On 27.11.2017 18:59, Alain wrote:

>> This is how it looks without scattering and emission. :-)
>>
>> Both seem to be required for correct colors. But look to the lowest
>> posting in this thread, that is an update and I try out an isosurface
>> there.
>>
>> My need now is, instead of fog, a media that can give me what I need.
>> See the 2nd attached image, it shows the different atmospheric layers I
>> need:
>> - ground fog just reaching above clouds
>> - orange distant layer, hiding the edges of my clouds
>>
>> http://wiki.povray.org/content/Documentation:Tutorial_Section_3.6
>>
>>
>> ---

>> http://www.avg.com
>>
> 
> You have only absorption. You need scattering, NO emission and probably
> no absorption.
> 
> Scattering media interact with light and get illuminated by it. It can
> show, and cast, shadows. In a radiosity scene with "media on", it can
> illuminate it's surrounding from the light it scatters. It can show
> against any background. Think of a cloud, turbid water, dust in
> suspension in the air,...
> 
> Emissive media don't interact with lights and is self illuminated. In a
> radiosity scene, it can illuminate it's surrounding if you use "media
> on" in your radiosity block. Visible against darker background. Think of
> a plasma.
> 
> Absorbing media cause shadow and can hide the parts of the scene behind
> it. It is never illuminated by any lights. Visible against lighter
> backgrounds. Think of dark smoke loaded with carbon particles.
> 
> 
Thank you! That is indeed a very good explanation! It makes me
understanding it better now, well appreciated!

And that is what I like with the POV-Ray community: the great, truly
great and helpful spirit here! After all, we all are pioneers in some
ways with each of our POV-Ray scenes.

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