[Radiance-general] mirror material ignoring modifier in virtual source calculations

[goodriver laurus]

------------------------------

Dear Greg,

Many thanks for for quick response. I am trying to use a modified
mirror like the one posted on 17 March 2008 in order to emulate the
angular-dependent reflections from a glass:

void glass glass_alt_mat
0
0
3 0.96 0.96 0.96

void brightfunc glass_angular_effect
2 A1+(1-A1)*(exp(-5.85*Rdot)-0.00287989916) .
0
1 0.08

glass_angular_effect mirror glass_mat
1 glass_alt_mat
0
3 1 1 1

I use this material to quantify in a top view the illuminance on the
ground due to reflected light from vertical windows (therefore not
looking at the glass, but just at the reflections). The calculation is
been done with rpict -i -ab 0 -dr 1. I have also tried other values
for the parameters but the results are the same.


I would expect the reflections to vary in value depending on the angle
of incidence on the glass. However, all reflections seem to be of the
same intensity, actually 100% reflective like in an ideal mirror.
I wonder if the issues I am having may have to do with the way I am
using rpict or if there is a more fundamental error. I have tried
testing this issue in Radiance 4.2 for Windows to see if could have to
do with the platform or with recent issues with the m_mirror routine,
as posted a few days ago, but the results are again the same.

Thanks and best regards,

Rioboo

Hi Rioboo,

It helps when you give a specific example.  What is your material
definition, and what is it doing that disagrees with your
expectations?

The mirror material will ignore its modifiers in the case when you
have given an alternate material type.  This will be called instead
when viewed directly.  The modifiers to the mirror itself will only be
used for calculating the virtual source contributions.

Best,
-Greg

>* From: goodriver laurus <rioboo at gmail.com <http://www.radiance-online.org/mailman/listinfo/radiance-general>>
*>* Date: June 12, 2016 4:16:03 PM PDT
*> >* Dear all,
*> >* I am currently having problems using mirror materials with
brightfunc modifiers for virtual source calculations. The mirror
material seems to ignore the modifier. I've seen in recent post that
there seems to be a bug with in the m_mirror routine and I wonder if
that is the problem or if it could be something else.
*> >* Thanks,
*> >* rioboo*
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