On 01/22/2018 05:21 AM, clipka wrote:
> Am 21.01.2018 um 21:56 schrieb William F Pokorny:
> 
>> Is this the expected behavior for media_attenuation?
> 
> The documentation for the feature specifically mentions "fog or
> atmospheric media" (as opposed to object-contained media), so I'd say,
> yes, that's the intended behaviour. Other portions of that same docs
> section refer to "the fog or media", but I'd take that to be just a lazy
> reference to the more precise term used earlier.
> 

Thanks.

Does our documentation then push the use of the media container too much 
if using scattering media?

It looks to me like it's probably not the right thing to do if a user 
doesn't need/want media attenuation. Global media in my testing is quite 
a bit faster than any container with scattering media - except those 
where the light is inside the container.

--- media_attenuation on
1541.79user 0.67system 12:56.48elapsed (global media. outside postion)
                                        (Media Samples: 4,295,692,846)

--- media_attenuation off
403.22user 0.04system 3:22.24elapsed  (container. outside postion)
404.69user 0.05system 3:22.99elapsed  (Media Samples: 1,064,722,061)

32.04user 0.01system 0:16.67elapsed  (global media. outside postion)
32.10user 0.01system 0:16.67elapsed  (Media Samples: 58,877,772)

8.71user 0.01system 0:05.00elapsed  (container. inside postion)
8.63user 0.01system 0:04.94elapsed  (Media Samples: 11,828,518)


While I'm happy to know I can contort my media containers to contain the 
light for really fast scattering media renders, I do wonder a little why 
media attenuation is always off in that case.

Instead of contorting the container shape, would a media {} block 
'media_attenuation off' capability could be useful for those wanting to 
use scattering media and attenuation for final renders, but wanting fast 
working renders?

While you can sort of fake a media initially at much better performance 
using emitting media over scattering, you don't get a very good feel for 
the final scattering look of any given media-density that way.

Bill P.

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