Wasn't it Christoph Hormann who wrote:
>
>Because I needed some simple rectangle shape for a scene I am working on
>and because it is used about 1000 times in the scene, I tried some
>different possibilities building that shape and checked
>memory-use/tracing time.  
>
>It is just a very quick test on a concrete scene, differences in time
>are quite low, so you probably can not say anything definitive from
>these values (did not want to wait longer :-).  BTW, scene also contains
>many other objects.  
>
>Any comments/ideas ?

I'd guess that the vast majority of the tracing time would be consumed
by looking for the bounding boxes which have been automatically
generated. Each ray has to be checked against all 1000 bounding boxes,
but once the bounding boxes have been located, the ray only has to be
checked against at most one actual object. (Because the object exactly
fills the bounding box, if there's no reflection or transparency the ray
will always terminate at the first object). So the construction details
of your object would only be expected to have a tiny influence the trace
time.

-- 
Mike Williams
Gentleman of Leisure

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