Illustrator PDF Export Turns Curves into Segments

[VahePogossian]

Hello, I'm facing an annoying problem in Illustrator that I seem to be unable to solve. If someone could help, I'd be very thankful. I have this shape made out of curves:

As you can see the curves on the arches are smooth. When I do a PDF export, this is what I get:

I have no idea what's going on. I have played with all the PDF export settings and compression options. Nothing seems to be working. Someone please help.

[Mylenium]

Well, the answer appears to be pretty much in your screenshot itself: Since there aren't any actual control points visible, it's likely that the paths haven't been expanded and cleaned up properly, causing teh export simply to do an on-the-fly conversion with insufficient defaults. You need to spend some work on that, including possibly subdividing the paths/ inserting points to stabilize them further.

Mylenium

[VahePogossian]

Do you mean I have to turn the paths into shapes with the Object>Expand command, for it to work?

[Ton Frederiks]

Are these simple curves with a few anchor points?

Can you show a direct selection of one of these paths with the anchor points visible?

[VahePogossian]

Hello, thanks for your help. Yes, these are true curves, attaching a screenshot  with anchor points:

[Ton Frederiks]

That looks perfectly normal and clean to me.

If the pdf looks problematic in Adobe Reader or Acrobat there is something weird going on.

Try if copying into a new document works. Restarting and resetting Prefs is something to try.

https://helpx.adobe.com/illustrator/using/setting-preferences.html

[VahePogossian]

Just made a new post, check it out, it's an interesting find.

[Monika Gause]

This is a simple gradient on a stroke, right?

In which application did you open the PDF after exporting to take the second screenshot?

(trying to find out if this is caused by Illustrator's export or the other app's import)

[VahePogossian]

Hey there, thank you for your input.

Yes, that's correct - it's a simple gradient on the stroke. I'm using normally normally using Microsoft Edge to view PDFs. But I did try other viewers such as Google Chrome and Adobe Reader.

[VahePogossian]

Update: Fresh day, fresh coffee and I seem to have found the problem.

This is caused by a combination of Align Stroke position and Stroke Style choice. See the following PDF export:

Now the question is why is this happening when the stroke is a gradient and it's aligned to the middle... Is this a bug?

Interestingly, when I export a simple JPG or PNG, all the curves are smooth. This only shows on vector PDF export.

[Ton Frederiks]

That looks like a bug. Good to see that you found the problem.

Can you share that file? I find it hard to reproduce.