The rendering of my not so fancy scene (100K object, a dozen meshes, one 
light, one infinite object, no photon, no radiosity, few and small glass 
objects,...), I get Bounding box tests = 80% of Light Buffer tests AND a 
very low success ratio of 0.07% !!!!

Are these values typical ?
Is it legitimate to say that  automatic bounding is not very efficient in 
this case ? 80% of all the tests necessary for the redering are made on the 
hierarchy of bounding boxes with a miserable success ratio !
My few tries with manual bounding the CSG (few differences and many unions) 
are not very encouraging. Should I insist ?

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Wasn't it Alain who wrote:
>The rendering of my not so fancy scene (100K object, a dozen meshes, one 
>light, one infinite object, no photon, no radiosity, few and small glass 
>objects,...), I get Bounding box tests = 80% of Light Buffer tests AND a 
>very low success ratio of 0.07% !!!!
>
>Are these values typical ?
>Is it legitimate to say that  automatic bounding is not very efficient in 
>this case ? 80% of all the tests necessary for the redering are made on the 
>hierarchy of bounding boxes with a miserable success ratio !
>My few tries with manual bounding the CSG (few differences and many unions) 
>are not very encouraging. Should I insist ?

Usually, a very low success rate for bounding box tests is very good
news. It means that you've managed to massively reduce the number of ray
tests on your actual object at the expense of a large number of quick
slab tests. If your objects are complicated, ray tests on your objects
might be considerably slower than slab tests. A success rate of 0.07%
suggests that your objects only occupy a tiny area of the image.

-- 
Mike Williams
Gentleman of Leisure

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