We want to simulate a red coated glass in Radiance. The UV-VIS spectroscopy analysis was conducted and optical characteristics of the red glass including transmittance and absorbance were recognized. Then, the transmissivity of the glass sample was calculated based on the following formula.
Transmissivity = (sqrt (0.8402528435 + 0.0072522239 * Transmittance ^ 2) - 0.9166530661) / 0.0036261119 / Transmittance)
For example, the Transmittance of red colored glass is 48 % and the transmissivity is 0.5232.
We want to define this glass in Radiance.
We can defined the red glass in two methods in Radiance. I appreciate if you clarify which one is correct.
1-First method
mod glass Red_Transmittance_48
0
0
3 0.5232 0.5232 0.5232
2-Seconed method
mod glass Red_Transmittance_48
0
0
3 0.5232 0 0
In the second way, we remove the parameters of gtn and btn because of red color of the sample.
On the other hand, some scholars suggested to add the wavelengths of lights (red, green, blue) in the definition of glass material in Radiance and the calculation of transmissivity. However, it is not clear at all how we can consider the wavelengths in our calculation since there is not the wavelengths parameters in the transmissivity formula.
Now my question is , because of the color of glass should we consider the wavelengths of lights (red, green, blue) in transmissivity calculations or in the definition of glass material in Radiance? If yes, I appreciate if you introduce the formula and the method that we can use.
Negar Heidari Matin,
Sorry that your question is unanswered for more than a month now, and I don't if any formula or method exists as well. So, probably I would recommend Shiv Prakash Singh, Basudeb Karmakar, Gaurav Gupta to enlighten you in this regard.
Thanks & regards
MN
Hi Negar and Mithun,
I may not be able to answer your question perfectly, but I am trying to put my opinion within the limit of my understanding as follow.
The best way to determine/simulate the color radiation from your sample is to plot the CIE color diagram. I always found the CIE plot is interesting to understand the color emission of your sample. From this diagram, you will find whether the sample emits red color or not. There is some software is available to plot the CIE diagram. I think, for this, you need the luminescence data of your sample. I am not sure about the transmitivity data can be used for this plot. You will find some information from the following links
https://www.researchgate.net/post/How_can_I_plot_CIE_chromaticity_diagram
https://www.mat.univie.ac.at/~kriegl/Skripten/CG/node9.html
Sorry that I could not answer you in a more convenient way.
Thanks and regards,
Shiv
Thanks Shiv, Negari & Mithun,
I would like to mention in addition to Shiv, that there're two parameters which we could estimate utilising CIE plot.
A. Absorption spectra as input should give Absorptivity.
B. Emission spectra as input will give Emissivity.
The coordinate of CIE plot is the standard method that can be exploited from the spectrum.
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