CloudCompare

This is a 3D point cloud (and triangular mesh) processing software. It has been originally designed to perform comparison between two 3D points clouds (such as the ones obtained with a laser scanner) or between a point cloud and a triangular mesh.

It relies on a specific octree structure that enables great performances in this particular function. It was also meant to deal with huge point clouds (typically more than 10 millions points, and up to 120 millions with 2 GB of memory)