Tom Melly wrote:
>
> So, one should divide the pigment by the ambient value used?

No. Use realistic color values. Povray does the clipping automatically.
It affects only display. It's the same thing what happens with printed
images. The image cannot be brighter than the paper it's printed on.

> With the following code, how do I get my glowing ball (!) to illuminate the
> surrounding sphere?

The problem here is that the source is small when seen from
the outer surface and all the rad sample rays miss it. Ambient
sources require higher count and recursion_limit than light
sources and are thus slower.

I also reduced the radius to make the source more "visible"
to the rad sampling.

#version 3.5;
#include "colors.inc"

global_settings{
  assumed_gamma 1.0
  radiosity{
    pretrace_start 0.04
    pretrace_end 0.01
    count 500
    recursion_limit 1
    nearest_count 10
    error_bound 0.5
  }
}

camera {
  location  <0.0, 0, -4.0>
  look_at   <0.0, 0.0,  0.0>
}

sphere{0, 20  pigment{White} finish{diffuse 0.6 ambient 0}}
plane{y, -1 pigment{White} finish{diffuse 0.6 ambient 0}}

#declare myAmbient = 100;
sphere {
  0.0, 1
  pigment {Red}
  finish{diffuse 0 ambient myAmbient}
}

_____________
Kari Kivisalo

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