[Radiance-general] Sun Color

[Greg Ward]

Hi Marcus,

This can be done with an appropriate insertion of rcalc in your 
Radiance command.  In the scene file, you would modify your gensky line 
to read:

!gensky 6 21 12 | rcalc -p -i sunlight.fmt \
	-e 'sr=1.035*si;sg=1.003*si;sb=0.826*si' \
	-o 'void light solar 0 0 3 ${sr} ${sg} ${sb}'

The color for the sun is converted from the CIE (x,y) chromaticity for 
standard illuminant B, which is (0.3485,0.3517).  The file 
"sunlight.fmt" must contain the following:

void light solar
0
0
3 ${si} ${si} ${si}

You'll need the latest version of rcalc (3.6.1 release), as previous 
versions did not have the -p option.

Hope this works for you.
-Greg

> From: "Marcus Jacobs" <marcdevon at hotmail.com>
> Date: January 6, 2005 8:00:39 AM PST
>
> Dear Group
>
> Does anyone here know how to alter or adjust gensky's sun color?  I 
> guess what I am looking for is a color that is warmer that the color 
> that I am achieving now. This is for asthetic purposes but I want a 
> solution that is physically accurate. I have tried altering the day 
> and time of day to achieve this but it seems that only the angle, 
> height, and intensity of the sunlight is changed and not the color. I 
> don't mind hard coding it in the application if it necessasary if it 
> isn't too messy. Any suggestions?
>
> Marcus