ICP Registration

[mariobendezu]

Hello Everyone, I was wondering how exactly the ICP algorithm works because I want to align two 3D entities that are from the same place however due to the scanner is not georeferenced (take a relative starting position) , there might be a slight difference between the same points. That is why I would like to know if ICP alignment takes a random closest point or there might be some pattern that would recognize the total 3D entity to match it in the correct way.

[daniel]

Well, it works theoretically if you really had exactly the same cloud (and you use all points at each iteration - see the 'random sampling' parameter).

But in effect, with real life clouds, you have to take into account the density and sampling of the clouds (i.e. real 3D points are not all exactly at the same place) and the partial overlap (you have to properly set the 'overlap' parameter, so as to ignore the points in the aligned cloud that have no equivalent in the reference cloud).