[Bf-vfx] Footage for Tracking
Keir Mierle
mierle at gmail.com
Wed Jun 8 20:53:50 CEST 2011
On Wed, Jun 8, 2011 at 11:50 AM, ibkanat <ibkanat at gmail.com> wrote:
> Didnt Julian or someone add a fix to rolling shutter to libmv recently?
>
No, there is no rolling shutter support.
> I also found a interesting paper that was in siggraph two years
> ago(http://pages.cs.wisc.edu/~fliu/project/3dstab.htm)
>
Yes, this is extremely cool, but doesn't deal with rolling shutter. Once we
have tracking basics in place, we could do this; it's not too difficult.
Keir
>
> On Wed, 2011-06-08 at 11:32 -0700, Keir Mierle wrote:
> > Thanks Colin!
> >
> >
> > One point though: RED uses a CMOS sensor and is subject to rolling
> > shutter. Do you know how bad it is? Some cameras have very slow sensor
> > readout (and so terrible distortions with movement) and others have a
> > faster rolling shutter which still has distortions, but less.
> >
> >
> > For those who don't know: rolling shutter means that each scanline has
> > a *different* shutter time! Yes, that means that the image is composed
> > of 1000's of images, one scanline taken from each, with the camera
> > moved between images. Extremely annoying, and totally breaks all the
> > camera tracking assumptions.
> >
> >
> > I realize that we have to handle rolling shutter but it's a big job
> > and we won't support it in the first release.
> >
> >
> > So I repeat my request: does anyone have a camera that doesn't have a
> > rolling shutter? For example, the Panasonic SD9 has a CCD sensor and
> > so takes true pinhole images for each frame.
> >
> >
> > Virtually all modern DSLR's have awful rolling shutter (D90 included),
> > so they are also excluded.
> >
> >
> > Keir
> >
> > On Wed, Jun 8, 2011 at 11:00 AM, Colin Levy
> > <colin at peerlessproductions.com> wrote:
> > Hey guys,
> >
> >
> > I've got several TB worth of 4K material I can offer for
> > tracking. However, the shots will represent a more
> > "real-world" scenario rather than the test case shots listed
> > below.
> >
> >
> > I don't suppose you want the RED .r3d files, so will TIFF
> > sequences work for you? (Or do you want both?) I will go
> > through my drives in the next few days and upload a few shots
> > to my FTP, if you think this would be useful! Let me know
> > whether you'd like 32-bit images, with all the 'RAW' data
> > intact, or if 8 or 16bit will suffice.
> >
> >
> > One thing to note regarding resolution: I have noticed that in
> > many cases, tracking downrezzed shots is frequently more
> > successful than trying to track the raw 4K material. This may
> > have something to do with the default values (the default auto
> > feature search range, for example, may be something like 20px
> > rather than 80px, which might be a better setting for 4K).
> > For my projects I usually downrez to 2K before tracking...
> > also because it's a lot faster. :P
> >
> >
> > Great discussion. Can't wait to see these tools develop!
> >
> >
> > --Colin
> >
> >
> >
> >
> >
> > On Jun 8, 2011, at 12:59 PM, François T. wrote:
> >
> > > I'll do all that on saturday with D90.
> > >
> > >
> > > cheers
> > > F.
> > >
> > > 2011/6/8 Keir Mierle <mierle at gmail.com>
> > > A catalog of the following shots would be useful:
> > > * General motion: Moving and rotating camera.
> > > Camera is /not/ always pointing at one part
> > > of the scene.
> > > * Rotation only: camera on a tripod, rotating
> > > around a fixed point (if possible the
> > > camera's "Nodal point", but you need a
> > > special tripod for that)
> > > * Translation only: walking sideways keeping
> > > the camera pointed forward (e.g. not
> > > circling)
> > > * Translation only: walking towards the scene
> > > * General motion when the scene is planar
> > > (e.g. camera keeps a big billboard in view
> > > and only the billboard)
> > > * Circle strafing around an object; camera is
> > > fixated on one part of the scene
> > > (intersecting principal ray)
> > > The scenes should have good texture so that tracking
> > > is easy; we can add challenging scenes later. It's
> > > ok if the translation-only scenes have some hand
> > > held wobble; that's fine. Boxes with texture are
> > > good. Complicated objects like bushes or trees are
> > > bad. The scene must be static (no cars, people,
> > > birds, godzilla, etc).
> > >
> > >
> > > The camera must be calibrated. There is a libmv
> > > calibration target that you can affix to a really
> > > flat object. The calibration target must be really
> > > flat; something that has a bit of bend is
> > > unacceptable and will give poor results.
> > >
> > >
> > >
> http://libmv.googlecode.com/svn/trunk/extras/calibration/calibration.pdf
> > >
> > >
> > > Take several images of the calibration target (or a
> > > video in HD). Get different rotations and fill the
> > > frame to get the edges (important for distortion
> > > correction). Then run one of the calibration tools
> > > to find the intrinsic parameters (focal length in
> > > pixels, distortion, skew, etc).
> > >
> > >
> > > Note: Rolling shutter is *horrible* for tracking.
> > > We're going to have to handle it at some point, but
> > > I am trying to avoid it as long as possible. Do you
> > > have access to a CCD style camera without a rolling
> > > shutter?
> > >
> > >
> > > Keir
> > >
> > >
> > > On Tue, Jun 7, 2011 at 3:27 PM, Ian Hubert
> > > <ian at projectlondonmovie.com> wrote:
> > >
> > >
> > > Hey all!
> > >
> > >
> > > I've been following the conversations, and
> > > wanted to throw out that if anyone needs any
> > > sort of footage, I can run out and film
> > > stuff. I already have a few things things
> > > filmed- mostly just walking around the city
> > > holding the camera as steady as I can- but
> > > if anyone wants anything else (underexposed,
> > > really shaky, steady smooth,
> > > panning--but-no-movement, somebody walking
> > > across the frame, stuff like that), just say
> > > so!
> > >
> > >
> > > At this point all I can quickly provide is
> > > SD and HD- I unfortunately don't have access
> > > to a 4k camera, but I'll film some random
> > > stuff if I ever get my hands on one.
> > >
> > > --
> > > Ian Hubert
> > >
> > >
> > >
> > > _______________________________________________
> > > Bf-vfx mailing list
> > > Bf-vfx at blender.org
> > >
> http://lists.blender.org/mailman/listinfo/bf-vfx
> > >
> > >
> > >
> > >
> > > _______________________________________________
> > > Bf-vfx mailing list
> > > Bf-vfx at blender.org
> > > http://lists.blender.org/mailman/listinfo/bf-vfx
> > >
> > >
> > >
> > >
> > > --
> > > ____________________
> > > François Tarlier
> > > www.francois-tarlier.com
> > > www.linkedin.com/in/francoistarlier
> > >
> > > _______________________________________________
> > > Bf-vfx mailing list
> > > Bf-vfx at blender.org
> > > http://lists.blender.org/mailman/listinfo/bf-vfx
> >
> >
> >
> > _______________________________________________
> > Bf-vfx mailing list
> > Bf-vfx at blender.org
> > http://lists.blender.org/mailman/listinfo/bf-vfx
> >
> >
> >
> > _______________________________________________
> > Bf-vfx mailing list
> > Bf-vfx at blender.org
> > http://lists.blender.org/mailman/listinfo/bf-vfx
>
>
> _______________________________________________
> Bf-vfx mailing list
> Bf-vfx at blender.org
> http://lists.blender.org/mailman/listinfo/bf-vfx
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.blender.org/pipermail/bf-vfx/attachments/20110608/48d2bbb3/attachment.htm
More information about the Bf-vfx
mailing list