[Radiance-general] glazing modelling

[Marija Cvetkovic]

Hi Jack,
Thank you for the fast answer.
 I just have few comments:

>> PROCEDURE1
>> Problem:
>> *Glass reflectance is calculated implicitly, and values from Optic5
>> database don't have any effect.
>> This can be solved by using trans.cal functional file, and changing index
>> of refraction to obtain appropriate reflectance.

> As I read "trans.cal" this is for converting from transmittance to
> transmissivity, the latter value is used for the radiance "glass" material
> type. I believe that the "glass" material that is output from Optics
> accounts for this translation. I think that maybe Chas Erhlich could
> confirm this?

Yes, this conversion is taken into account when glazing is exported.
I meant trans2.cal, not trans.cal. My idea was to use a trick I've found in
some Greg's mail:
To define glass with transmittance .85 and reflectance 0.5, run "calc
trans2.cal" in the ray/src/cal/cal directory and enter:
       Tn = 0.85
       Rn = 0.05
Typing in "n" and "tn" will give you these results:
       n
       $1=1.39992615
       tn
       $2=0.894736842

> Note though, quoting Greg from the file, that trans.cal is for an
> "infinite series solution for an uncoated pane of glass." This is a
> solution for a single pane only. I am not sure that adjusting the index of
> refraction is a valid way to "adjust" the reflectance and it still would
> result on the same reflectance on both sides of the material. Most glass
> systems that use coated glass have different reflectances on the outside
> and inside.

You are right, so I suppose this 'simply glass' option is definitely not for
use.

>> 2.What is the format of input file for glaze.csh script?
>
> The input file should look something like the following it has a header
> line followed by one line per glazing material type:
>
> Surface   Tr   Tg   Tb   Rcr   Rcg   Rcb   Rgr   Rgg   Rgb   Part
> <surface name>   <r trans>   <g trans>   <b trans>   <r coated refl>   <g
> coated refl>   <b coated refl>   <r glass side refl>   <g glass side refl>
> <b glass side refl>   <boolean switch [0 or 1] to indicate if material can
> have partial coverage, such as a frit>
>
> As I recall this file is pretty sensitive to spacing of the values!
>
Yes, I've already had that problem, and that is the reason why I've asked
for the format definition.
The other problem occurs when I put only one glazing definition into the
file. Glaze script doesn't report error, but new material isn't added to
list of available surfaces!? Do you have an idea why it is happening?

Thanks again,
marija