[vtkusers] Is it possible to have a "bounding sphere" for an actor

[David E DeMarle]

Using bounding boxes is sufficient to compute intersection tests, but
depending on the data sets geometry, an acceleration structure based
on spheres may be more or less efficient. If you use bbox min and max
points (extreme corners) to calculate your center and radius, you will
create a sphere that contains the entire bounding box and additional
empty space.

Which primitive is better in practice is a function of how long it
takes to create the bounding primitive (sphere or box), how long it
takes to test for intersection against the primitive, and how much
empty space (source of false positive tests) is contained by the
primitive.

Good luck. I'm looking forward to seeing what you come up with,
Dave DeMarle

On Sat, Nov 8, 2008 at 4:28 AM, Elvis Dowson <elvis.dowson at mac.com> wrote:
> Hmmm,
>                I don't think I'm on the right track here. A sphere can be
> fully contained inside a square box, so it will be sufficient to just use
> the bounding box, to compute intersection tests.
>
> Best regards,
>
> Elvis Dowson
>
>
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-- 
David E DeMarle
Kitware, Inc.
R&D Engineer
28 Corporate Drive
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Phone: 518-371-3971 x109