Phantom 4 Advanced "High Positional Error"

[heliozinhow]

I recently got a P4A to work with photogrammetric surveys. My question is that all the processing I've been doing the positional error presented is WORSE than my P3S error. My question is whether this really is correct considering that the P4A has GPS + GLONASS, better compass and better IMU.

I have already updated firmware, reset in factory mode, caliberi compass, caliberi IMU, caliberi gimbal, everything that could interfere in these results I did and even so everytime I do a flight without GCP the errors are high!

What I need to know:

- Are these ~ error ~ common?
- How can I check if the GPS is ok?

P4A agisoft after Camera Aligment

AND P3S

 

[Bigriver]

Have you tried processing with software other than Agisoft?? Are altitudes and speed of the a/c during image acquisition similar? Lighting? Camera settings? Type of terrain you are mapping, i.e. wooded, urban, agriculture? Have you checked that you are using the proper camera parameters? There are so many variables, but I also would think that the higher resolution of the P4A camera would provide at least as good results.

 

[heliozinhow]

Have you tried processing with software other than Agisoft?? Are altitudes and speed of the a/c during image acquisition similar? Lighting? Camera settings? Type of terrain you are mapping, i.e. wooded, urban, agriculture? Have you checked that you are using the proper camera parameters? There are so many variables, but I also would think that the higher resolution of the P4A camera would provide at least as good results.

Yes, I always process also in the cloud using dronedeploy, pix4d and precisionmapper. In all cases the RMS is high.

Altitudes has little variation. Approximately 0.10m.

The speed of acquisition I always use 10/11 m / s or non-maximum speed.

All these cases are "terrain" with few structures (maximum 1 or 2 houses).

I guess i am using correct parameters. Agisoft identift correctly the camera o P4A (FC6310).

 

[Bigriver]

Do you have the camera set to Mechanical Shutter? What is the altitude of your flights? 10m/s sounds pretty fast, unless you are flying really high. While I haven't tested the upper limits of speed and good images, I am getting good results flying at 14mph at 400'agl, which is around 6 m/s at 120 m.

 

[heliozinhow]

Do you have the camera set to Mechanical Shutter? What is the altitude of your flights? 10m/s sounds pretty fast, unless you are flying really high. While I haven't tested the upper limits of speed and good images, I am getting good results flying at 14mph at 400'agl, which is around 6 m/s at 120 m.

As i remember my last flights i set default my camera settings because sometimes DP or Pix4D use all parameters from DJIGo4. So i dont know if mechanical shutter is a default selection.

The max speed is 15m/s at DP and all my flights are above 400ft.

I am getting good results flying at 14mph at 400'agl, which is around 6 m/s at 120 m.

Without GCP, right? Could u send me a pic after ur aligment and optimization?

Thanks for ur help.

 

[Bigriver]

Setting to mechanical shutter is done in DJIGo4, and should be held when you enter other apps. I'd definitely use the mechanical shutter at the speeds you are flying. I use GCP's. Make sure you are picking up plenty of satellites. Try slowing down and see if the results improve. I use Pix4D for my processing and can send you a quality report, if that is what you are looking for. Not sure if I mentioned it, but I am using a P4P, not a P4A. But there should be no difference in the positional errors.