Pen latency test

Discussion in 'Hardware' started by surfaceproartist, Nov 4, 2016.

  1. surfaceproartist

    surfaceproartist Scribbler - Standard Member Senior Member

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    This morning, a Twitter follower asked me about pen latency on the Surface Studio and another artist chimed in that latency was unacceptable on the Microsoft devices.

    I went down to the store and shot a quick 200 fps test in Sketchable and then came home and reproduced it on the Cintiq Companion and again in Procreate on the iPad Pro.

    This image is a 1/200 time slice (5 milliseconds), shot mid-stroke. Latency is virtually identical between all three devices and pen technologies, roughly 100 milliseconds (20 frames).

    [​IMG]

    Any comments on my methodology? Did I get the math right?
     
  2. Marty

    Marty Scribbler - Standard Member Senior Member

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    In my post about Microsoft's research into pen latency, I posted both a video and picture showing the measurement of pen latency (@19:00):



    [​IMG]

    Latency is properly measured as the time it takes between moving your pen on the screen and when the stroke updates to the tip position on screen.

    To measure this fairly, you would need draw at the same speed on all three machines, then count the number of frames it takes for the line on screen to 'catch up' to the tip.
     
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  3. surfaceproartist

    surfaceproartist Scribbler - Standard Member Senior Member

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    Yep. That's what I did. That's how I come up with 100 milliseconds, give or take.
     
  4. Marty

    Marty Scribbler - Standard Member Senior Member

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    In the MS presentations they suggested current pen latencies generally fall around 100ms in most apps, but under Windows 10 DirectInk (eg. Sketchpad) should have been reduced by almost half (at least for N-Trig).

    Do you observe this reduction?
     
  5. surfaceproartist

    surfaceproartist Scribbler - Standard Member Senior Member

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    I only tested with Sketchable, which I assume uses DirectInk, and I still get 100ms.
     
  6. Azzart

    Azzart Late night illustrator Senior Member

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    It should be interesting to see how clip studio and photoshop fare on the Studio in this regard.
    I imagine clip studio will act better.
     
  7. surfaceproartist

    surfaceproartist Scribbler - Standard Member Senior Member

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    I think a lot of the perception of Surface pen lag comes from Photoshop's overall sluggishness. Maybe it just runs better in OSX?
     
  8. Azzart

    Azzart Late night illustrator Senior Member

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    Blasphemy!

    :D
     
  9. ATIVQ

    ATIVQ Vā…Oā…„ Senior Member

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    You took the shots at a bad moment - when the edge of the curve is being rendered, which is when your hand moves slowest. Try taking the shots when you draw a steady straight line. If you have an iPhone you can take 120fps video, which would be more informative than a single photo.
     
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  10. surfaceproartist

    surfaceproartist Scribbler - Standard Member Senior Member

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    This is shot in slo mo video on an iPhone at 240 fps.* I just picked one frame. But the speed at which I draw the stroke doesn't affect the latency. The ink is always about the same distance away from the tip.

    *I thought I was shooting 200 fps, so I have to redo my calculation. Latency is closer to 80ms?
     
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