nemesis nous apporta ses lumieres en ce 2007/11/11 16:25:
> =?ISO-8859-1?Q?=22J=E9r=F4me_M=2E_Berger=22?= <jeb### [at] freefr> wrote:
>>  I'd be really interested to see such a scene if you could make one,
>> but you can't (unless you use the "no_reflection" keyword of
>> course).
> 
> global_settings {
> 
>         ambient_light 0
>  radiosity { brightness 1.2 }
> 
> }
> 
> 
> 
> union {
> 
>  plane { y, -1 pigment { rgb 1 } finish { ambient 6 } }
> 
>  sphere { -x, 1 pigment { rgb x } }
> 
>  sphere { x, 1 pigment { rgb y } finish { reflection 1 }}
> 
> 
> 
>  translate z*5
> 
> }
> 
> 
> I can't see a thing.  Reflections or otherwise.
> 
>> I have made some test scenes with pure ambient lighting
>> (neither light sources nor radiosity) and reflective materials and
>> the reflections showed just fine.
> 
> yes, but you know ambient light is by itself faking a constant ambient lighting,
> don't you?  That's the hidden light by which povray is tracing the scene.  No
> lights, no reflection, nor image. nothing...
> 
> Let there be light! :)
> 
> 
> 
It's obvious why you don't see anything: you set "ambient_light 0" in your 
global_settings, whitch effectively negate your high ambient object.
The ambient_light should ONLY be used if you want to alter the coloration of the 
ambient components for the whole scene.

ambient_light is multiplied with the ambient part of every finish. Anything 
multiplied by zero equals zero.
Realy, in any radiosity scene lighted by ambient object, you MUST NEVER set 
ambient_light to 0.
Rerun your sample scene as follow:

#default{finish{ambient 0 diffuse 1}}
global_settings{radiosity{}}
union {

  plane { y, -1 pigment { rgb 1 } finish { ambient 1 } }

  sphere { -x, 1 pigment { rgb x } }

  sphere { x, 1 pigment { rgb y } finish { reflection 1 }}



  translate z*5

}

Now, you can see everything. I've reduced your ambient 6 to 1 to prevent 
oversaturation.

-- 
Alain
-------------------------------------------------
Real Time, adj.:
     Here and now, as opposed to fake time, which only occurs there
and then.

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