3-D Object Representation
Individual elements are voxels (volume elements)
Compression is almost mandatory
Use octrees (3-D version of quadtree)
- adaptively subdiviside a cube into 8 sub-cubes forming a tree
- stop dividing when the whole cube is entirely full or empty, or the minimum resolution is reached
- at minimum resolution fill the block if majority is full
- combine sibling cubes if they all have the same state
Partially full cubes are nodes, full or empty cubes are leaves
Data space requirement is proportional to the surface area of the object (except a few worst cases)