[Radiance-general] How to calculate the ( rtn gtn btn ) values of the material type glass ?

[marina aviles]

Hello all,

i don´t know haw can you get the values rtn, gtn and btn of the material
description "glass":

void   glass  id
0
0
3   rtn  gtn  btn

from some glass samples.

I have measured their transmittance values with a Spectrometer ( Varian -
Cary 5000) in the field 350 - 780 nm wavelenght and have calculate the
Transmittace.
Should I then calculate the transmissivity from the transmittance by
computing

tn = (sqrt(.8402528435+.0072522239*Tn*Tn)-.9166530661)/.0036261119/Tn  ?


and, in this case, how can I get the values rtn, gtn and btn?

Thanks a lot,

Marina
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