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DJI FW update 1.07.0060 changes EXIF altitude data (again)

So the latest DJI FW update (1.07.0060) has once again changed how it is populating the EXIF GPS Altitude field.

I believe starting in 1.05 this field was populated with barometric altitude ASL (which was great for photogrammetry). It remained that way through 1.06, but now with 1.07 it has changed back to (the highly inaccurate) GPS derived ASL altitude. 

I believe the sync function is expecting the barometric AGL altitude at present?

Robert,

We flew a site recently that has had some very weird EXIF data outcomes.

Flew at a altitude of 210AGL and once we transfered the data into Pix4D we got elevations of 12meters.

Very frustrating.

Hi Robert and Sam,

The images that are saved on the drone’s SD card are geotagged by DJI.
Regarding the planar coordinates, the drone’s GPS save reliable information in the image EXIF. There is no problem from that side.
However regarding the altitude there might be some inaccuracies depending on the location when you are mapping.

According the latest news on our side that refer to the firmware v.1.7.0.90 and v1.7.0060 for the Inspire I and Phantom 3 Pro respectively, DJI measures the absolute elevation above sea level using EGM 96 as the reference.
They used to only record the elevation above ground level but this is no longer the case.

However the vertical coordinate is still not fully reliable. Indeed, we made testing in our office here and we found that the vertical coordinate is off by several meters that can reach an error of 100 meters. Our users noticed the same.

Therefore our developers suspect something wrong in the DJI EXIF regarding the vertical coordinates.
As a consequence, we always recommend to process with ground control points (GCPs) in order to fix these uncertainties.
About using GCPs: https://support.pix4d.com/hc/en-us/articles/202558699

Note that DJI recently released new versions of the firmware v1.8.1.00 and v1.8.80 for the Inspire I and Phantom 3 Pro respectively.
We do not know so far if they did change something with the vertical coordinate but perhaps they effectively did I fixed the issue.
For more information about the firmware:

We hope this is clear and helps in understanding the situation.

Regards,

hi,i have a project, with a error in the vertical (25m) and have 10 GCPs,  when i include it only fix XY but Z NOT, how i can fix the vertical?

Greetings

hi, any comment about my problem? 

Hi Daniel,

Because of the vertical between images and GCPs, it can be impossible to mark the point using the rayCloud. We would then recommend to follow this procedure: https://support.pix4d.com/hc/en-us/articles/206544136

We would also suggest that you make sure the correct GCP coordinate is selected: https://support.pix4d.com/hc/en-us/articles/202560029
Note that after marking the GCPs, it is required to click Process > Reoptimize to adjust the model to the points.

More general information about the workflows to include GCPs: https://support.pix4d.com/hc/en-us/articles/202560239

Regards,