[Radiance-general] Instances

[Lars O. Grobe]

Hi Lucio,

I have never heard about a case where ambient data became critical 
memory-wise... Why do you think that there is a problem with memory in 
your case? How much memory does the rpict process occupy?

If you have a lot of detail geometry that does not contribute 
significantly to the diffuse-indirect illumination of your scene, you 
can use the ambient exclude parameters of rpict/rtrace (-ae and -aE).

If you use too many instances, or if you create them in a wrong way, 
they will slow down the rendering. Each time a ray hits an instance 
(passes the bounding cube it fits into), it has to check for collisions 
with any surface inside that instance. So if you have a lot of 
overlapping instances with little geometry contained in each, or 
instances with a bad ration of width/length/height, a lot of unnecessary 
intersection checks will happen. Instances improve memory efficiency at 
the cost of rendering time. It is important to balance the two. So only 
pack compact, high-res geometry into instances.

Cheers, Lars.

13.12.2010 10:49, Lucio Boscolo wrote:
> Thank you for all the replies sent through and sorry if didn’t thank yet.
>
> I reckon then that my memory issues were due to the ambient file... I
> always thought it was read from the HD (and this was slowing the process
> so that a balance between calculation time and disk access had to be
> made to optimize the calculation time) but apparently it is loaded
> entirely in memory, which makes sense speed wise and teaches me to
> always simplify my models.
>
> Can you please confirm my understanding is right?
>
> Thank you once again for your great help!
>
> *Lucio Boscolo Mezzopan*

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