[Radiance-general] Simulating rooms with blinds: performance

[Greg Ward]

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