[Bf-committers] Proposition: Multilayer EXR support

[Martin Poirier]

If I recall correctly, the direction is explicit in the definition of the layers in the EXR file. If other programs ignore this value, a bug should also be logged with them (it wouldn't be the first EXR bug at Adobe...).

Martin

--- On Fri, 1/29/10, Gustav Göransson <gustav.goransson at gmail.com> wrote:

> If both direction is allowed I think
> it could be wise to use the same
> direction as other common applications like Nuke, After
> Effects, Photoshop
> etc. which apparently uses the other direction. Or at least
> provide a "flip
> direction" option in the OpenEXR output panel.
> 
> /gustav
> 
> On Fri, Jan 29, 2010 at 16:25, Fabian Fricke <frigi.f at googlemail.com>
> wrote:
> 
> > I'm just thinking out loud here but it's vaguely the
> same topic:
> > I always wondered why the temp FSA samples are only
> being stored temporally
> > and not in coherence with the rendered frames, thus
> allowing compositing
> > after all frames were already renderd. Maybe as
> additional layers in the
> > same file, or in a folder alongside the frames.
> >
> > I don't know if there has been any discussion about
> this when the feature
> > was first introduced but I would think it's a
> desirable option.
> >
> > 2010/1/29 Ton Roosendaal <ton at blender.org>
> >
> > > Hi,
> > >
> > > It's not upside down, it's an accepted &
> documented option in exr that
> > > has issues... both directions are allowed, but
> when i worked on it
> > > there were weird things in the windows version of
> openexr or so... too
> > > long ago to recall. Investige this?
> > >
> > > -Ton-
> > >
> > >
> ------------------------------------------------------------------------
> > > Ton Roosendaal  Blender
> Foundation   ton at blender.org 
>   www.blender.org
> > > Blender Institute   Entrepotdok
> 57A  1018AD Amsterdam   The Netherlands
> > >
> > > On 29 Jan, 2010, at 15:34, Jeroen Bakker wrote:
> > >
> > > >  * Problem statement
> > > > Multilayer EXR files are used in 2 places.
> > > >
> > > > 1. to temporarily store the render buffers
> to reduce the memory
> > > > footprint between the render pass and the
> composition pass.
> > > > 2. to store the final output image as a
> multilayer exr.
> > > >
> > > > the problem is that multilayer exr's are
> stored upside down. For 1
> > > > it is
> > > > not a problem as the file is temporarily and
> used by blender renderer.
> > > > for 2: the output image makes the file's not
> easilly usable. You first
> > > > have to flip the image, before you can use
> it.
> > > >
> > > > * Expectation
> > > > the temporarily file must still be stored in
> the current form (upside
> > > > down) for performance reasons.
> > > > the output file must not be stored upside
> down, but still have all
> > > > render layers available. (open file with
> exrdisplay -C
> > > > RenderLayer.Combined.R filename.exr to see
> problem)
> > > >
> > > > Identifying the problem.
> > > > both accesses the same function in
> openexr_api.cpp and both are
> > > > triggered from the pipeline.c (blender
> renderer), but both have
> > > > different requirements:
> > > >
> > > > * Proposition/alternatives
> > > > there are several options how we can solve
> this:
> > > > 1. leave all the same, but just before
> writing the multilayer exr
> > > > output
> > > > image, flip all render buffers. The
> implementation of the multilayer
> > > > does not use the imbuf API, so will not
> effects other file formats and
> > > > is easilly doable
> > > > 2. update the imbuf api, to support
> multilayer images. more work, but
> > > > more futureproof to possible other
> (professional, non existing) output
> > > > formats
> > > > 3. use the exr tiles to save the image
> upside down (is something in
> > > > between solution 1 and 2)
> > > >
> > > > I would have chosen for option 1 as it is
> not that much work, and I
> > > > don't know what the requirements are for
> other professional output
> > > > formats. Solution 3
> > > >
> > > > Other issues in this area: the multilayer
> has is no default image/
> > > > layer;
> > > > all images are default black in other
> applications like nuke or
> > > > exrdisplay.
> > > >
> > > > What do you think what is the wise thing to
> do?
> > > > @Brecht, Campbell, is it OKE to patch
> pipeline as you are
> > > > restructuring
> > > > the renderer?
> > > >
> > > > Greetings,
> > > > Jeroen Bakker.
> > > >
> > > >
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