[Radiance-general] Simulating rooms with blinds: performance

[John Mardaljevic]

> but Mardaljevic (are you out there?)
I hadn't realised that I'd gone away.
> was primarily working with overcast skies, which aren't adequate for  
> glare models,
Indeed. (Actually, I'd already got a climate-based implementation  
working by then, but the chapter would have ended up longer than the  
book if I'd have tried to include it.)
> so I'm not sure how much of his advice still applies.
Depends on what you mean. The advice re: convergence testing is  
(still) probably applicable to most scenarios, at least for a 'naive'  
calc. But we need to know a little more what your goal is. The bulk of  
the computational effort tends to be, of course, with the prediction  
of the indirect component. So a reasonable estimate for luminance of,  
say, the blinds shouldn't be too onerous since the direct component  
and maybe 1st bounce will usually (but perhaps not always) dominate.  
Same goes for the view to the outside.
> Simplify the blind model; use flat rather than curved slats.
That might not be practicable if it changes the view of potentially  
illuminated slat area.
For what it's worth, I'm still very much with the sceptics re:  
predicting glare for deployed blinds (unless perhaps they're fabric).  
With venetian or vertical blinds, the experienced field of view  
luminance is dependant on the vagaries of user operation, which, I  
feel, renders an evaluation all but meaningless - even for a  
stochastic-based model of user operation (due to uncertainties in the  
parameterisation). I'm open to be convinced otherwise if someone can  
come up with a sufficiently compelling argument.
Cheers
John
-----------------------------------------------
Dr. John Mardaljevic
Reader in Daylight Modelling
Institute of Energy and Sustainable Development
De Montfort University
The Gateway
Leicester
LE1 9BH, UK
+44 (0) 116 257 7972
+44 (0) 116 257 7981 (fax)

jm at dmu.ac.uk
http://www.iesd.dmu.ac.uk/~jm