CloudCompare forum

Hello,
I am analysing a landslide which shows movement in -z, -y and -x direction between 2 point clouds.

Now I have a question regarding the M3C2 settings:
When I'm choosing my preferred orientation in the "Normals" section, e.g. "-Z" how will the normals change?
How does it calculate the M3C2-distance?
What is weighted and how?
Is the result of the displacement only along -Z and not +Z, X, Y, etc. or does it include all directions?
If it is only along -Z, should I do the calculation in all directions to get all the X-Y-Z components?

Thanks in advance!

When you compute normals on a point cloud, we fit a plane to the local set of points (a point and its neighbors) but there are 2 ways to orient this plane (one side or the other). By specifying '-Z' you tell CC to prefer the normals point towards -Z (if that makes sense). So it's important to give a good orientation heuristic if you want your normals to be all (or as much as possible) properly oriented.

You can compute the normals before launching M3C2 (with Edit > Normals > Compute) to get more control and be able to 'see' the result.

Then, M3C2 will compute the distances by looking for the matching points in the other cloud inside cylinders. Cylinders are oriented thanks to this normal.

For more detailed information, you'll probably have to read the article (see the link on the wki page: https://www.cloudcompare.org/doc/wiki/i ... 2_(plugin)).