[Bf-cycles] Shadow Pass including IBL + mesh Lights (VFX)

[Brecht Van Lommel]

The mesh lights choice was a bit arbitrary and could be changed. For the
environment light, if we included that in the current shadow pass you would
basically get ambient occlusion, which is not so useful because you have
that already in a pass.

The shadow pass could be changed to handle this case better, which would be
roughly the same as implementing a shadow catcher material.

Brecht.
On May 10, 2014 8:57 PM, "Greg Zaal" <gregzzmail at gmail.com> wrote:

> If I understand Thomas correctly, he's simply asking if we can have mesh
> lights contribute to the shadow pass, and perhaps environment lighting as
> well if possible.
>
> Was it a design choice not to have mesh lights included in the shadow
> pass? If so, why? Just a performance issue, or is it somehow useful not to
> have them? I don't have much experience in compositing renders with GI, so
> forgive my ignorance if the answer is obvious.
>
> Cheers,
> Greg
>
>
> On 10 May 2014 00:27, Brecht Van Lommel <brechtvanlommel at pandora.be>wrote:
>
>> In V-Ray or Mental Ray, is really all you use the shadow pass to get
>> this working with IBL? Or do you also use "shadow catcher" or "shadow
>> matte" materials? To me it seems what you are really asking for is the
>> latter, but maybe I misunderstand how this works.
>>
>> You can emulate shadow catchers using render layers, but the render
>> time is longer than it would be if it was done natively:
>> http://www.pasteall.org/blend/29068
>>
>> It's unlikely that I will work on a shadow catcher material in the
>> next months, if someone wants to work on that I can help them, but I
>> have other priorities at the moment.
>>
>> Brecht.
>>
>> On Fri, May 9, 2014 at 9:44 PM, Thomas Beck <software at plasmasolutions.de>
>> wrote:
>> > Hi Brecht,
>> >
>> > as we are creating a lot VFX for the advertising industry and we're
>> > converting our projects slowly but steadily to Cycles we're now at a
>> point
>> > that bothers me and my colleagues a lot: A proper shadow pass that
>> includes
>> > HDR environment lights and mesh lights.
>> >
>> > In our production work flow we're taking light probes on the set
>> whenever we
>> > need to create cg elements afterwards, this way we match the lighting
>> > situation perfectly with the real world conditions.
>> > When we compose those elements into the shot we're used to use the
>> shadow (&
>> > AO) pass (in vray / mental ray) and were a bit surprised as we saw that
>> > we've got no possibility to mimic that behaviour with Cycles and our
>> > lighting requirements as mesh and environment lights are not considered
>> in
>> > cycles shadow pass..
>> >
>> > Today I asked DingTo on IRC and he told me that there is a way to take
>> mesh
>> > lights into account by deleting "ls.prim == PRIM_NONE && " in
>> > kernel_emission.h
>> > That is already a big leap forward but does not help us on our light
>> probe
>> > (IBL) work flow...so the question is: Do you know that this is not only
>> a
>> > small missing feature but is really crucial for VFX work? I talked with
>> > Sebastian too and he's also missing it very much - without this, many
>> > projects are very cumbersome to do atm.
>> >
>> > I searched a bit and was led to the wiki page where you collect all
>> todos
>> > and especially this:
>> >
>> > Option to include environment lighting in shadow pass.
>> >
>> > http://wiki.blender.org/index.php/Dev:2.6/Source/Render/Cycles/ToDo
>> >
>> > I really don't want to bash here - just raise the awareness of this
>> issue.
>> > It's not only a missing feature, it's really a show stopper for us.
>> >
>> > Is that feature hard to implement? Is there any chance you could tackle
>> this
>> > issue in a relatively short amount of time? Should I write Ton and beg
>> for
>> > dev time?
>> >
>> > If you'd like to talk just drop me a message @plasmasolutions or g+ and
>> I'll
>> > be online in IRC...
>> >
>> > Many greetings, Thomas
>> >
>> > P.S: I'm happy that I'm not the only one with this request but I still
>> > wonder why there are not many more? Is Blender rarely used in the VFX
>> field?
>> > https://developer.blender.org/T34272
>> >
>> > --
>> >
>> > ------
>> > Plasmasolutions
>> > Design | Development | Training
>> >
>> > Website: Http://www.plasmasolutions.de
>> > Blog: Http://blog.plasmasolutions.de
>> >
>> >
>> > _______________________________________________
>> > Bf-cycles mailing list
>> > Bf-cycles at blender.org
>> > http://lists.blender.org/mailman/listinfo/bf-cycles
>> >
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