[Radiance-general] transmission/transmissivity

alexis Loubeyre aloubeyre2 at hotmail.com
Thu Nov 18 07:56:55 PST 2010


Hi everyone
 
In radiance manual, when you want to create a glass material, we use this function:
 
void glass id
0
0
3 rtn gtn btn
 
 
where tn is the transmissivity which comes from this formula:
 
tn = (sqrt(.8402528435+.0072522239*Tn*Tn)-.9166530661)/.0036261119/Tn
 
where Tn is the transmittance.
 
For example, if i have light transmission for a window equal to 60% (given by a manufacturer), do i have to calculate tn with Tn =0.6
 
and then put my results in the function, so with this example we'll have: tn = 0.65 with Tn = 0.6?
 
void glass id
0
0
3 0.65 0.65 0.65
 
Other type, other question:
 
for a mirror, what is the default specularity if I define default mirror with this function:
 
void mirror window
0
0
3 0.965 0.965 0.965
 
Thank's a lot for your help.
 
Regards
 
Alexis
 
 
  		 	   		  
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