[Bf-cycles] max bounces

Matthew Heimlich matt.heimlich at gmail.com
Thu Nov 6 22:38:57 CET 2014


That's due to the Russian roulette that will randomly kill rays after they
reach the minimum value, I believe.
On Nov 6, 2014 4:13 PM, "Daniel Salazar - patazstudio.com" <zanqdo at gmail.com>
wrote:

> 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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> >> Bf-cycles at blender.org
> >> http://lists.blender.org/mailman/listinfo/bf-cycles
> >>
> >>
> >>
> >>
> >> _______________________________________________
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> >>
> >>
> >> --
> >> E. David Ferriman
> >> Web Designer
> >> dferriman,com
> >> dferriman at gmail.com | (614) 260-7238
> >>
> >>
> >> _______________________________________________
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> >> Bf-cycles at blender.org
> >> http://lists.blender.org/mailman/listinfo/bf-cycles
> >>
> >
> >
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> >
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