ICP challenges

[Craig]

Hi,

I am working on a trail in the woods. I am trying to register the ground extracted from a dense point cloud created via photos in 3DFZ with the ground extracted from a FARO lidar scanner of the same location. The lidar version of the point cloud covers a larger area but both contain an elevated wooden walkway that is 10 m long, and which is the dominant man-made structure in the scene. I have carefully manually aligned the two using the gizmo and I have them so that the structured objects would need to move no more than +/- 1 to 5 cm to get a good alignment.

I then run the ICP registration as per this article How can I register a laser scanned point cloud? : 3DF Zephyr Support. I checked the option to scale the structured objects to match the lidar cloud.

When I do that, it moves the structured objects about 2 m (instead of the needed <5 cm) and gets the registration completely wrong.

1. Is there a way to constrain the registration to have specific limits on translation in each direction and rotation about each axis? If not, can that become a feature request?
2. Are there any suggestions for how to get this to work better today? I'd rather not rely on my manually placement alone, but I cannot get the fine ICP to give any kind of reasonable result.

Thanks, Craig

[cam3d]

Hi Craig - Without seeing your specific data and .ZEP project, it's hard to determine the cause of this mis-alignment. Can you please package up and send us the project and corresponding files so we can troubleshoot for you? Download links can be sent to us privately through support@3dflow.net

Two useful tutorial links:

https://www.3dflow.net/technology/documents/3df-zephyr-tutorials/tutorial-manage-control-points-distances-3df-zephyr/

https://www.3dflow.net/technology/documents/3df-zephyr-tutorials/external-point-cloud-registration/