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News Valve adds asynchronous reprojection to SteamVR

Discussion in 'Article Discussion' started by Gareth Halfacree, 17 Nov 2016.

  1. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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  2. Stelph

    Stelph Member

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    Out of curiosity, what is the cheapest VR device that can be used with SteamVR currently? Is it still the Razer OSVR?

    http://www.razerzone.com/osvr
     
  3. Stanley Tweedle

    Stanley Tweedle NO VR NO PLAY

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    Valve Async is ok. It helps a little but nowhere near as good as ASW on Octopus.

    I own Vive and I've tried ASW on Octopus CV1. ASW wins.
     
  4. edzieba

    edzieba Virtual Realist

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    There is little technical detail on what Valve have implemented, but this section of the release notes:
    Indicates that their reprojection variant does NOT operate on every frame (as ATW does with Oculus' implementation) but only occurs reactively if a frame is missed. This is superior to their previous 'interleaved reprojection' mode (which would drop the render rate to 45FPS and would always have stutter from missing that first dropped frame), but does not have the total orientation motion-photons latency reduction of ATW, where EVERY frame has - for orientation - a motion-photons latency equivalent to the hardware scanout and display latency.
     
  5. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    I'm willing to be wrong, here, but isn't what you're describing asynchronous space warp, rather than asychronous time warp? Oculus had ATW, Valve worked on asynchronous reprojection as its own device-agnostic equivalent, then Oculus launched ASW which is superior to both ATW and Valve's AR. Presumably Valve is also working on its own version of ASW, which will bring it back to parity with Oculus - unless, of course, Oculus launches something else in the meantime.
     
  6. Stanley Tweedle

    Stanley Tweedle NO VR NO PLAY

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    Oculus will always be ahead on performance. Oculus runtime even without ASW or ATW is more efficient than steamvr.
     
  7. edzieba

    edzieba Virtual Realist

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    ATW: operates on every single frame immediately before display scanout*. Re-warps image based on orientation only. Completely independant of framerate, will always operate on the most recent frame no matter when it was rendered (could be 1ms old, could be several seconds if something freezes).
    ASW: When the render rate drops below a threshold (which is somewhere between 90FPS and 45FPS), ASW kicks in. Render rate is capped at 45FPS, and every other frame is synthesised using motion vectors and position tracking data from the two previous frames. After this frame is synthesised, it THEN passes through ATW like every other frame that is rendered.

    ASW is not a replacement for ATW, it operates alongside it.

    * On GearVR, ATW operates DURING scanout, 'racing the beam' by warping each line while the previous line is being read out.
     
  8. Gareth Halfacree

    Gareth Halfacree WIIGII! Staff Administrator Super Moderator Moderator

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    I sit corrected. Cheers for the knowledge-bomb!
     

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