digitizer accuracy issue (ripples)

Discussion in 'Microsoft Surface Pro 3' started by wundram, Jun 24, 2014.

  1. wundram

    wundram New Member

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    I've been seeing issues with my surface pro 3 when I try to draw lines. If I make the stroke really fast it looks nice a clean, but if I draw it slowly it looks terrible, all zig zaggy. I know my hands are not that shaky. As an experiment I took a straight edge and used it to draw a series of parallel lines with the pen. Not drawing too fast, more like one second for each line. When I do this I get this weird grid ripple pattern (If you blur your eyes a bit, the grid becomes really apparent). This makes me think there is some issue with the digitizer that is causing a lot of the errors in my lines. I am wondering if this is particular to my hardware or universal. Or if it might be something that just needs a bit of calibration. You can see the pattern I got below. You could try the same experiment with any drawing program that supports the pen. I used sketchbook pro (which doesn't need any additional drivers, and doesn't work right if you install the wintab driver). I was getting similar results with clip studio.

    ripples.png
     
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  2. godson594

    godson594 Active Member

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    Maybe try the new Ntrig drivers. I just quickly did some lines and they don't look squiggly (did it in photoshop)- super zoomed in to show it.

    straightish.PNG
     
  3. Atomic Walrus

    Atomic Walrus New Member

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    Well-known n-trig issue. Everyone got caught up in the pressure sensitivity resolution mess and we never got to seriously discuss the actual major issues with n-trig that keep artists from using it:
    -Hover lag
    -High initial activation force (even if you can tweak the curve you probably won't be able to change this)
    -Wobbly slow lines

    [video=youtube;RKHLU0bjH_Y]http://www.youtube.com/watch?v=RKHLU0bjH_Y[/video]

    Basically you're using the touch digitizer to do the pen input, and wobbly lines are pretty common on capacitive touch input. Try finger painting slowly using an SP1/2 and you'll see the same wobbly lines. Apple's touch input shows less of this behavior, but their capacitive touch screens are easily the best out there.

    It works fine with faster strokes, but depending on your drawing style that may not be a viable workaround (nor is it something you have to work around with a Wacom digitizer). In some software you can apply corrective smoothing, but this introduces extra latency which is also undesirable. As the video description says, most people who don't use the pen seriously test a digitizer by making a few quick strokes and deciding that it looks good. When you actually use a pen input to do work you quickly learn that there's more to a good digitizer than handling fast strokes.

    Just to make this fair, Wacom has its own set of issues, the most significant being that edge accuracy. You need tons of bezel to get good edge accuracy with a Wacom digitizer (take a look at the Cintiq 13HD's bezels). A lot of people complain about tip offset, but I think if MS hadn't included such a terrible pen with the SP1/2 this wouldn't come up as much. Using a pen with the sensor closer to the tip like the Wacom Bamboo Feel improves overall tracking accuracy quite a bit. I even have an old Samsung pen from a first gen Note tablet that's a better pen than the one MS included.

    N-trig might be able to improve this with some driver-level smoothing (though they never have in the past), but that would increase the latency (the only way to apply smoothing is to average input over several input events, so you have to hold a certain number of input events in order to do it). Maybe they could use the 25-30ms they have over Wacom to apply the smoothing? Not sure if that would be enough.
     
    Last edited: Jun 24, 2014
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  4. godson594

    godson594 Active Member

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    %^&%*& I didn't read you were doing it super slow.

    NTrig isn't as good as the Wacom on my Sp2

    squig.PNG
     
  5. BillJ

    BillJ Active Member

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    Speaking as a medical professional, I could also argue that intentionally slow drawing is associated with muscular tremor that is unavoidable. The pen is simply responding to physiological tremor. I see the same phenomenon with my SP2.
     
  6. godson594

    godson594 Active Member

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    Lol.... That's certainly not my case... sp2 I never saw this problem and with pen and paper i'm perfectly straight...
     
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  7. riggi

    riggi Member

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    What happens if you place a ruler across the screen and draw a slow line with the pen against the ruler? Is it still wiggly? If so, then that would rule out muscle tremor.
     
  8. godson594

    godson594 Active Member

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    OP already did this - ((As an experiment I took a straight edge and used it to draw a series of parallel lines with the pen.))
     

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