> Hey Bald Eagle,
> 
> first, it's funny you discovered the time zone thing ... actually there is
> really
> that 1 year + difference between Germany and New Hampshire. But it is a secret,
> so I changed the date to 2017 for now ;)
> 
> The statement of Alain is actually documented here:
>      http://www.povray.org/documentation/view/3.6.1/422/
> (section 2.6.2.3.4 Multiple Density vs. Multiple Media) And he is absolutely
> right,
> the densities multiply while the media add.
> 
> So I did that ... the good thing: it works! ... the bad thing: if I add the
> glowing auras for the number of emitters I planned (50 per unit cell) I am
> getting
> the following error:
> 
>      File 'phc_and_excitation_enhancement.pov' line 372: Parse Error: Expected
>       'numeric expression', undeclared identifier 'Trans_vec' found instead
>      Fatal error in parser: Cannot parse input.
>      Render failed
> 
> I'm kind of shocked :D So there seems now way around this except for compiling
> Pov-ray myself. So I'll let it be :) The workaround: I'll use the multiple media
> technique only for the field render and stick to the individual object approach
> for the emitters. (This may cause some artifacts which I may erase using
> Photoshop).
> 
>> So, it sounds to me like what you need to do is have a media statement for each
>> of your spheres.
>> It looks like your box is 100 x 100, so perhaps you just adjust the drop-off in
>> your exponential decay formula to compensate for that 100x scaling of the media
>> unit cube.
>> The spheres just get placed in that 100 x 100 box as well instead of in a unit
>> cell.
> 
> This turned out to be unnecessary because Pov-ray seems to define the density
> in a unit cube no matter what size the container has (don't ask me why). Somehow
> it worked out with the same transformations as before!

The spherical pattern fits within an unit sphere by definition.
The boxed pattern is indeed defined in an unit cube going from 
<-1,-1,-1> to <1,1,1>.
There is the cylindrical pattern that fill an unit cylinder around the Y 
axis and the planar pattern that extend +- 1 unit fron the X-Z plane.

If you use some other patterns, you'll see that they actually completely 
fill any container used.

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