CloudCompare forum

As far as I know, there is no free software that can do this today. It would also be neat to be able to classify "ground" "buildings" etc, but model keypoints is the most important one.
In my workflow, model keypoints are the points that are used to triangulate a cloud, and today I have to use Terrascan to do it. It only has 3 settings, "use point every" for setting density in flat areas , and "Tolerance above" and "tolerance below".
If this could be included in CC, a lot of people would be really happy :)

Sorry, what are "model keypoints" exactly? Are they real objects?

Model keypoints are the points that are needed to represent the cloud as close as possible without losing detail.. It's class 8 in las i believe. Usually you run model keypoints on ground points before triangulation, as triangulating all ground points would create a mesh that is way to heavy. So instead of simplifying the cloud based on distanse or similar, it will keep points on edges etc. Look at the model keypoint function in terrascan too see how it works. Laztools has the functionality as well in one of the tools.. You set the max min value for how much z variance it will take before keeping a point, and also what the distanse in a flat area it should allow before adding a point. So typically for airborne lidar, you set 0,15 +- for z and a few hundred meters for the flat areas. That way you get a mesh that is pretty close to the ground points without losing much detail, and you reduce the resolution with an insane amount. And there are really few tools that does this. So this would be a game changer for CC :)

"lasthin" from Lastools also does this:

For adaptive thinning use '-adaptive 0.2 5.0' where 0.2 specifies
the vertical tolerance that a TIN through the thinned points is
allowed to deviate from the complete set of points and 5.0 the
maximum distance between points. The default for the latter is
10.0 if you only specify '-adaptive 0.15'.