Do you believe the 120 fps version of Ang Lee's film really uses a 216 degree virtual shutter?

Discussion in 'General Chat' started by 200p, Sep 19, 2016.

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  1. 200p

    200p
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    Do you believe the 120 fps version of Ang Lee's film really uses a 216 degree virtual shutter?

    Some sites are saying Ang Lee's film, Billy Lynn's Long Halftime walk (which was captured with a 360 degree/open shutter) uses a 216 degree virtual square shutter for the 120 fps version of the film.
    eg. Ang Lee Shows the Future of Cinema Display (Updated)
    I can see how it would easily work and be true for the 24 fps version to have a 216 degree shutter (since each "open shutter" frame of the original 120 fps recording=one 72 degree 'slice' of a 24 fps version (120/24=5. 360 degrees/5=72 degrees). So 3 original frames from the original 120 fps version blended=one 216 degree frame for the 24 fps version).

    Also note that "TruMotion" in the article above is spelt wrong and it's (RealD's) "True Motion".

    On the RealD site, which gives some explanation of how it's True Motion works, nowhere does it mention that 'True Motion' uses any motion interpolation/motion compensation. True Motion just seems to work using ways already likely being done by others (eg. Pickfair institute/Douglas Trumbull), ie. combining frames from a high fps source (eg 120 fps) and allowing a certain weighting to each frame (eg. for a lower fps version).

    So surely it's the lower fps versions of the film that may use a 216 degree virtual shutter (eg. the 24 fps version should be able to use it quite accurately), not the 120 fps version?
     
    Last edited: Sep 19, 2016
  2. jaguar180180

    jaguar180180
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    I'm so out of date with what's what these days I can't even understand the question never mind answer it.
     
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  3. 200p

    200p
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    Here's RealD site which explains how their "True Motion" works:
    RealD - Visual Technology

    Also, RealD aquired it from Tessive, and Tessive's site has demos too.
    Home
     
  4. DarenD

    DarenD
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    Sorry I'm an engineer and I have no clue about what your asking aswell.

    Would it not be best to ask the same question if a different part of the forum more tailored to films?
     
  5. Kieron

    Kieron
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    Yes.
     
  6. 200p

    200p
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    Then how do you think Reald is creating the 216 degree frames (accurate ones) for the 120 fps version from 120 fps 360 degree source frames?
     
    Last edited: Sep 19, 2016
  7. Kieron

    Kieron
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    Magic?
     
  8. EarthRod

    EarthRod
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    That would be virtual magic because the virtual shutter seems to be of some virtual importance. In addition, the virtual shutter is divided up to reduce virtual flicker and strobe on the virtual shutter.

    It is magic though because the 360 degree shutters in the cameras capture everything, however it is said this new technology still needs some work and understanding.

    ...With emphasis on understanding.
     
  9. 200p

    200p
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    Here's a video to help with the understanding - of the non-magic part (previously in another thread):
    Showscan Digital from Douglas Trumbull

    In the video above, first (around 1:07), Mr. Trumbull says "when you shoot a movie at 24 fps, half the time the shutter is closed and half the time the shutter's open" (basically describing the normally used 180 degree shutter).

    Around 1:50, he says (For 120 fps to 24 fps) "we can combine 3 frames into one and delete the next two to get 24 fps". He's then says (looking at the frames on screen) how shooting at 120 fps and converting down looks "exactly" the same as shooting normally at 24 fps (ie. with a 180 degree shutter), when:
    1) The images on screen don't look identical
    2) combining 3 frames into 1 and deleting the next 2 isn't giving you a (virtual) 180 degree shutter - because the shutter isn't open half the time (as a "180 degree" shutter is).
    3) Combining 3 frames (from the original 120 fps 360 degree source frames) into 1 (for the 24 fps version) is actually giving you 216 degree shutter (as described in the first post). Though you can't get exactly 180 degrees for the 24 fps version from a 120 fps 360 degree (open shutter) source - the closest you can have (because you can only use a 72 degree multiple - see first post) is either 36 degrees less (144 degrees) or 36 degrees more (216 degrees - what is shown in Mr. Trumbull's video and what Ang Lee seems to have used).

    But the above doesn't say how they can get a 216 degree 120 fps version from the 120 fps 360 degree (open shutter) source video (that various sites have claimed Ang Lee said is used - see link in first post).
     
    Last edited: Sep 20, 2016
  10. Tempest

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    Knew nothing about this but have a question.

    Ok, so I get the 24 frames a sec with the shutter closed half the time is bad, no one can question that.

    So, shoot at 120 frames per second. Yes, brilliant, again I'm sure everyone can understand how that would be far far better, capture much finer video, less blur etc etc etc....

    What I don't get is, once you have done that, why then chop/delete/merge the 120 capture back down to a crappy 24.

    Why not just project the movie back to the audience at the originally shot 120 fps?

    If this being done just because current projectors cannot cope with running at 120 fps, or because of the amount of storage/data having 120 fps fully would mean?
     
  11. 200p

    200p
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    Ang Lee's team, after showing a presentation of footage from the film in 4K, 3D, 120 fps format said, when asked how many theatres could (currently) show it in that format said "zero". So it's the projector(s) installed currently that can't handle the full format (4K, 3D, 120 fps).

    The footage showing converting down was from Douglas Trumbull and it showed examples of how it could be (not totally accurately) converted to 24 fps or 60 fps (60 conversion can be more accurate). But conversions won't just be needed for cinema showings, but for TV/home media (eg. UHD Blu-ray can only do 60 fps. TV can't show 120 fps sources yet (other than in demos by LG etc. and it's not in a currently used broadcast format).

    Here's Ang Lee and teams presentation where they answer a question asking about how many theatres can show it in the format they saw it in:
    Ang Lee - Pushing the Limits of Cinema - Full...


    See 1:03:24 in the video above. Some one asks about how many theatres can currently show it in the format shown. They say "zero", then explain what various projectors can use, eg. 120 fps 2K 2D, or 60 fps 2K 3D, and that roughly 2/3rds of the installed based are capable of that. He also said with dual projectors (installations) they could run 120 fps 2K 3D. That's what he said. I'm not sure whether or not DCI (Digital Cinema Initiative?) specs might limit it further - if they chose to release it to normal DCI standards.

    What they doing really is pushing the standards - if no one shoots in formats higher than the various specs currently allow (cinema projectors/DCI standards/TV/TV broadcast/home media standards), then the various companies will have less reason to update the standards. So they're encouraging the cinema/DCI and other standards to be updated by using formats that have never been used (at least for full length theatrical films) before.
     
    Last edited: Sep 20, 2016

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