[Bf-committers] Multiview branch feedback

[Adriano Oliveira]

Hi Brecht,

> But can you explain to me specifically why that is better than the
workflow used in the branch?

Because it is more simple and better fits in actual Blender logic. It is
also the way everey other composite sistem works, as far as I know.


> But why? How is this different from the RenderLayer/RenderPass
distinction we have already?

The current SELECT VIEW approach in Image Editor is leading to limitations
and changing too much in Blender UI and Node Editor.

• Select View is not necessary because we already have Select Pass and L/R
views are simply new kind of passes.
• Select View "3-D" offers a fancy fast-composition that is independent
from Node Editor, so it turns Image Editor inconsistent with composition.
• Implementing Select View is a danger, because it changes a lot in Node
Editor output logic, without offering as much.
• Treating L/R as passes is just enough. We add new possibilities and don't
chage a lot what is already working.
• Obtaining Image Editor stereo outputs through composition nodes is just
enough and safer.
• To keep node editor compatible with new EXR capabilities we just need a
Nuke like merge channel node, so we can re-insert decomposed layers and
output them to a single file. This is useful beyond stereo.
• STEREO PREVIEW option in 3D View is ok. We don't need stereo options in
user preferences, as long as automated preview would only affect 3D View,
and Node Editor affects Image Editor.

Let's just not add to Node Editor/Image Editor  things that leads to
different and untested workflows that we don't miss.

This is a very nice discussion!

:D

Adriano




2013/6/17 Brecht Van Lommel <brechtvanlommel at pandora.be>

> Hi Adriano,
>
> On Mon, Jun 17, 2013 at 6:33 AM, Adriano Oliveira
> <adriano.ufrb at gmail.com> wrote:
> > Schneider's approach relies in Composite for obtain stereo results. This
> is
> > perfect for my outputs because it offers me control and uses what is
> right
> > there in Blender already. My stereo outputs are: (1) Side by site or over
> > under composites to preview in my 3d TV and web delivering; (2) separated
> > L/R files for blu-ray and DCP authoring.
>
> (2) works in the branch I think. (1) does not at the moment but would
> fit as a file save option.
>
> > Nevertheless, even with a good camera, sometimes we need to “lie” to get
> > good results. For example, to certain shot to work in stereo I may need
> to
> > control convergence of objects and background separately. Imagine a space
> > scene: camera close to an alien pilot in the cockpit, a second spaceship
> 10
> > meters way, and the star field in the background… No real camera rig
> would
> > get this right in one shot. We better control convergence plane by plane
> in
> > composite.
> >
> > Other example: take a real footage stereo shot, track it and try to place
> > 3d elements over it. Having access to R/L views from Render Layers is
> > essential for a good match.
>
> Ok, as far as I can tell all that fits in the current design.
>
> > When producing a stereo film, I miss these things:
> >
> > 1. A real stereo camera (or a good L/C/R camera rig) with numeric and
> > visual convergence/safe areas controls. Schneider's add-on is a good
> > starting point.
> > 2. OpenGL stereo preview of viewport, based on camera rig convergence. (I
> > think corrected color anaglyph or b/w anaglyph is the most useful here).
> > 3. Easy way to render L/R views with Cycles speed optimizations: not
> > calculating geometry twice, for instance.
> > 4. Easy way to access L/R views from Render Layers in Node Editor for me
> to
> > compose whatever I want. The Stereo Node that I proposed is not
> essential,
> > but something user-friendly as a ubbershader.
> > 5. EXR support for L/R views archiving, no doubt.
>
> 2,3,5 are implemented, 1,4 are planned I think. See here for the todo list:
> https://github.com/dfelinto/blender/issues
>
> > 1. Separate stereo preview in Blender's viewport (OpenGL / 3D View) from
> > render output in Image Editor. We don’t need automated multiview in Image
> > Editor, because the way it is done just masses with node editor/composite
> > output.
> > 2. Let me do my stereo composites in node editor. If you want to help
> > newcomers, create a Stereo Node, as I have proposed.
> > 3. I need to access views from a Render Layer the same way I have access
> to
> > render passes.
> > 4. Let us use the great work Dalai is doing with EXR 2 and go further by
> > adding ways to merge and insert new layers in composite output. This way
> we
> > could work views from Render Layers separately and recompose them to save
> > in EXR. The same functionalities would allow me to add/merge other new
> > layers (corrected mattes for instance) to composite output, so I can save
> > as EXR as well. This would be helpful for communicating with other
> > software, or among different teams.
>
> As far as I can tell, this all boils down to a different workflow than
> the branch has now. Instead of running the compositor once for each
> view, you want the compositor to run once and manually make a setup
> that applies nodes to both layers and merges them.
>
> But can you explain to me specifically why that is better than the
> workflow used in the branch? I understand it may be quite different
> than your current workflow and that it may be hard to transfer your
> existing nodes setups, but that doesn't make it invalid. I still don't
> see why you think it doesn't work, you can still do different things
> depending on the view with the Switch View node, you can compose a
> non-3D background, etc.
>
> Even then, you could create a separate scene to do compositing of both
> views in a single node setup at the same time, once the Render Layer
> node has a view option?
>
> > 5. We don’t need a SELECT VIEW in Image Editor, just the list of the true
> > layers in the image. No matter it may seams repetitive, it is just more
> > correct and informative. In addition, if we implement a node do add/merge
> > new layers in the composition, we will need to see them listed in Image
> > Editor's SELECT PASS.
>
> But why? How is this different from the RenderLayer/RenderPass
> distinction we have already?
>
> > Small points:
> >
> > 6. Let’s change any reference to "3-D" to "Stereo" or "Multiview".
> > 7. I would prefer not create a new Render Views tab in Properties panel.
> > It's functions may better be relocated to recently created Render Passes
> > tab.
>
> 6 seems reasonable, 7 is planned.
>
> Brecht.
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