[Radiance-general] Plotting a large number of simulations

[Greg Ward]

Hi Andy,

Mkillum produces an illum surface that is too close to the BSDF surface for the blinds to be sampled properly as a light source, and at that point everything becomes indirect.  If the BSDF is serving as a proxy for actual blinds geometry, then the illum will be bypassed as well during source sampling.

The only thing that would "sort of" work is to run mkillum in "l+" mode so the window gets replaced by a light source, then use the BSDF as a proxy.  You still wouldn't end up seeing what's outside through the blinds or get striped patterns during solar penetration, but at least the direct and indirect calculations would be reasonable.

I don't see the advantage over a three-phase calculation if you are using BSDFs, which would be a thousand times faster.  The shortcomings are similar, but the costs are very different.

The highest quality results are still going to come from handing the blinds geometry to mkillum and letting it figure out the light distribution on its own.  You can refer to my "first class citizen" talk from the last workshop, where I tried to explain this reasoning.  Unfortunately, I don't know of a good shortcut in the case where you want to look at many blinds positions for the same time step.  Do you have any ideas?

-Greg

> From: Andy McNeil <amcneil at lbl.gov>
> Date: February 27, 2012 5:25:27 PM PST
> 
> On Feb 27, 2012, at 4:43 PM, Greg Ward wrote:
> 
>> If there is some reason you don't want to do this with a 3-phase method, you should include the blinds as part of your mkillum computation, even if that means running it multiple times for different blinds positions.  That way, the interior can "see" the illum source rather than having every source ray blocked by the blinds, which completely defeats the purpose of mkillum.
> 
> Couldn't he put a BSDF surface behind the mkillum?  Then mkillum could sample the BSDF instead of the blind geometry, saving mkillum from having to sample the blinds in all 1000+ simulations.  You could also include blind geometry with direct pass through option for the BSDF allowing the blinds to be seen in the renderings too.  No?
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