[Bf-vfx] Footage for Tracking

Thu Jun 9 19:40:21 CEST 2011

with a client on 16bit DPX where the footage was very dark and bright as
very small part in the image. That did help a lot yes, but I can't share the
footages.
I know in Syntheyes, you have to specify, how you want to import the
footages 8bits or 16bits (or higher, can't remember). I usually work with
8bits anyway, but I know that in that special case it helped me a lot. Also
when you are doing pre-processing 16bit is better, but that will be done by
Blender, so I don't think you care to much about this part.
I'm not sure how syntheyes is dealing with bpc with the trackers though. I
just know it does make a difference.

2011/6/8 Keir Mierle <mierle at gmail.com>

> On Wed, Jun 8, 2011 at 1:44 PM, François T. <francoistarlier at gmail.com>wrote:
>
>>  Regarding file formats: JPEG frames are probably fine; there's little
>>> value in tracking on 16-bit data. The frames can even get converted to
>>> grayscale, since the tracking ignores color information.
>>
>>
>> are you not planning on using all the depth on the image for tracking ? in
>> my experience, it can helps a lot sometimes !
>
>
> Maybe eventually but not to start. Libmv takes 32 bit grayscale float
> images to track them. However, I'm skeptical that more than 8 bits of
> grayscale data would make a difference for tracking. Do you have examples
> where this is the case?
>
> Keir
>
>
>> 2011/6/8 Keir Mierle <mierle at gmail.com>
>>
>>> On Wed, Jun 8, 2011 at 11:53 AM, Colin Levy <
>>> colin at peerlessproductions.com> wrote:
>>>
>>>> Yeah, rolling shutter is an *incredible* pain.  It can be corrected to
>>>> an extent with tools like The Foundry's "RollingShutter" plugin for Nuke,
>>>> which I've heard can make previously un-trackable shots trackable, but you
>>>> see it *everywhere* these days -- even in hollywood features.
>>>>
>>>
>>> Yes, we will deal with it but it will take some time. It's mathematically
>>> impossible to fix perfectly, so the best we can do is approximate fixes.
>>> Truly unfortunate.
>>>
>>>
>>>> I do have some footage I can get you from my Canon XH-A1, which is a
>>>> 3-CCD HDV camera.  I sold the camera recently (CMOS is all the rage!), but I
>>>> have a ton of footage I can go through.
>>>>
>>>
>>> That would be great! The only constraint is going to be calibration. Can
>>> you get access to the camera for 10 minutes to take some shots of a
>>> calibration pattern?
>>>
>>> I realize the big tools deal with this automatically, but it's difficult
>>> to do automatically and won't be supported in our first release.
>>>
>>>
>>>> That said, RED's CMOS sensor is waayy better than the "jellocam" sensors
>>>> in DSLRs like the 5D or T2i.  (RED's new MX sensor I think is even better).
>>>>  So the rolling shutter is not bad -- but it's still noticeable in very
>>>> high-motion shots.
>>>>
>>>> I'd say 80% of the RED shots I've got should not pose issues due to
>>>> rolling shutter.  The tracking tools I've been using do not account for
>>>> rolling shutter, yet I'm able to get very solid tracks with little manual
>>>> intervention.  So perhaps still valuable to test with?
>>>>
>>>
>>> Sounds like the RED shots will work as long as the motion is not too
>>> extreme.
>>>
>>> Regarding file formats: JPEG frames are probably fine; there's little
>>> value in tracking on 16-bit data. The frames can even get converted to
>>> grayscale, since the tracking ignores color information.
>>>
>>> Keir
>>>
>>>
>>>> --Colin
>>>>
>>>>
>>>> On Jun 8, 2011, at 2:32 PM, 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
>>>>>>>
>>>>>>> _______________________________________________
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>>>>>>>
>>>>>>>
>>>>>>
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>>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> ____________________
>>>>> François Tarlier
>>>>> www.francois-tarlier.com
>>>>> www.linkedin.com/in/francoistarlier
>>>>>  _______________________________________________
>>>>> Bf-vfx mailing list
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>>>>>
>>>>>
>>>>>
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>>>>>
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>>
>>
>> --
>> ____________________
>> François Tarlier
>> www.francois-tarlier.com
>> www.linkedin.com/in/francoistarlier
>>
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-- 
____________________
François Tarlier
www.francois-tarlier.com
www.linkedin.com/in/francoistarlier
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