Intersecting Curved Cut Lines

Sometimes you might get an error for a very “normal” case like below:

Crease line intersects a curved cut path

If you zoom it closer, you’ll see that the crease line actually perfectly ends on the cut, but you still get the error:

A close-up version of the problem intersection

You might also notice that Origami shows another point next to the intersection that lies outside the cut line. So what happens?

Origami Works With Straight Lines

That’s it. Origami converts curved paths to straight segments before processing the dieline. See the example below:

Now you should start getting it. Here is your crease line perfectly ends up on the curved cut:

The intersection of a crease line with the curve and its segmented version

As you may see, the crease line doesn’t really reach the cut segment, so you get the warning. Origami still meets the ends and extends the crease line a bit, but the process is quite complex and may affect other elements of the dieline.

So What To Do With This?

Exactly as with misaligned elements, we need to tell Origami that this particular point is important and should be there even after converting curves to segments. In order to do so, we need to add a point to the curved cut, where the crease line intersects it.

Here’s what happens:

Adding a point to the intersection location re-arranges the segments

Origami still converts the curve to segments, but this time there is a fixed point exactly where the crease line comes to the cut. Adding an extra point helps Origami to segment the curve properly and avoid the problem.

Here is the updated dieline from the top of the page, two extra points added:

No more issues after adding two extra points to the curved cut line

Adding two points to the middle circle cut resolved the problem.

Not Just Crease vs Cut

This might also happen to a cut vs cut intersection, as Origami still converts any curved cut to segments. It is a good idea to add extra points for any intersection to control the exact location of where it happens.

Once again: Origami can do this for you and adjust those little misalignments. In most cases this works just fine and sometimes you don’t even notice it happens. However, in some rare cases such adjustment may affect the dieline and lead to “impossible shape” errors. In this case you should first check the misaligned points and curved cuts intersections — the problem is likely to be there.

Want More Hints?

Empty Layout — why there is no dieline visible?
Path Is Not Closed — the dieline needs a solid, continuous outline path;
Intersecting Holes — holes must not overlap;
Overlapping Lines — cut and crease lines must not overlap, as well;
Outside Hole — all holes must be inside the outline path;
Invalid Crease — crease lines have limitations;
Almost Vertical/Horizontal — crease line is probably misaligned;
Impossible Shape — some shapes simply don’t exist;
Misaligned Elements — ends must meet, perfectly;
Elements Are Too Small — keep dieline paths simple;
Interesting Curved Cuts — it might not be easy;
Triangulation Failed — Origami fails to make a 3D mesh of a dieline;
Z–Fighting — what to do with overlapping polygons.

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