[Bf-cycles] max bounces

[Daniel Salazar - patazstudio.com]

I've also found strange how you can make cycles calculate 200 bounces
with not much apparent slowdown, wonder why..
Daniel Salazar
patazstudio.com


On Thu, Nov 6, 2014 at 2:42 PM, David Fenner <d4vidfenner at gmail.com> wrote:
> Hi Thomas, thanks for the reply. I'll try to find time todar or tomorrow at
> most to do a more clear test, with pics and blend file. I'm pretty sure I
> tested it with 1 min bounce all the time though, but I'll run them again and
> upload in a more organized way.
>
> Thanks again,
> David.
>
> 2014-11-06 17:37 GMT-03:00 E. David Ferriman <dferriman at gmail.com>:
>
>> Awesome! Thanks!
>>
>> On 11/6/2014 3:33 PM, Thomas Dinges wrote:
>>
>> Hi David,
>> that is weird, I cannot think of a reason for this at the moment.
>>
>> The way the feature works, is that it checks if the Light Max Bounce
>> setting is greater than the current bounce, if that's the case it skips
>> evaluating the lamp.
>> Did you use the Pathtrace or Branched Pathtrace integrator? Also what were
>> your global min bounces? If they differed from the global max bounces, it
>> might be worth to check again with these 2 values being the same.
>>
>> Thomas
>>
>> Am 06.11.2014 um 14:00 schrieb David Fenner:
>>
>> Hi Thomas, thanks for the commit yesterday, to control bounces per light,
>> very nice!!
>>
>> Been doing some tests here, and I ran into a very strange scenario:
>>
>> When I have 3 or more max diffuse bounces in global render settings,
>> reducing per lamp bounces have little to no impact in render times, even if
>> set to 0 bounces. However, when I have only 2 max diffuse bounces in render
>> settings, lowering per lamp bounces have a very big impact on render times,
>> reducing them almost as much as if I lowered global diffuse bounces on the
>> same quantity. It's like there was some sort of threshold at 2 global
>> bounces. For example:
>>
>> (on a simple diff scene with one lamp)
>>
>>
>> Global Max Diff Bounces = 0
>> Lamp bounces                 = 0
>> Render Time: 4.7 sec
>>
>>
>> Global Max Diff Bounces = 3
>> Lamp bounces                 = 1024
>> Render Time: 10 sec
>>
>>
>> Global Max Diff Bounces = 3
>> Lamp bounces                 = 0
>> Render Time: 9.7 sec   (almost the same as before)
>>
>>
>> Global Max Diff Bounces = 2
>> Lamp bounces                 = 2
>> Render Time: 8.5 sec      (lower rendertime thanks to one less bounce)
>>
>>
>> Global Max Diff Bounces = 2
>> Lamp bounces                 = 0
>> Render Time: 4.9 sec       (before it didn't even care, yet for 2 bounces
>> and below its almost as there where no global bounces)
>>
>>
>> It's great, with 2 global diff bounces and below the gains of lowering per
>> lamp bounces are almost as big as if lowering global diffuse bounces, so
>> having only a few lights with GI can increase your rendertimes amazingly,
>> however,  with 3 global diff bounces and over there is strangely almost no
>> gain, even when all lamps have 0 bounces.
>>
>>
>>
>>
>>
>>
>>
>>
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>>
>>
>>
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>>
>> --
>> E. David Ferriman
>> Web Designer
>> dferriman,com
>> dferriman at gmail.com | (614) 260-7238
>>
>>
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