Dear list
I am trying to get transmission matrix of a shading system with genBSDF. The
system is made from double glazed window and glass louvres with silk screen
print with coverage of 55%. For the window I could used optics2rad to get
the material description without problem but I got problem with the louvres
because Optics5 does not have fritted glass. I guess that I should program
glaze as Jack de Valpine presented 2year ago at the Radiance workshop for
the louvres. However I've got some problems with definition of the frit and
understanding what glaze does.
Briefly what I know about the louvres: glass is SGG Parsol green 8mm and
silk screen print is covering 55% and the colour of frit is RAL 9010 which
is almost pure white.
I am not sure what " Tr Tg Tb Rcr Rcg Rcb Rgr Rgg
Rgb Part " should be used for frit. Does anyone was working with similar
shading and have some values I can used, at least as assumption? Or is there
any way to find those values without actual measurement? Maybe there is some
source which you can recommend me.
Are those values for frit only or is it a glass together with frit? In the
case that it is including also a glass does the glass have to be same as the
clear glass which is needed to be defined in glaze program?
I was also wondering how the transmittance and reflectance is calculated
exactly. As I understand it a transmittance is calculated in the way that
the part of transmittance of the glass with frit is add to the transmittance
of the glass surface without the frit. Is anyhow included that the
transmittance through the frit is further reduced by the transmittance of
the glass if we assume that the frit is on exterior surface.
In the case of a reflectance on a glass surface opposite to the placement of
frit I am even more confused. When I looked into the code of glaze program
the glass reflection is calculated as reflection of the surface opposite to
frit multiplied by coverage plus reflectance of the clear glass which is not
covered by frit. Should I have the glass surface on the frit same as the
clear glass and basically have the reflectance on the glass surface all over
same. Or should I define that the opposite site of the frit as same
reflectance as frit since the ray should go first through the glass and then
will be reflected from the back side of frit?
I guess that the program is simplifying the transmittance and reflectance,
do you know how much it will be different from the reality?
I am not sure if I described my thoughts understandable since since I may
misunderstand several things in graze, so I will be very happy if someone
could clear it up for me.
Thank you very much for any ideas and suggestions.
David