Autel EVO 2 Pro RTK Vertical Accuracy

[dhill]

We recently picked up the EVO 2 Pro RTK, and I’m seeing some odd vertical datum issues in my data sets. I was trying to compare data sets together and realized that the ground elevations (which are basically fixed heights as it’s a stockpile area) are varying by an uncomfortable amount. I’ve tried modifying the camera settings in Pix4D to correct for rolling shutter, I tried switching to the other autel camera model as it seemed as if the Exif Data has the 10.2 model listed but data online shows that it has the 10.6 model, but each correction attempt seems to yield an even poorer result. As you can see on the check point, the X/Y coordinates are spot on, but the elevation is off by a considerable amount.

Flight settings are:
8 m/s
70/70 overlap
75m elevation from takeoff
Connected via NTRIP

I had assumed perhaps the height in the drone might be off from the RTK component, but upon comparing elevation of the photo and the elevation of my takeoff point, it seems that it is indeed situated 75m above takeoff.

Has anyone else had experience with ONLY the vertical datum being off? I’m currently just using WGS84 ellipsoid for heights to avoid adding in any unnecessary changes imposed by altering the geoid.

[Mike_K]

Hi dhill,
By default, the EGM96 geoid is selected when importing images into Pix4Dmapper. However, we hardcode that the vertical coordinate system for some drones be ellipsoidal heights as they are captured with the RTK method. Often times we have to work with the manufacturer in order to verify the vertical and there can be a delay when it is fully supported in PIX4Dmapper.

Fortunately, PIX4Dmapper version 4.8.2 has been updated and now supports ellipsoidal heights for the Autel Evo II RTK. If you upgrade to this version you should not have any problems with this drone.

Download PIX4Dmapper software

[dhill]

Hi Mike,

Ultimately what I ended up doing to fix the issue was using the advanced settings, putting high trust in the images and going with 10.2 modified for rolling shutter. Now I’m within 4-5cm of my Checkpoints.

Unfortunately I’m noticing that I can’t seem to generate the same results in Pix4DMatic. I’ve applied the HT2 Geoid in Pix4DMatic and compared to my checkpoints and I’m in the ballpark of 1m elevation differences. Does Pix4DMatic have a method to correct for rolling shutter tucked away somewhere?

Thank you!

[Mike_K]

Sounds like you made it work in Mapper. As for Matic, there is no rolling shutter correction available. This may change but for not it is not possible.

[dhill]

Yes, I’ve got Mapper cooperating nicely now. If I wanted to use Pix4DSurvey I’m assuming my optimal workflow would be Mapper then import to Survey correct? (the Automatic Volume Tracing is very handy).

[Mike_K]

Yes, you can open a PIX4Dsurvey project from PIX4Dmapper.