Extend multiple lines simultaneously

I’m designing puzzles and use Inkscape centerline trace to get the shapes as a vector. However, the shapes aren’t completely closed. Using Adobe Illustrator trace results in the same issue.
Trying to fix this in lightburn, I could extend every single line one by one but that’s a lot of work. Is there a way to extend all these lines easier? Would be nice if there is a feature similar to ‘auto-join selected shapes’ for lines. (auto-extend selected lines… )

Or does anyone have an idea how to do this differently?

I suspect the reason you’re getting disconnected segments is that centerline trace “dislikes” y-type or t-type intersections and the result is to lop off the branch from the original design. I realize this is not an answer to your query, merely a supposition. I see some contradictions to this supposition in your image, but that could be locations you’ve manually connected/corrected.

It’s a sort of topology puzzle that doesn’t easily present an answer.

Hi Fred,
I agree with your analysis; it’s certainly related to that. I use software that creates images like this one and then trace the lines. Creates cool puzzles but with a lot of manual work that I’d like to automate a bit…


A combination of blur, threshold and edge-detect in an outside program might do what you need.

Any luck with this?

No, that doesn’t work. The shapes are not closed and not supposed to be closed.

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