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

[Matthew Heimlich]

All light sources should contribute to the shadow pass, environment lights
included. Some environments with HDRI cast a very distinct shadow. A shadow
catcher would indeed be the best option, though, as it could be given its
own pass without any additional issues.


On Sat, May 10, 2014 at 5:29 PM, Brecht Van Lommel <
brechtvanlommel at pandora.be> wrote:

> 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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>>
>>
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