   Detecting holes in point clouds
  Hello folks,I need an algorithm for detecting "holes" in point cloud, where a hole is more or less defined by an area of a local low in point density. Minimum/maximum radius of such a hole are known. Wanted is usually the biggest available hole. Is there any fast, robust algorithm that can achieve this?Thanks for your kindness.Note: I need hole detection for point clouds, NOT for surfaces!   
  Google might have better knowledge about existing algorithm but the most naiiv approach I can come up with is to pump the point cloud into a scene hierarchy structure such as an octree. Divide the octree until the known maximum radius is reached. Empty leaves are "holes".Of course you would need to further subdivide the leaves to see if the points inside the leaf are evenly distributed. If they are not compare the sub-octree leaves of the leaves with the neighboring leaves to see if holes exist across leave boundaries.   