Re: bounding boxes for loop's subdivision patches

In Reply to: bounding boxes for loop's subdivision patches posted by Ray on September 13, 2005 at 16:27:02:

: I am working on ray tracing Loop's subdivision surface, and I wonder if there is a fast way to compute the bounding box of each subdivided patch (a patch is a single triangle in the base mesh). Ideally I would like to compute these bounding boxes from the base mesh, NOT the finely subdivided mesh, which is expensive. They don't have to be exact but should be fairly tight for fast ray tracing. Thanks!!

Yes there is. Loop subdivision (as well as many other subdivision schemes) has the convex hull property. That is, the surface lies in the convex hull of its control points. So if you take a triangle from the base surface and consider all triangles that touch that triangle, the convex hull of those control points bounds that patch. You can then compute an axis-aligned or non-axis-aligned bounding box from those control points.

Follow Ups:

• Re: bounding boxes for loop's subdivision patches Ray 13:44:15 09/14/05 (1)
  • Re: bounding boxes for loop's subdivision patches Scott Schaefer 10:18:11 09/15/05 (0)

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