Pix4D Point Cloud from Hyperlapse Images

[ArcTenTen]

I used 125 still images from a Hyperlapse video with a trial version of PIX4D and was able to create this point cloud. It looks like it could be useful with the exception of one thing. The whole point cloud is tilted. The water in the slow moving parts of the river should be flat but isn't.

I also found that the geo-location is off in the flat/ortho view. It's almost as if the point cloud is rotated around an axis and if "un-rotated" it might align with the background satellite image.


The DJI software asked me to re-calibrate the compass at the beginning of the session. Maybe there was enough magnetic interference to shift geo-location??

Maybe my whole workflow was faulty. I don't really know because it was my first attempt at creating a photogrammetry point cloud? Any advice would be welcome.

PS: I'm using a Mavic 2 Zoom flying at 300 ft agl with zoom set at widest angle.

 

[brett8883]

View attachment 109637
I used 125 still images from a Hyperlapse video with a trial version of PIX4D and was able to create this point cloud. It looks like it could be useful with the exception of one thing. The whole point cloud is tilted. The water in the slow moving parts of the river should be flat but isn't.

I also found that the geo-location is off in the flat/ortho view. It's almost as if the point cloud is rotated around an axis and if "un-rotated" it might align with the background satellite image.
View attachment 109638

The DJI software asked me to re-calibrate the compass at the beginning of the session. Maybe there was enough magnetic interference to shift geo-location??

Maybe my whole workflow was faulty. I don't really know because it was my first attempt at creating a photogrammetry point cloud? Any advice would be welcome.

PS: I'm using a Mavic 2 Zoom flying at 300 ft agl with zoom set at widest angle.

Why don’t you just use Pix4DCapture to take the photos and know you are doing it correctly?

 

[Keule]

Maybe my whole workflow was faulty. I don't really know because it was my first attempt at creating a photogrammetry point cloud? Any advice would be welcome.

It looks like the calculated image positions are tilted with respect to the initial camera position and this is why the point cloud generation is tilted.
The issue could happen because of the non-optimal flight plan and I recommend using always a grid pattern mission.

As the M2Z is not supported officially by Pix4Dcapture, use a different app like DJI GSPro or Dronelink.

 

[ArcTenTen]

Why don’t you just use Pix4DCapture to take the photos and know you are doing it correctly?

Mostly because I'm very new to this and decided to try PIX4D after I got home. Also Pix4DCapture doesn't support the Mavic2 Zoom. Maybe I can try some kind of work around.

 

[ArcTenTen]

It looks like the calculated image positions are tilted with respect to the initial camera position and this is why the point cloud generation is tilted.
The issue could happen because of the non-optimal flight plan and I recommend using always a grid pattern mission.

As the M2Z is not supported officially by Pix4Dcapture, use a different app like DJI GSPro or Dronelink.

Thanks for the advice! I'll look into those programs. I flew it as a straight line hyperlapse because I know how to do that. I can see that learning to fly a grid pattern is in my future! (or at least aught to be!)