[Radiance-general] parameters for dds (rtcontrib) using BSDF material

[Andrew McNeil]

Hi Nassif,
It would be helpful to have more information about your scene and BSDF (and
what is dds.bash??)

I can think of two possible causes of your error:

1 - One of the problems with the Window BSDF data is that they have low
resolution.  The averaging of flux over a BSDF patch causes the direct
sunlight to smear.  The resulting sun patch is bigger and less bright.
 This is illustrated in figures 12 & 13 of this paper:
http://gaia.lbl.gov/btech/papers/4414.pdf

2 - Using the BSDF material in a daylight coefficient simulation can under
estimate illuminance from direct sun.  If your BSDF is for clear glass,
then it should be possible to improve it by setting ss to > 1 (like maybe 8
or 10).  I think this works with rtcontrib...

You might also consider generating a high resolution tensor tree BSDF using
genBSDF.  It'll definitely help with problem 1, and would help with problem
2 if your BSDF is clear glass.

Regardless though, I'd suggest 3-phase method for anual simulations using
BSDFs.  It is much better for non-specular glazing.

Andy


On Mon, Jul 16, 2012 at 12:16 AM, nassif nassif <nynassif at gmail.com> wrote:

> Hallo,
>
> what is the best parameters for dds.bash when using BSDF materials?
>
> Well, I am testing a simple room with BSDF material ( which i obtained
> using windows7beta); but the results are not convincing. it ranges +-20 %
> from what i was expecting.
>
>
>
>
> N.B: the parameters i used before for my annual simulations is:
>
> *rtc="-ad 8192 -lw 2e-12 -n $cores" # render-options *( and it works
> perfectly with glas material)
> *
> *
> thx for your support
>
> --
> *N.Nassif
>
> Lighting Designer***
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>
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