CloudCompare forum

Hi everybody,
I'm working with CC (version 2.6.1, windows 64bits) to align:
- a high density point cloud (which corresponds to a panel with particular shapes scanned with laser)
- on another one containing the absolute position of some of its reference points.

For that, I use the "Align two point clouds by picking equivalent points pairs". I manually make the both point clouds roughly overlap for better visualization and point selection, and select the corresponding pairs.

My problem is here:
- When I select only 3 pairs (which is not enough), I obtain a coherent result, with RMS around 0.01m, which is what I expect.
- When I select 4 or more pairs, my panel makes a 180° turn, so the pair points are not coherent any more, and my RMS is around 1m (my panel dimensions are 1.5x1.5m)

Did it already happen for some of you, and is there a particular manipulation that I can do to force the alignment to be coherent ?
I have some screenshots if needed, I just don't know how to upload them...
Thank you very much in advance for your help !

Camille

Indeed, I believe this is the same issue as this one:
https://github.com/cloudcompare/trunk/issues/236

Are your points all aligned on a plane?

Yes, it looks like it's the same problem !
And no, my points are not always on the same plane. It's a scan from plane structure, but with blocks added on it, and holes. I measured the position of the edges which were in the holes, on the main surface, and on the edges of the blocks. All the points needed are between two planes spaced from about 15cm.

Okay I've fixed the bug. Hopefully it should now work properly.

You can download the latest 2.6.3.beta version from the website (Windows 64 bits only for now).

Hi,
I downloaded the last version you updated, and it looks like it's working ! I tested it with the four points from the example here : https://github.com/cloudcompare/trunk/issues/236 and with my own data. It seems to be ok.
Thank you very much for your help and for the quick answers ! It's really nice to have access to such a tool with a good support :)