In article <4081ceec$1@news.povray.org>,
 Dan P <dan### [at] yahoocom> wrote:

> > The Earth doesn't really add anything by radiosity alone so I'll add a light
> > source to it.
> 
> Right; it's too far away.

Distance has little to do with it, it is the area of sky covered and 
brightness per unit area that counts. The diameter is about 3.6 times 
that of the moon, the sky area covered is almost 13.5 times greater. The 
moon's albedo is less than Earth's, between 7% and 12% compared to 30%. 
(The lunar surface reflects light preferentially in the direction it 
came from, so it appears brighter when nearly full.)

This all means that Earthlight is much brighter than moonlight. It's 
still very little in comparison to direct sunlight, but it can 
contribute to shadowed areas if the viewer's not looking at a bright 
object, and will be very significant at night on the near side. And it's 
practically all due to radiosity, diffusely scattered sunlight, though 
an area light might be more accurate than any but very high radiosity 
settings.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: <chr### [at] tagpovrayorg>
http://tag.povray.org/

Post a reply to this message