[Radiance-general] Solved: defining an uniform sky, rgb weighted light sources

Lars O. Grobe akilog at nus.edu.sg
Tue Dec 30 01:24:20 PST 2008


Sorry,

I think I messed up a lot here, following some random results of rtrace 
runs. First, the results of rtrace illuminance with a sky dome defined 
as light are more or less random. So the fact that I got a result close 
to what I expected only led me to the wrong direction.

Defining glow, there is no need for multiplying anything for the 
colorimetric balance, as I assume a neutral white light source. The 
multiplication only has to be done when getting from radiance (which is 
in RGB channels) to illuminance. So I have either to use a glow with RGB 
1 1 1 and modify it with the brightfunc from gensky (as is usually done) 
or directly use the (neutral white) radiance calculated dividing 
luminance by 179 for the glow material in case of an uniform sky (RGB 
17.8 17.8 17.8).

Results are fine (9998.5 for the simple glow and 9987.6 for the skyfunc 
sky), I forget about my light-modified source, and hope that noone else 
spent time on my rather silly question...

CU Lars.



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