Blob Brush Creating Small Unattached Paths

[Tommy St]

Hello. I have noticed that my blob brush tool often creates a lot of very strange acute points and loops. Typically it isn't a big deal since I smooth them away, but sometimes it creates a few very small unattached shapes in addition to the blob. They are extremely small, and are typically two or three anchor points. Because they aren't connected to the main blob, I cannot smooth them away, and have to manually select them and delete them in order to remove them which is very annoying. I assume this is some kind of calculation error when using a tablet with pressure sensitivity? 

I very much would like the blob brush to not create any strange actue points, random loops, or other unepxected shapes other than the main blob. 

I am using a Wacom Intuos on a 2019 Mac Book Pro. I've attached screenshots. Note the screenshots are zoomed in as much as is allowed in Illustrator.

[Tommy St]

Can someone from Adobe at least confirm this is happening? I feel like this isn't the intended functionality for the blob brush.

[Abhishek Rao]

Hi @Tommy36537612v1by,

Thanks a lot for sharing the detailed explanation and screenshots. From what you've described, it does sound like the Blob Brush might be interpreting quick or slight pressure changes from the tablet as separate strokes, which could be why those tiny, unattached paths are being created.

To help narrow this down, could you please confirm the version of Illustrator you're currently using and also check if your Wacom driver is fully up-to-date? You might also try temporarily switching off pressure sensitivity in the Blob Brush options and see if that prevents those extra points from being generated.

Let me know how it goes after trying that, and I'll be happy to check further with the team if the issue continues.

Looking forward to your update.

Abhishek

[Tommy St]

Thank you for your reply!

My Illustrator version is 29.5.1 and all of my Wacom drivers, both software and firmware are up to date.

I am only making a single stroke, usually overlapping on itself in order to create a solid shape (not a compound shape). I do not lift up the pen. It doesn't happen on every stroke, maybe 1 in 10. I notice when after I create a solid shape using the blob brush the toolbar recognizes it as a Group, not a Path. 

I tried turning off the pressure sensitivity in the blob brush settings, and it appears to not create the issue. But I do need to use pressure sensitivity in my work, so that isn't a viable option for me.

If I were to guess at the cause of the issue, I think whatever solver function that figures out how to create a shape from the blob brush tool input sometimes fails when it may be when using varied pressure and overlapping strokes.

I've included a few more screenshots as examples.

[Kurt Gold]

I can reproduce the issue even when drawing with a simple mouse without pressure sensitivity. Specifically, if the fidelity is set to (most) accurate in the Blob Brush Tool Options. Usually, it gets considerably better when the fidelity is set to default (middle of the slider) or smoother.

Not sure if that would be a viable option for you.

[Tommy St]

Thank you for this confirmation. Glad it isn't just my current set up.

I tend to exclusively use the blob tool on the smoothest or second smoothest setting and the little erroneous shapes are still created. If you can reproduce it without pressure sensitivity, then that means the issue is likely the tool itself --not the tablet, nor any other hardware-- and the tool settings only slightly modify how frequently the issue arises. 

Can this issue be added to a bug list? I don't think this is the intended functionality of the blob brush. 

[Kurt Gold]

You can report it as an unexpected behaviour at https://illustrator.uservoice.com

I rather doubt that the issue will get top priority soon. So, in the meantime you are looking for a workaround to clean up the flyspots as fast as possibe, I suspect?

It could be corrected with an action or even with a graphic style.