CloudCompare forum

Hi,

I am confused about how to properly define my parameters for the Kd-tree fusion specifically the maximum relative distance and all the parameters for the facets ( max distance @ 99%, min point per facet and max edge length). Is there some standard procedure to define these values? I can't seem to find anything to go off of.

I am most confused about the Max edge length parameter. Is it better to keep it large to allow bigger facets? I read that this can result in elongated triangles. I'm really not sure what numbers to use.

Sadly, these parameters are not easy to set automatically as it depends a lot on your cloud (density / level of noise / the expected 'roughness', etc.)

For the max edge length, it's actually easier. It's just used to extract the (concave) contour at the end of the facet extraction process. So it doesn't depend on the other parameters. The larger the parameter is, the cruder/simpler the contour will be (in the worst case it will be the convex hull). The smaller it is, the closer the contour will be to the points / facet boundary. But of course, if you set it too small, it will take more time, and the contour might actually be super noisy as it will stick to much to the points.

Hi daniel,

Thank you for responding. Can you explain to me what the max relative distance is. I'm aware that it's the 'maximum distance between the merged patches and the current facet center'. However, when I make it small such as (0.5) my cloud is divided into rather small facets even if the surface is rather smooth. I am confused by this definition, could you elaborate? I am also wondering if this distance in meters?