Volumetric Clipping Algorithm


The Volumetric Clipping Algorithm is applied to the rig primitive during extraction of geometric and recognition information. The main goals of this operation are:




The clipping algorithm is based on the intersection of convex shapes: an object is identified byits bounding box and the view volume is represented by a frustum. It is then possible to define a particular algorithm based on increasing complexity, starting from low complexity cases which occur frequently to those of high complexity and which occur with low frequency.

The test is performed by searching the intersection between the edges of the bounding box and the view volume. Hence, the two main operations are:

  • search a vertex that falls inside a convex region;
  • search an edge that intersects a plane of a convex region.

The clipping algorithm is based on the following operations, performed in sequence according to an order of increasing complexity:

1. at least one point of the bounding box falls inside the view volume;

2. at least an edge of the boundin -box intersects the view volume;

3. at least one point of the view volume falls inside the bounding-box;

4. at least an edge of the view volume intersects the bounding box.

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