performed a test flight with the new DJI Phantom 4 RTK, along with the DJI basestation. The flight itself was great, and the images are georeferenced, but the cloud created in Pix 4D is not georeferenced correctly. The X and Y are around 5 feet off, while the Z is closer to 110 feet. Has anyone else experienced this? Is there a specific setting inside of the processing options that needs to be changed to use the corrected RTK data?

Hi,

More on the optimal workflow when processing DJI Phantom 4 RTK datasets can be found in this community post:
[Desktop] Processing DJI Phantom 4 RTK datasets with Pix4D

I would recommend checking the FAQ section in that post for more information. 

Best,

Thanks Blaz. I followed the provided workflow and still experienced a similar error. (see photo, sorry about the photo quality)

This quality report was generated after entering my GCPs as check shots and re optimizing. If I change the check points to gcps and re optimize the average rms error for Z is 0.404ft.

For comparison, I also flew the site with a standard Phantom 4 pro WITHOUT RTK and using GCPs my average rms error for Z is 0.159ft.

I was hoping the P4RTK would have better results if not much better with out without GCPs. Is there a mistake I could have made in initial processing or camera setup?

Thanks

Indeed, the error you get is higher than expected. Especially the Error Z value is high.

Could you provide the following information:

  • The horizontal coordinate system used for GCP measurements.
  • The vertical coordinate system used for GCP measurements, for example, the name of the geoid model. 
  • What was the speed of the drone during the image acquisition?

Please also upload the .p4d file and the quality report here.

Thank you.

The relevant information has been uploaded. 

Thank you for uploading the files.

After processing the dataset I also get the offset in all three directions. 

When it comes to the vertical offset (Z) it is most probably caused by the fact that the GCPs are measured in the respect to Geoid12B that is not directly implemented in Pix4D. More in the FAQ of the [Desktop] Processing DJI Phantom 4 RTK datasets with Pix4D community post.

Do you by any chance have the GCPs also in the WGS84 coordinate system (latitude, longitude)? I would like to check if the same offset appears when using the coordinates that are not yet transformed into a projected coordinate system.