[Radiance-general] Simulating rooms with blinds: performance

[Randolph M. Fritz]

Greg, I'm confused as to how rtcontrib would apply in my blinds case.  
I think it falls under "arbitrary input-output relationships in optical 
systems," but I am not sure how to do this for my blinds.  Did you do a 
presentation on this?  Something I could read?  Or...?

Randolph

On 2011-01-05 12:50:05 -0800, Greg Ward said:

> Hi Randolph,
> 
> Depending on whether you need to compute the direct component precisely 
> or not, the optimal calculation of a space with venetian blinds is 
> going to come from rtcontrib or mkillum with a BSDF file describing the 
> blinds.  If you use genBSDF to create this file, the geometry is 
> inserted into the final model using mkillum.  If you don't care so much 
> about the direct component (sunlight passing between the slats onto 
> interior surfaces), then rtcontrib will be much faster if you are 
> computing many time points.  My feeling is that this should work well 
> enough for glare evaluations.
> 
> Cheers,
> -Greg
> 
>> From: "Randolph M. Fritz" <RFritz at lbl.gov>
>> Date: January 5, 2011 11:34:22 AM PST
>> 
>> I've been working with a simple model for glare studies, based on an 
>> LBL test room with blinds.  The results are looking pretty good, but as 
>> soon as I put the blinds into the model, single-case simulation times 
>> went up to 2.5-3.5 hours.  Does anyone have any feeling for these 
>> times?  Are they reasonable for a naïve model or too high?  The 
>> processor used is a quad-core AMD Opteron 2376 (2300 MHz) and I've been 
>> using Delaunay's implementation of the Perez sky model, gendaylit, and 
>> calculating five ambient bounces.
>> 
>> Possible lines of attack on the problem:
>> -- Using genBSDF/mkillum (suggested by a colleague.)
>> -- Simplify the blind model; use flat rather than curved slats.
>> -- Review the rtrace parameters I am using.  I'm rereading John 
>> Mardaljevic's chapter in RwR on Daylight Simulation, looking for hints, 
>> but Mardaljevic (are you out there?) was primarily working with 
>> overcast skies, which aren't adequate for glare models, so I'm not sure 
>> how much of his advice still applies.  I'm also going to be sweeping 
>> the archives of this mailing list for ideas.
>> 
>> Anyone have additional suggestions?  Any thoughts on which to try 
>> first?  Are there particular articles it might be helpful to look at?
>> --
>> Randolph M. Fritz • RFritz at lbl.gov


-- 
Randolph M. Fritz • RFritz at lbl.gov
Environmental Energy Technologies Division • Lawrence Berkeley Labs