How can I test if a point lies within a 3d shape with its surface defined by a point cloud?

Question

I have a collection of points which describe the surface of a shape that should be roughly spherical, and I need a method with which to determine if any other given point li

Answer 1

Use a kd-tree.

http://en.wikipedia.org/wiki/Kd-tree

The article provides a good explanation.

I can clear up any further misunderstandings.