On 04/04/2011 03:19 PM, Alain wrote:

>> On 04/04/2011 07:11 AM, Jim Holsenback wrote:
>>> On 04/03/2011 06:55 PM, Alain wrote:

>>>>> Am I wrong to expect a light_source that's been included in a
>>>>> light_group to interact with scattering media? Also I've noticed in
>>>>> the
>>>>> scene stats that it's reporting one less light source when it's
>>>>> included
>>>>> as part of a light_group ... wuz up wid dat?
>>>>
>>>> Light from a light_group will only illuminate scattering media that is
>>>> part of it's group, BUT, the absorbtion from such media will affect the
>>>> light even if it's not in the light_group.
>>>
>>> ah ... thanks the one thing I didn't try. I didn't see anything in the
>>> docs, so I'll double check and make an addition if I come up empty
>>> handed.
>>>
>>
>> Didn't see anything, so this section:
>> http://wiki.povray.org/content/Documentation:Reference_Section_6.1#Scattering
>>
>>
>>
>> now has a referral (at the bottom) back to the Light Groups section were
>> I reworked that section to include the caveat.
>
> There is nothing that say that specificaly, but, we do know that a
> light_source don't illuminate ANYTHING outside of it's group. So, we can
> deduct that it won't illuminate any scattering media that is not
> included in the group.
>
> Likewise, if some object is between the grouped light_source and an
> object from the group, that outside object WILL cast a shadow on the
> object in the group.
>  From that, we can deduct that both absorbing media and scattering media
> will also atenuate the light, and cause some shadowing.
>
> Again, the documentation don't mention it explicitely in relation with
> media, but consticency demands it to be that way.

I guess it just wasn't that obvious to me at first, so I guess there's 
now harm in the addition I've made ... LOL no need to rub it in ;-)

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