Illustrator Tip #1: Corner Artifacts

Outlining and dividing a path in Adobe Illustrator 7 can lead to annoying artifacts when making knotwork. Correcting the problem is simple.

Corners are a problem

When your knots have corners, be they rounded, beveled, or square, Illustrator's Object|Path|Outline Path command doesn't produce what you might expect. Let's look at each of the cases. Here are the original corners you want to outline.

[line drawing]

Now we apply Object|Path|Outline Path. After the command, you'll find that there are little triangles at the interiors of the corners. I'd expect that there'd be a single control point where the border changes direction, but there isn't. Instead we get triangles. (I think I can see why Illustrator creates them, but that's not really important.)

[outlined paths with triangles in corners]

Getting Rid of the Artifacts

If the path you outlined didn't cross itself, getting rid of these artifacts is simple. Select the outlined path selected, apply Object|Pathfinder|Divide, then immediately apply Object|Pathfinder|Unite. This first separates the artifacts into separate objects, then unites them with the main line. Simple as that.

If your path crosses itself, as is common in knotwork, more work is required.

Apply Object|Pathfinder|Divideand then Object|Ungroup. You now have two separate pieces that are both selected. If you're careful, you can select just the interior triangles. Here's what they look like, with colors reversed for clarity:

[corners with little artifacts]

From here, it's simple but tedious: select a corner artifact and the surrounding line, unite, and repeat. You might need to do a select-drag to get all the pieces you need. If you get pieces you don't want, shift-click to deselect them.

In this case, I've united the middle corner.

[united corners]

If you've got a better way to deal with this, I'd be happy to know about it. It can be a real pain to do this when you're dealing with intricate knots with lots of corners.

Last updated 2 July 2004
All contents ©1999-2002 Mark L. Irons

Next: Tip: Aligning Irregular Shapes