Best way to hunt down mistake in spline extrude?


Hi, been having major pain at work. My colleague sent me pattern design that I have to extrude in max, but the pattern is complex and often result in overlapping edges… are there any way to identify which vertices or edges are having trouble quickly? I have included screen cap on the design from AI below to show what kind of design issue I am facing…




You could put a STL Check modifier and it should give you an error count. You could explode each section to narrow down where.

Ideally I would create this in illustrator and then export as closed splines for 3dsmax to extrude.


thanks for the replay! the main problem is the file not created by me and I am quite sure that they are already closed spline… the thing is that if there are one or two out of all those lines that overlapped, the whole thing just not going to work… frustrating…

you mentioned explode each section, can you explain how it can help to identify the problem, please?
thanks again.


well theres a few different ways I could think of.

  1. detach sections of the spline, apply to all sections a SplineOffset modifier + Extrude modifier. Adjust the spline offset until you see where it pops back to a proper extrude

  1. apply a normalizespline modifier + extrude and increase it until you see the shape appear, it should give you an indication of where its overlapping

  1. grab points and shift them around until the shape pops back (extrude modifier on top)

  1. retrace it in Illustrator

  2. Use a 3rd party plugin (I think Sini Tools has a scene investigator and theres a guy on this forum that does some interesting Spline Tools that may have a built in solution but im unsure).


I can imagine the frustration, cause I’m just wasting hours on the exact similar issue on a vast number of ornamental mosaic tiles, which come from AutoCad. :roll_eyes: There are times two vertices are connected by two segments, forming a closed shape :tired_face: and only single way to find out was looking at the yellow first vertices, blindly deleting the segment and finding out there is another segment just over it. Since it is closed, you can’t find out what is going on by moving vertices. I was almost going crazy, why two vertices in the same shape aren’t welding?

Only way seems to be doing it one by one, and to spare time, I narrow down the possible vertices by working in groups. I mean I select the entire vertices turn them to corner vertex type .
Show End Result button must be on in the modifier stack to see if the shape is extruded correctly. When I see the effect correct, I undo the operation and deselect a few vertices and try again until a problem vertices appear.
I wonder if STL Check works for splines, but yes, it might show the problems on the extruded model. It will eventually find several open edges though. Some other error type display might help.
Good luck and wish you patience.


thank you for your help again!! will try these methods next time, the project got done because I got lucky finding out the error, but next time these methods might help instead of brute force. Thank you.


I got the project done at the end, I honestly got lucky or otherwise…