Automatic registration in more extreme cases

[damonftl]

I'm trying to register a point cloud generated via photogrammetry (many points somewhat randomly placed on surfaces) with a CAD model mesh reference (the opposite of that). I can of course perform an alignment by manually choosing four pairs of points and that works well, but I'm trying to get this done automatically, eventually via command line though that's not important right now. This image shows an example of what I'm working with:



That's after I did an SOR operation on the point cloud and then matched the bounding box centers and scales. As you can see the point cloud needs to be rotated on multiple axes fairly far. ICP does not work in this case - it never gets the alignment even close to correct. I tried the "compute best registration RMS matrix" in the Sand box section under Tools, but that did not work either.

Is there a set of operations that might work in this case? Or am I basically out of luck? Thanks for any help!

[daniel]

Indeed, ICP can only work for roughly aligned clouds.

And sadly there's no magic 'auto registration' tool in CloudCompare...

[damonftl]

Thanks for the quick reply, daniel. Sounds like it's pretty much what I feared. I'll try to find some optimizations on the photogrammetry side, at least aligning the point cloud correctly "up" to start.