POV-Ray : Newsgroups : povray.advanced-users : Skylight intensity and color Server Time
24 Nov 2024 19:30:26 EST (-0500)
  Skylight intensity and color (Message 1 to 3 of 3)  
From: Bjorn Jonsson
Subject: Skylight intensity and color
Date: 22 May 2005 08:54:30
Message: <MPG.1cfa91442b989354989694@news.povray.org>
Does anyone know where I can find information on the intensity and color 
of skylight as a function of solar elevation angle, including when the 
sun is below the horizon ? Needless to say this is highly variable 
depending on the amount of aerosols etc. but I'm looking for something 
fairly 'typical' (I'm assuming a clear sky, i.e. no clouds). I'm also 
interested in the overall contribution of skylight to a scene's 
brightness relative to sunlight.

-- 
Bjorn Jonsson
http://www.mmedia.is/bjj


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From: Florian Brucker
Subject: Re: Skylight intensity and color
Date: 22 May 2005 10:06:56
Message: <42909200$1@news.povray.org>
I'm not sure how physically correct it is, but SkyLight could be your
choice for POV-Ray. It has been included in LightSys, which offers
additional macros for lights and light calculations. You can find it at

	http://www.ignorancia.org/lightsys.php

HTH,
Florian
-- 
camera{look_at-y*10location<8,-3,-8>*10}#local a=0;#while(a<999)sphere{
#local _=.01*a-4.99;#local p=a*.01-5;#local c=.01*a-4.995;<sin(p*pi)*5p
*10pow(p,5)*.01>sin(c*c*c*.1)+1pigment{rgb 3}}#local a=a+1;#end
/******** http://www.torfbold.com ******** http://www.imp.org ********/


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From: Jaime Vives Piqueres
Subject: Re: Skylight intensity and color
Date: 23 May 2005 04:54:01
Message: <42919a29$1@news.povray.org>
Bjorn Jonsson wrote:
> Does anyone know where I can find information on the intensity and
> color of skylight as a function of solar elevation angle, including
> when the sun is below the horizon ? Needless to say this is highly
> variable depending on the amount of aerosols etc. but I'm looking for
> something fairly 'typical' (I'm assuming a clear sky, i.e. no
> clouds). I'm also interested in the overall contribution of skylight
> to a scene's brightness relative to sunlight.

   I use the "skylight.inc" implementation of the skylight model by
Philippe Debar, which I included in Lightsys as "CIE_Skylight.inc", but
it does not solve completely the problem you pointed out, as it does not
contains a proper sunlight model, and the returned "SunColor" looks more
like the color of the skylight at sun position.

   My best solution for the moment is to use the Blackbody(K) macro
contained on Lightsys, with variable temperature and intensity depending
linearly on the altitude, as I've not found any pointers on how to do it
more realistically.

   Hope this helps...

--
Jaime


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