In article <3ee746d0@news.povray.org>,
 "Anto Matkovic" <ant### [at] matkoviccom> wrote:

> - POV-Ray have a default global ambient set to 1 (rgb 255), in dinstinction
> to many scanlines, where this is usually zero or dark grey. If you find on
> IRTC site some images with a dark, well saturated colors like an old
> painting, this can be work of Jaime Vives Piqueres. He was used a global
> ambient color set to zero.

This value is actually a multiplier for the finish ambient values. If 
set to 0, it is the same as setting all ambient values in the scene to 
0. 0.5 is equivalent to halving them. Or you could use a color to give 
the scene a specific color cast. It really doesn't do anything you can't 
do otherwise, and setting it to 0 makes it impossible to create glowing 
objects with radiosity. A better solution is to adjust the default 
texture values:
#default {finish {ambient 0 diffuse 1}}

This way, objects have no ambient light unless you specify it, and the 
pigment alone specifies the diffuse reflection. However, if you find out 
you *do* need ambient, for a glowing light bulb for example, you can 
still use it. You can also set the other texture items this way...for 
example, you could set the default pigment to be a seizure inducing 
candy-striped neon green and hot pink, which will quickly alert you if 
you forget to specify a pigment.


> - POV values can go over 1 or lower to zero (something like rgb 788 or
> rgb -200; not too much usable, but you may know that)

Values greater than 1 are useful, especially with more accurate light 
simulation features such as radiosity. Real-world scenes have great 
variation in lighting, not a limited range.


> - POV materials haven't independent  highlights color, this depend on the
> light color. In case of metallic finish, this do not depend (more precisely,
> 'near to do not depend').

With metallic highlights, the surface color affects the highlight color. 
The light color is still important though.

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

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