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  1. #1
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    Annoying pressure curve with Wacom Intuos Draw + Krita and FireAlpaca !

    I have tried various settings in Wacom Tablet Properties, and in Krita's pressure curve for tablet. No matter what, I do not have have a pleasant experience. The problem is that there are too sudden changes in the pressure curve (thickness, opacity, whatever). I know I do have a non steady arm/hand, but I'd assume pressure curve should be much smoother than this. I should mention that sometimes when I press gently I don't get any output only to a fraction of a second later have sudden output without me altering pressure, at least I don't feel like I do. Other times when I press even more gently I do have plenty of output.

    I have tried a number of curve tweaks in Krita, including much less steep output in lower input range, but then I get same non-smooth experience in the mid-range and up. If I change the wacom settings for tablet to less soft then I need to push very hard and that's not very desirable for either me or the nib and tablet surface.

    In following images ignore the smoothness of the spatial curve in FireAlpaca, I have max stabilizer value there and non in Krita. It's the usually non-smooth pressure curve that buggers me. I Just want to know if anyone has or had similar experience, and what you did about it.

    http://imgur.com/OeZFeFI
    http://imgur.com/8afRw0N
    http://imgur.com/rCM8KCy
    http://imgur.com/RAql5Ix

    Off topic: I created topic here as I didn't find any (sub)forum more fitting than this. If I'm wrong, do move to wherever more fitting.



  2. #2
    The best place for Krita related questions is the KDE subforum for Krita.
    This looks strange indeed. Have you tried shrinking the entire curve vertically ?

    Name:  Screenshot_2017-06-04_20-53-00.png
Views: 162
Size:  3.3 KB



  3. #3
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    Originally Posted by ChameleonScales View Post
    The best place for Krita related questions is the KDE subforum for Krita.
    This looks strange indeed. Have you tried shrinking the entire curve vertically ?

    Name:  Screenshot_2017-06-04_20-53-00.png
Views: 162
Size:  3.3 KB
    No, and although the curve doesn't make much sense to me, I just did for the heck of it. And while indeed the output is undesired, the gaps remain as before.



  4. #4
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    If the Wacom Tablet Properties exposed to users the (editable) pressure curve that is output to applications, then I could probe and "debug" in Krita to see where the pressure is undetected/transposed, if there IS a failure. It would be nice if I knew which, if any, of the soft/firm levels in the properties dialog represent a 1:1 line. If true, I would think the middle (default) one. Or does each level represent a non-linear curve ? Anyone with a clue ?

    I haven't looked if the wacom software bundle provides any kind of pressure debugging feature, so it's on my to-do list. But if anyone has any information please speak up, thanks.

    Also anyone that uses the Bamboo/Intuos (different from Intuos 3, 4, 5, or Pro) please tell me and other readers that may be curious if you experience natural (as opposed to disconnections/gaps in) brush size/opacity/etc transitions in the lowest pressure levels.



  5. #5
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    Nevermind, I've learned to deal with it by using only certain brushes with tablet. It (Krita in this case) may need custom/tweaked brushes for things to work better with tablet. I'll look into it sometime maybe.



  6. #6
    By the way, does it work better with other applications like Blender ?



  7. #7
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    I hadn't done anything with tablet in Blender previously. Now that I tested GPencil, I experience about the same pressure output as in the 2d applications, which I experience as slightly less fluctuating. Maybe due to resetting the tablet preferences ?

    All I know is that some brushes in Krita almost paint nothing visible at all even when I do press relatively firmly, while other brushes paint plenty with lighter press. This is the case even between some ink brushes. Ink_brush_* vs Ink_gpen_* forexample. Literally night and day respectively.

    Possibly some of the brushes in Krita which aren't configured properly. Maybe they're based on some particular curve that Wacom tablet driver applied at some point in time, or maybe curve that the Intuos Pro line's driver (setting) may apply, which the non-pro Intuos' (formerly known as Bamboo) do not apply. Who knows, I don't.

    The main problem I experience, which irritates me greatly, is that even if I drag the "slider" for pressure sensitivity in the driver settings to the far left (meaning most sensitive) AND drag the left node in Krita's tablet curve setting far up (so that slightest press generates a thick visible line), I STILL cannot press very lightly and reliably draw an intact line (i.e. without gaps). While the nature of "normal" pencils is quite similar, ink brushes are whole different animals, and with those you expect to see ink on paper with slightest contact. And that is where the pen (or driver if that is the case) fails me.

    I have found a front-end application for wacom settings files that is supposed to provide a GUI for you/me to tweak the curve that is output from the driver to the graphics/etc applications. In the upcoming days I will try it and see whether the driver's default curve setting is to be blamed for my unnatural draw/paint experience, whether it's a mechanical calibration issue, or if it's simply so that the first/lightest pressure level detected by the pen is above the lightest pressure I'm able to deliver.



  8. #8
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    So today I tried the pressure curve tool. Link: https://blackink.cz/tablet-pressure-curve-tool

    As I suspected, the middle level in "Wacom Tablet Properties"->"Pen"->"Tip Feel" corresponds to a line, but not 1:1, since the output starts (at 0) when the input is considerable (i.e. when input is well above 0).

    Further, there is a threshold range which seems to represent the range of force in which each stroke need to either start with or reach in order for the driver to start sending input to applications. I didn't examine it thoroughly, but the single test seemed to indicate that.

    Also, in this application, the input is represented by the y-axis, while the output by the x-axis. I don't know why, but that's how it is. Therefore, the threshold range mentioned above, is of input kind (y-axis = input).

    I'm now able to draw more consistently the thinner/-est lines without constant gaps. Of course the very thinnest ones, being on the border of the lowest level of pressure the pen can actually detect, will sooner or later result in gaps, and that is to be expected. But custom/better brush presets (curves) can help a little bit.

    I read somewhere that the driver for the Intuos Pro and Cintiq lines of tablets exposes the pressure output curve to users. Us mere Intuos users have to track down third-party software (or write our own) to access that without editing the preferences xml file directly.

    edit

    Actually, the threshold stuff is like this: the stroke is initiated when input pressure reaches Upper Threshold, and finished when it reaches Lower Threshold.
    Last edited by xol; 19-Jun-17 at 06:31.



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