[Radiance-general] Instances

[Jack de Valpine]

Hi Lucio,

When a Radiance job is running (rpict, rtrace, rvu, etc) the whole scene 
(octree) is indeed in memory. It is not being loaded from disk as 
needed. Depending on how your model is made and with what level of 
detail this can get very big. Where possible and convenient in makes 
sense to try to put your scenes together in a thoughtful manner. On the 
other hand scene complexity/size does not necessarily mean longer 
simulation times (eg, complex exterior scene under sun/sky only lighting).

-Jack

-- 
# Jack de Valpine
# president
#
# visarc incorporated
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# channeling technology for superior design and construction


On 12/13/2010 5:40 AM, Lars O. Grobe wrote:
> 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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