Rotation incremental error after save

[sPretzel]

I am seeing an incremental error that is only visible after saving and reopening the file, when doing Object>Transform>Rotate.

The attached images are for the following example. Some type "hi" is written on a path (circle), starting at zero degrees on the right hand side (black, not quite visible in the pictures). Then two cases are shown:

-The black object is copied, aligned with the original, and Object>Transform>Rotate with Copy in increments (10 degrees here) up to 180 degrees.

-The black object is copied, aligned with the original, and Object>Transform>Rotate once by 180 degrees.

After that, both match at 180 degrees on screen. I save, close the file, reopen it, and there is a mismatch as observed on the attached pictures. This is for CS4.

I have tried with 5-degree increments and see less of an error, but it is there too.

Because this is rotating and comparing the same point on the circle, I suspect it is not related to Illustrator approximating circles with 4-point Bezier curves.

[Jeff Witchel, ACI]

I'm surprized Illustrator CS 4 works on any computer at all today. It's over 12 years old. Can you tell us about what system you're using?

[sPretzel]

What would be helpful is to see if anyone can reproduce this error on any version of Illustrator. And if so, whether they have ways of mitigating it.

[Ton Frederiks]

I cannot reproduce that, works fine for me in CS4 (Yes Jeff, don't ask how, but I can still run CS4 on Mac OS Mojave)

See attached PDF (which can be opened in Illustrator).

[sPretzel]

Hi Ton. I looked at your pdf but only see one set of "hi"s, no "hi"s underneath.

Let me give more description on what I did. I start with a black "hi" typed on a circle at zero degrees. I copy that hi and make it blue. Then I Object>Transform>Rotate (click Copy in the Rotate popup) it in 10 degree steps until I reach 180 degrees. Then I start with the black "hi" at zero degree again but Object>Transform>Rotate (click OK) it once for 180 degrees and make that pink. On screen, both are right on top of each other at this point. I then save the file. When I reopen, I see a slight shift at 180 degrees, as pictured in the attached images.

[Ton Frederiks]

"I looked at your pdf but only see one set of "hi"s, no "hi"s underneath."

Just deselect the green hi in the layers panel.

[Kurt Gold]

I cannot replicate it either (tested in AI CS5 and AI CC 2020).

It may be caused by some kind of (inadvertent) misuse of the Align to Pixelgrid option, but that is just a guess.

[Ton Frederiks]

CS4 did not have the Align to Pixel Grid option.

[sPretzel]

Thanks for trying to reproduce the steps Ton and Kurt. Just double-checking: you both saved the file, closed it, reopened it, and then reported your findings, right?

[Kurt Gold]

Yes, I did follow the experimental set-up that you described in your initial post.

[sPretzel]

I had reported a long time ago here some position shifts happening when reopening a file and an Adobe employee had reproduced it and confirmed it was a bug. I will investigate more. If I put a larger concentric circle around the circle with type on (so the type box cannot interfere with the dimensions of the object during rotation, in case it did), group the two circles, and rotate the group in 10 degree steps, I don't see the issue anymore.

[Ton Frederiks]

If you open my file in Illustrator CS4 you can verify my findings.

[sPretzel]

I did Ton. I saved it in AI as .ai and reopened it and didn't see a shift!

[sPretzel]

Very puzzling. I still haven't got to the bottom of this problem.

By the way, is it possible to apply the same rotation as Object>Transform>Rotate to Type on a Path by using rotation in Distort & Transform>Transform FX and get the same result? The FX rotation seems to work like Object>Transform>Transform Each and appears to take into account the text box in addition to the circle (in my type on circle path example in the original post); this displaces the centre point (used as centre for rotation) and yields a different result.

[Ton Frederiks]

Yes, the Transform Effect includes the text when calculating the center transformation point, the result is indeed different.

[sPretzel]

If anybody else tries this out and reproduces the steps described in the original post, in any version of Illustrator, please report your findings here as it is still an open issue on my end (with no clue as to what is causing it). Thanks.

[Kurt Gold]

You may share one of your .ai files that has the issue.

Maybe it won't help to unravel it in this case, but sometimes it can help to reproduce something that cannot be reproduced due to some unknown facets.

[sPretzel]

Hi Kurt. I'm attaching the file I used to create the images in the original post here (saved as Adobe PDF). I put additional comments in the layers' titles so you know what I used for what (if that's good English!).

[Kurt Gold]

Thanks for the sample file. I can see the slight shifting.

The problem, of course, is that this is not the original state as you mentioned a couple of times that it only occurs after saving and reopening the file.

I'm still not able to replicate the issue in various versions of Illustrator. Do you have some more recent versions of Illustrator and have you already tested if it happens there as well?

By the way, what operating system are you using?

[sPretzel]

Perhaps you can try to replicate the issue with the pdf opened in AI, using the bottom layer and rotating/copying it in 10 degree increments (steps in OP). Yes, when I create the artwork, everything is fine and dandy, but once I save and reopen, things go wrong.

I have been doing various tests on my end but have not concluded to anything in particular yet.

I don't have other versions of Illustrator. As I said, I have encountered shifting issues upon opening files before and reported here, and that was an issue that was reproduced by Adobe staff. I don't know if that could be related because it was not quite similar. Unfortunately, Adobe seems to have removed older posts in the forum as the link no longer works.

I use Windows 10.

[Kurt Gold]

I tried to reproduce it in the sample file, immediately after you provided it. To no avail.

I'm afraid the issue is a hard nut to crack at the moment.

[sPretzel]

Comparing the last "hi" in blue at 180 degrees (in increments of 10) and the first "hi" in blue at 0 degree, I can see for the 180-degree "hi" a slight shift of the centre bracket horizontally, as well as a vertical shift of the guide line that is supposed to sit flush with the path (the tangent, so to speak, or what mimicks the 0 baseline). The centre bracket has moved to the left and the tangent has lifted up from the path. The path itself is where it should be (click on the anchor point to check). Zoom at 6400% to clearly see it.

I can reset the vertical shift by dragging the bracket across the path (manual flip) and back. But this is not precise and I end up shifting the text sideways in the process. Flipping via Type on a Path Options does not reset the vertical shift!

I have attached three pictures showing this. The first shows the shift for the blue "hi" at 180 degrees, the second is a zoom-in on that, and the third is the first "hi" at 0 degree which does not have this problem.

[sPretzel]

I added some extra detail to the previous post, with images. If anyone has seen this occur in their version of Illustrator, please chime in. Thanks.