[Bf-cycles] Motion Blur Implementation

[Nate Wiebe]

Not entirely related, but will the scope of this GSOC cover curved motion
blur?

-NateW


On Mon, Jun 10, 2013 at 11:29 AM, Brecht Van Lommel <
brechtvanlommel at pandora.be> wrote:

> Yes Blender supports this, it does scene.frame_set(frame, 0.0) now,
> the second value is a subframe value between 0.0 and 1.0.
>
> On Mon, Jun 10, 2013 at 4:58 PM, Gavin Howard <gavin.d.howard at gmail.com>
> wrote:
> >      Hello,
> >
> >      Does Blender allow exporting at arbitrary subframes? If not, that
> might
> > be a problem. If so, then Stuart has me exploring the code, and I think
> that
> > I could write the patch while doing so. Does that sound okay?
> >
> >      God Bless,
> >      Gavin Howard
> >
> > On Jun 9, 2013 6:34 AM, "Brecht Van Lommel" <brechtvanlommel at pandora.be>
> > wrote:
> >>
> >> We should support exporting at the exact shutter time. At the time I
> >> implemented motion blur evaluation at subframes was actually broken
> >> for shape keys and physics systems so I didn't use it, but that has
> >> been fixed since.
> >>
> >> However, exporting motion from the frame positions may be useful to
> >> keep as it may give more predictable results in some cases. When
> >> you're editing animations that's the only thing you actually see in
> >> animation playback, so the motion between those frames may contain
> >> some unexpected things that you don't want to render.
> >>
> >> I don't know how common that is, did not look at .blend files yet to
> >> see how different the results are, if it is an issue we should
> >> probably have an option (off by default) to only export motion from
> >> integer frame numbers and no subframes.
> >>
> >> On Sat, Jun 8, 2013 at 7:36 PM, Gavin Howard <gavin.d.howard at gmail.com>
> >> wrote:
> >> >      Hello all,
> >> >
> >> >      I have a question about implementation. I have been told by
> >> > Brecht that currently, the Cycles addon exports three steps for motion
> >> > blur to the renderer: one at the previous frame, one at the current
> >> > frame, and one at the next frame.
> >> >
> >> >      Now, my memory may not be serving me well here, so I may have
> >> > gotten the details wrong. But if not, shouldn't the addon actually use
> >> > the shutter time to determine the first and third steps? For example,
> >> > shouldn't the addon export a step at the start of the shutter time,
> >> > one at the current frame, and one at the end of the shutter time?
> >> > Also, I think this type of reasoning should apply even when multi-step
> >> > (more than 3) motion blur is added. (Multi-step blur is needed for my
> >> > Deformation Motion Blur GSoC project, so I will add it over the
> >> > summer.)
> >> >
> >> >      In short, I think that the shutter time should be the goto for
> >> > exporting motion blur steps. If it is, then just ignore this. But if
> >> > it's not, should we change it? Anyway, that's my two cents.
> >> >
> >> >      God Bless,
> >> >      Gavin Howard
> >> > _______________________________________________
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> >> > Bf-cycles at blender.org
> >> > http://lists.blender.org/mailman/listinfo/bf-cycles
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> >
> >
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