[Radiance-general] Radiance-general Digest, Vol 166, Issue 13

[Greg Ward]

Hi Marouane,

Looking at your original post again, I would say that relying on rtrace and the default calculation to determine the tiny bit of light that bounces many times between closely-spaced diffuse surfaces and makes it into your room is the problem.  This is very close to a "worst case" scenario for indirect irradiance caching, so I would switch this off, at least for your rtrace calculation.  It will still be very expensive to compute the light through this system, but you can try something like:

	rtrace -I+ -aa 0 -ad 1024 -as 1024 -ab 10 -lw 1e-4 -lr -12

The other option is to use a more modest irradiance caching operation with the BSDF you have computed.  You do not need to use the system geometry, as it seems the elements are too thick to let direct light through in any case, which was my initial (incorrect) assumption.

Best,
-Greg

> From: Marouane.Boudhaim at ise.fraunhofer.de
> Date: December 10, 2017 8:09:30 PM PST
> 
> Hello Greg, 
> 
> I unfortunately use two computers with different rtrace versions (to speed things up). One has 5.1a and the other 5.1.0. 
> 
> As of the bsdf generation options. It has been generated through genBSDF with only -dim option. I want to note that the BSDF was only used for the 3-phase method, and the system's depth has been neglected (2mm depth seems neglectible in regards to scene's dimensions). 
> 
> Rtrace scene used the real geometry (the one I generated from the BSDF) as I want to validate against it. I didn't use the proxy geometry. I don't know if it answers your question. 
> 
> Thank you for your time! 
> 
> Sincerely, 
> Marouane. 
> 
> 
> Date: Sat, 9 Dec 2017 12:58:18 -0800
> From: Greg Ward <gregoryjward at gmail.com>
> To: Radiance general discussion <radiance-general at radiance-online.org>
> 
> Hi Marouane,
> 
> Which version of Radiance are you using?  (I.e., what does "rtrace -version" say?)
> 
> There are difficulties finding transmitted solar radiation through unproxied BSDF materials before the 5.1 release.  The latest release adds a new calculation called "peak extraction" that attempts to identify strong peaks in the BSDF view component that it treats separately.  The solution is not perfect, but it generally leads to more correct results in such cases.
> 
> Another approach if you are starting from a geometric description of your fenestration and using genBSDF is the +geom option, which includes the system geometry in the XML file.  You can then apply "pkgBSDF" to translate this geometry and surround it with appropriate proxy surfaces, so that your rays will pass through and generate the correct patterns on your interior surfaces, as well as giving you a correct view through the fenestration system.
> 
> If you are using genBSDF, what options did you include?  How did you describe the actual BSDF surface(s) in your model?
> 
> Best,
> -Greg
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