[Bf-cycles] ray depth

[David Fenner]

Well that was the question, if it was possible to skip bounces of some
lights even when other lights have GI. So it isn't possible? if for example
a scene with 10 lights all with bounces renders in 5 minutes, and the same
but globally no bounces renders in 2 minutes, then what you are saying is
that it is inevitable that if only 1 of the 10 lights have bounces the
scene will always render in the same 5 minutes if GI is used globally (Even
when 9 of 10 lights don't bounce)?? That is the way it is now, I was hoping
that even when GI is globally activated, as long as we started reducing
bounces on the lights that don't need them render times would decrease.




2014-10-06 15:47 GMT-04:00 Brecht Van Lommel <brechtvanlommel at pandora.be>:

> I understand the use case, GI with some auxiliary lights that do not
> use GI. But the tests being done here are not representative of that,
> the main speedup you are seeing in that test is because you're
> skipping bounces that you can't skip if you need GI for other light
> sources.
>
> On Mon, Oct 6, 2014 at 8:50 PM, David Fenner <d4vidfenner at gmail.com>
> wrote:
> > Hmm I don't understand what you mean brecht... I never said anything
> about
> > wanting no global bounces at all, in the first mail I explained that
> usually
> > some lights (like environment) need GI but many auxiliary lights used to
> > "paint" polygons don't. For example, think of a scene that has 2 lights
> with
> > GI, and 8 lights (rims, face aux, eye aux, some torch, whatever) don't
> need
> > GI, and in fact GI works worse visually. In this scene there would be no
> > gain at all by making these 8 lights not bounce, but since they don't
> > bounce, can't these rays not be calculated to make it faster?
> >
> > Please check first mail, the idea is to make it easier to make some
> lights
> > not bounce for artistic control and that this also helps to optimize
> speed,
> > since they don't bounce... I don't even know if its possible, but I do
> > believe that a scene with 8 lights bouncing should render slower than one
> > with 1 light bouncing (of 8), or this is not possible with pathtracers??
> >
> >
> > 2014-10-06 13:49 GMT-04:00 Brecht Van Lommel <brechtvanlommel at pandora.be
> >:
> >
> >> Well yes, it would be nice if Cycles could automatically detect when it
> >> can set global bounces to 0, but you're not gaining any new capabilities
> >> this way. I imagine that if you want no light bounces at all, then you
> would
> >> have probably just set global bounces to 0, rather than going through
> the
> >> trouble of changing all lamps, emissive surfaces, volumes, ambient
> >> occlusion, the world shader, and whatever else in the scene might be
> >> emitting light.
> >>
> >> There are various optimizations possible here, but this specific case
> >> doesn't seem all that helpful for a production scene?
> >>
> >> On Mon, Oct 6, 2014 at 1:52 PM, Greg Zaal <gregzzmail at gmail.com> wrote:
> >> > Done some tests too and David is right.
> >> >
> >> > 128 bounces, 5:14 - http://i.imgur.com/XFdhp9l.png
> >> > 128 bounces with Ray Depth trick, 5:11 -
> http://i.imgur.com/p8kL5ki.png
> >> > 0 bounces, 4:10 - http://i.imgur.com/xQdrSQD.png
> >> >
> >> > Nodes used for one of the lamps: http://i.imgur.com/MBsi7hh.png (also
> >> > tried
> >> > http://i.imgur.com/htdCsxi.png - made no difference)
> >> > Blend file: http://pasteall.org/blend/31928
> >> >
> >> > Cheers,
> >> > Greg
> >> >
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> >> >
> >>
> >>
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