Point Cloud Merge exploded

[AvionAvionics]

Hey guys,

Has anyone had experience merging several point clouds together? I have a large scene from a drone that was scanned and 6 parts that are on the ground. The parts details from the normal flight are not that detailed which we expected so we had the drone do orbits around each part. 3df zephyr didn't seem to like adding all the images at once from the 6 flights and the main flight so we Basically gave each flight its own workspace (1 for the main flight and 1 each for the parts). We then joined each of the parts workspaces into the main scene with control points. The point cloud seemed fine so we kept adding until all were present and then we merged the point clouds. The created mesh looks like a hole was made in the center and ripped into 4 corners and I am not sure why.

Any ideas on what may have gone wrong or is my work flow method wrong or is there a better way? I am using the 3df Zephyr Aerial 3.501

[Roberto]

Hi AvionAvionics,

the workflow is correct. My guess is that the dense point cloud visibility is "wrong" or "corrupted" for some reasons. We have corrected a small issue with dense points cloud visibility happening in v. 3.501/00, but I'm not sure if this is your case (in any case I would suggest to update to the latest 3.503 version)
Anyway, to check if this is a points visibility issue I would suggest you to try the following before generating the mesh:
- right click on the dense point cloud and click 'make unstructured'
- right click on the dense point cloud and click 'make structured'. You can leave the parameters as default. The 'structuring' process will take a while as it will recompute visibility, colors and normals using the cameras information
- generate the mesh

An unstructured point cloud in general can be moved in an independent way in the workspace (useful with laser scan data). When structuring it, the points visibility (along with colors and normals) is recomputed. In this case we don't move the point cloud in any way, but we do an 'unstructure' and 'structure' command just force the recalculation of its visibility. Please let me know if this solve your issue!

[AvionAvionics]

Hi AvionAvionics,

the workflow is correct. My guess is that the dense point cloud visibility is "wrong" or "corrupted" for some reasons. We have corrected a small issue with dense points cloud visibility happening in v. 3.501/00, but I'm not sure if this is your case (in any case I would suggest to update to the latest 3.503 version)
Anyway, to check if this is a points visibility issue I would suggest you to try the following before generating the mesh:
- right click on the dense point cloud and click 'make unstructured'
- right click on the dense point cloud and click 'make structured'. You can leave the parameters as default. The 'structuring' process will take a while as it will recompute visibility, colors and normals using the cameras information
- generate the mesh

An unstructured point cloud in general can be moved in an independent way in the workspace (useful with laser scan data). When structuring it, the points visibility (along with colors and normals) is recomputed. In this case we don't move the point cloud in any way, but we do an 'unstructure' and 'structure' command just force the recalculation of its visibility. Please let me know if this solve your issue!

Thanks Roberto, I takes a little off my mind that my work flow is at least correct. I made the upgrade, made the dense point cloud unstructured and then made it structured. However it fails to structure the point cloud. I tried this 3 times, 1 with default, 1 with several cameras selected, 1 with all the cameras selected. It gives the same error "Structuring failed because too few points are seen by cameras. I am unsure How to proceed from here so I will look through some tutorials and some experiments.

I thought I got 1-2 pieces to merge successfully earlier (or at least I hope I didn't imagine it working correctly) So I may try having the software create mesh after each one is merged just to make sure (I didn't do this before cause it seems to be an inefficient use of time)

[Roberto]

That's really strange and sorry for the issue. If you can send me the zep file (through wetranfer or similar service) tomorrow I will investigate further. I need just the zep project file, not the photos. You can send it to me directly at roberto.toldo@3dflow.net

[AvionAvionics]

Roberto Sorry for taking so long to getting back with you. I am afraid due to the sensitive nature of the content I am not allowed to send anything out. That being said after the Christmas break I did some experimenting and solved the issue. Instead of merging all the workspaces into one scene, I merged the individual pieces together 1 by 1, so eventually had 2 point clouds. 1 Being the main scene and 1 being all the objects. I then combined those 2 point clouds and it produced satisfactory results.

[Roberto]

No worries, I'm glad you solved the issue