[Bf-cycles] Disney BRDF Implementation in Cycles
Zauber Paracelsus
zauber at gridmail.org
Wed May 11 19:39:59 CEST 2016
Pardon my asking, but what is clearcloat? Is that a simulation of
having a thin layer of glossy/transmissive material on top of another?
(eg: simulating things like varnish)
On 05/11/2016 01:36 PM, "Pascal Schön" wrote:
> Thanks for your quick replies.
>
> Some words to the implementation:
>
> I've already splitted the BRDF into three closures after trying to get
> a single closure implementation to work correctly. But it came to my
> mind that this would be against the cycles architecture of splitting
> stuff into diffuse and glossy. And it made it also much more complex.
>
> The three closures are:
> - disney_diffuse(...): Calculates the Burley diffuse term, subsurface
> scattering and the sheen
> - disney_specular(...): Calculates the "normal" specular highlight and
> the metalness (also anisotropy is included here)
> - disney_clearcoar(...): By this the clearcoat specular highlight is
> calculated (less bright and no anisotropy)
>
> In an OSL script, which is also the script for the node, these three
> closures are called correctly and added together.
>
> I've already seen the updated version of the Disney BRDF but I wanted
> to focus on the more simple one that was proposed in 2012. The
> additionals (like getting from a BRDF to a BSDF) would be one of the
> next steps.
>
> I'm going to commit my implementation to a new branch next week,
> because this week is a bit stressful and as it is my first commit, I
> wanted to take some time for it.
>
> Pascal
> On 11.05.16, 19:06 Stefan Werner <swerner at smithmicro.com> wrote:
>
> Eventually, it might be interesting to split it into separate
> closures, so that one can still use separate ray counts for
> specular/diffuse/transmission and get them to render into separate
> passes. This will probably require to put fresnel back into the
> closures (going back in history, it looks like Cycles initially
> had that).
>
> Stefan Werner | Senior Software Engineer; Productivity & Graphics
> Smith Micro Software, Inc. |http://www.smithmicro.com
> <http://www.smithmicro.com> <http://www.smithmicro.com/>
>
>
>
>
>
> On 5/11/16, 4:18 PM, "bf-cycles-bounces at blender.org on behalf of
> Lukas Stockner" <bf-cycles-bounces at blender.org on behalf of
> lukas.stockner at freenet.de> wrote:
>
> >Hi!
> >
> >The Disney BRDF shader is actually pretty interesting for Cycles!
> >I've played around with it for a while as well, but my code isn't
> fully
> >working yet, so it'd be awesome to have your code around.
> >
> >Some notes:
> >- There's actually a later revision of the paper you linked with
> a few
> >more details, might be handy:
> >https://disney-animation.s3.amazonaws.com/uploads/production/publication_asset/48/asset/s2012_pbs_disney_brdf_notes_v3.pdf
> >- There's also a completely revised BSDF that includes actual
> subsurface
> >scattering and transmission, and they note that it solves a few
> issues
> >with energy conservation and path tracing in general that the
> original
> >2012 BRDF has:
> >http://blog.selfshadow.com/publications/s2015-shading-course/burley/s2015_pbs_disney_bsdf_notes.pdf
> >- I'm currently working on energy-conserving microfacet closures,
> which
> >would pretty much solve the issue that caused them to include the
> sheen
> >stuff - at the cost of not being 100% compatible to other
> implementations.
> >
> >But that can all be handled later - in general, it would be
> awesome to
> >have the Disney BRDF/BSDF in Cycles, and your code would certainly be
> >welcome! Even if we go with the revised BSDF, it is pretty similar to
> >the original BRDF, so it could be upgraded easily.
> >
> >Lukas
> >
> >
> >Am 11.05.2016 um 15:57 schrieb "Pascal Schön":
> >> Hey guys,
> >>
> >> For a few months now I’m implementing (on a private repository) the
> >> Disney BRDF shader
> >>
> (https://disney-animation.s3.amazonaws.com/library/s2012_pbs_disney_brdf_notes_v2.pdf)
> >> as a new node in Cycles. By now there have only been a few external
> >> approaches, where a render server (like in Appleseed or
> Renderman) is
> >> accessed by a Blender plugin. But it would be nice to get
> access to this
> >> without any additional software to install.
> >>
> >> The current state of my implementation is, that the OSL closure is
> >> finished and has also been tested against Renderman. Both acted
> the same
> >> in my testcases (except for the rendering approches by the two
> >> renderers, which cause some minor differences in indirect
> lighting).
> >> Another step that I’ve taken was to implement the node to
> easily access
> >> the Disney BRDF.
> >>
> >> Currently OSL has to be activated, because I haven’t done all
> steps to
> >> include the Disney BRDF completely in Cycles. But I think
> that’s only
> >> one small step to take. There I hope to get some help by the
> community
> >> because it's a bit confusing where to add which code fragment.
> >>
> >> You can see some screenshots here:
> >>https://www.dropbox.com/sh/j7w4v0bu9a5jhvz/AADSF3nm3LZCZnHgyPMwhrT6a?dl=0
> >>
> >> I would be pleased if you tell me if this would be nice to have
> or if it
> >> is too special for Blender.
> >>
> >> Pascal
> >>
> >>
> >>
> >>
> >>
> >>
> >>
> >> _______________________________________________
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> >> Bf-cycles at blender.org
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> <https://lists.blender.org/mailman/listinfo/bf-cycles>
> >>
> >
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