On 30-4-2017 18:30, Alain wrote:
> Le 17-04-30 à 07:05, Thomas de Groot a écrit :
>> On 30-4-2017 9:48, Thomas de Groot wrote:
>>> In fact, the differences are more subtle. For the cube, compare the
>>> shadows of dragon and egg: their edges show the stone's translucency. In
>>> my next render I hope to show this better.
>>>
>>
>> In this render:
>>
>> - Dragon: no SSLT
>> - Floor: no SSLT
>> - Cube: SSLT with 5*translucency vector (was 2* in earlier example)
>> - Egg: SSLT with 3*translucency vector (was 2* in earlier example)
>>
>> The cube is showing markedly more translucency in the shadows cast on
>> it. I see not much difference in the egg, although if I increase the
>> translucency exaggeratedly (*100 for instance) the effect becomes
>> distorted.
>>
>> Question: In the wiki about SSLT it is said: "The effect doesn't scale
>> with the object". Does this mean that SSLT works in the same way as a
>> scattering media where the amount of scattering has to be compensated
>> for the amount of media object's scale? It appears so to me at least
>> although this is not mentioned in the wiki.
>>
>
> It does work similarly to medias, both emissive, absorbing and scattering.
>
> So, if you scale your scene by 10 and want SSLT to look the same, then
> you need to multiply your SSLT vector by 10. Alternately, you can
> increase mm_per_unit by the same amount in the global_settings block.
>

OK. Only difference would be that with scattering media (for instance) 
you have to /divide/ the scattering vector by the scale of the container 
to get the same result, but I get the point indeed.

I am a bit wary about the mm_per_unit and prefer not to touch it too 
much, especially if different objects have different scales.

-- 
Thomas

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