# How to take out the overlap parts of curves

Hi all,

I am looking for a solution in GH that can take out the overlap curves(and surfaces if you can) and leave the boundary as a result.
I have images for examples. If it’s just couple curves would be easy to deal with in rhino, but I have over 4000 curves, therefore, I’m looking for a more productive way to achieve this goal.

Thanks much.

Peiming

“Region Union” Should be straightforward

do I need to add a plane?

Plane is optional, but curves must be on same plane. If not plug a plane.
All inputs must be flattened. It must work.

Thanks for the reply. what do you mean by flattened? should I flatten the curves in rhino or do you mean literally flatten all components in the gh?

If the curves are not planar, the above won’t work, but assuming they’re all pretty parallel to say the xy plane, you can project them onto the plane and perform your area calculations there using the region union/difference components without a great loss of accuracy…

This is what I have… It gave me a bunch of planes… Would you mind show me just the components for your methods? I can follow it and test it. Thank you.

Post some of your curves, it will be more simple to help. You can read this to know what to do

That’s right. Here are the layers. Thank you. layer percentage calculation.3dm (4.7 MB)

If the curves have different z values you can’t called them overlapped but if some of them are overlapped, Region component will create union and leave other curves

I’m sure each layer are flattened. And I’ve try Region Union. It just not giving me results as the screenshot I posted above… Thanks.

If you want quick result forget Grasshopper and use Illustrator; export each layer with square around (reference) as ai file,use union and you get the result in one second.
Export the result as SVG and import it to Rhino again

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It should… but somehow doesn’t
I tried to plug all the planes (heavy to compute) but same results.

Here you go
The problem was that some curves were self intersecting, like the one showed in the definition.
So I used rebuild curve, which might modify slightly the curves. Play with the multiplier to get closer to the actual curves. Althought the higher you go, higher the chances to rebuild the self intersecting curves

RegionUnion.gh (71.4 KB)

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Hi, it work! Thank you for the solution!

They were originally produced from Illustrator, but I only notice the overlappings when I processing them in Rhino. Why didn’t I thought of that… Thanks for the help!