[Sidefx-houdini-list] H13 Linear lighting/rendering

jason slabber jason.slabber at gmail.com
Fri Nov 22 05:45:25 EST 2013


yip agreed, SESI can't guess, but having a more or options by default can
make life easier sometimes,
like in XSI(back in the day when I used to use it) had options for Auto,
linear, sRGB, or custom gamma.
Auto works well most of the time, but making "automatic" assumptions in a
pipeline doesn't always work out. :)

J


On Fri, Nov 22, 2013 at 12:22 PM, Jordi Bares <jordibares at gmail.com> wrote:

> On those very strange cases, treat the texture as linear, do your special
> thing on the shader should work like a charm.
>
> Jordi Bares
> jordibares at gmail.com
>
> On 22 Nov 2013, at 07:57, jason slabber <jason.slabber at gmail.com> wrote:
>
> > Hey Peter
> >
> > Have you brought this up with SESI?
> > Just wondering cause we would also like to have our own control
> > over texture colorspace. Not just auto and linear, seems a bit
> limiting...
> >
> > J
> >
> >
> > On Thu, Nov 21, 2013 at 7:32 PM, Peter Bowmar <pbowmar at gmail.com> wrote:
> >
> >> Hi Craig,
> >>
> >> Basically Houdini assumes non-8 bit file formats are encoded sRGB so
> >> it linearizes them (gamma .4545) on ingestion via (for example) the
> >> vex texture() call. It assumes 16/32 bit are linear (gamma 1 as you
> >> say) and uses them straight up.
> >>
> >> I think it's very useful for the home user or smaller studio but we
> >> apply LUTs to everything and control via pipeline what textures are
> >> encoded as (displacement for example might be 8 bit but linear, though
> >> that's unusual) so SESI have added some env vars to turn it all off if
> >> you want to manage it yourself.
> >>
> >> However, in a nutshell, yes, leave your viewer at gamma 2.2 since
> >> renders will be "linear" i.e. gamma 1.0 internally.
> >>
> >> Cheers,
> >>
> >> Peter B
> >>
> >> On 21 November 2013 09:05, Craig Hoffman <craigleehoffman at aol.com>
> wrote:
> >>>
> >>> I read this in the H13 docs:
> >>>
> >>> Linear color workflow
> >>>
> >>>
> >>> Houdini is now set up to work in a linear color space/gamma of 2.2 by
> >> default.
> >>>
> >>> VEX texture functions that work on 8-bit images will now convert the
> >> images from sRGB colorspace to linear. You can override this with a
> >> variadic argument.
> >>>
> >>>
> >>> I am a little confused- isn't linear gamma '1.0'?...   Or is this
> saying
> >> that it is converting everything to 1.0 internally for calculations and
> >> then back to work properly with 2.2 screen gamma in GL Viewport and
> Render
> >> View?
> >>>
> >>> So should I leave my Render View at 2.2?  It seemed to look better at
> >> 1.0 for my PBR renders...
> >>>
> >>> Thanks,
> >>> Craig
> >>>
> >>> _______________________________________________
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> >>
> >>
> >>
> >> --
> >> Cheers,
> >>
> >> Peter B
> >>
> >> --No, I am not on Facebook.
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> >>
> >
> >
> >
> > --
> > .................................
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.................................
//sim+light+render
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