[Bf-cycles] No Caustics Feature

[Przemyslaw Golab]

I actually made some tests and Filter Glossy is much better
choice than diffuse trick, at least for some scene/purposes.

Filter Glossy produced less noise and it didn't introduced
some additional indirect lighting, like diffuse would.
It looks more like rough glossy indir than diffuse indir,
which in most cases would be preferable I guess.

Diffuse indir introduces more light form sides when filter glossy indir
gives more directional reflection of light:

http://i.imagebanana.com/img/e30odrz7/Selection_073.jpg

but Sebastian's shader would be very useful when option
"No Caustics" needs to be turn ON.


2013/1/15 Brecht Van Lommel <brechtvanlommel at pandora.be>

> On Tue, Jan 15, 2013 at 4:10 PM, Nate Wiebe <natewiebe13 at gmail.com> wrote:
> > After watching this video by Sebastian (http://youtu.be/4-yCJlcXjOg),
> I'm
> > wondering if it's possible to have this happen in the background
> > automatically when enabling 'No Caustics'.
> >
> > It seems to me that the purpose of No Caustics isn't to remove GI or
> bounce
> > lighting. It would be a pain to have to manage two sets of materials if
> you
> > want to render a scene sometimes with and sometimes without caustics
> during
> > an animation.
>
> The option No Caustics should keep doing what it does, similar to
> other render engines were you can also just disable caustics without
> the render engine trying to add in a replacement. It is the intention
> of this option to remove a light path.
>
> > If it doesn't become the default action, it would be great to have an
> option
> > somewhere to make this happen without having to change the materials. It
> > greatly improves the scene without adding in the overhead of caustics.
> >
> > If there is a reason this could not work properly, I'd like to hear.
>
> Well, the Filter Glossy option is intended exactly for this, however
> perhaps it's not working as well as it could. Currently higher values
> here will increase the roughness in Glossy BSDF's, but more roughness
> doesn't quite make it diffuse, and diffuse tends to give less noise.
> Perhaps we should improve this option so that the surfaces gradually
> become diffuse. In fact for some BSDF's this would happen
> automatically but it's not the case for the ones we implement.
>
> Also, the trick in the video works ok for the diffuse-glossy case but
> it only solves part of the problem. A rough glossy reflection followed
> by a sharp glossy relection will still show the same noise, the Filter
> Glossy option was intended to handle both cases. So I think it would
> be better to look into improvements there.
>
> Brecht.
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