strange calculation of 3d points, several levels

PIX4Dmapper PIX4Dmapper Questions/Troubleshooting
1

Hy, i have made pictures with a gopro hero 5 every 0,5 seconds, the gopro is hanging on a fishing rod at 8 m height and a angle of 45 degrees in front of me and walking about 4 km/hour, a lot of pictures

when i do the first processing step i see several levels of points and some parts having an angle 

the same result when i put GSP in the project, same result

what could be the problem, i have this problem with more projects

Jaap

2

Hello Jaap,

What’s happening here is that you have “almost” two blocks of images. This isn’t uncommon with wide angle cameras such as GoPro’s. What’s happening is that two blocks of images are strongly connected by the automatic tie point matching, but intermediate images are loosely connected to either of these blocks 8with very few ATPs).

The god news is, this is definitely fixable! And you don’t need to do a full recalibration. Here’s how I proceed when this happens to my projects:

  • in the rayCloud, select a point in the ghostly point cloud that seems to be floating in the air
  • note what images it projects into thanks to the right pane
  • select any of them, and mark a manual tie point (MTP) there. Note that this way you will be using the rayCloud MTP editor, which is more convenient than the basic one
  • mark this point in a bunch of images (I tend to use between 5 and 10, using the rayCloud GCP/MTP editor). While doing this, make sure that it’s marked in images belonging to images that project on both subsets of the geometry (the floating one and the good one). If you use between 5 and 10 images it’s very likely already the case. Also, the reprojection of the MTP will be marked in pink (outlier) sometimes, this is to be expected because of the current state of your calibration
  • repeat with a few other MTPs (again, rule of thumb would be around 5 - 10 of them), then reoptimize as hinted by the MTP dialog
  • if this doesn’t solve the issue, repeat with another bunch of 5-10 additional MTPs.

In your case, I would add MTPs on the house that floats higher above the ground, I think that could be enough to do the trick.

Support page related to the MTP editing: https://support.pix4d.com/hc/en-us/articles/202560109-How-to-import-and-mark-GCPs-in-the-rayCloud

Hope this helps, and happy editing!

 

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