Polyline curve issue

Hello All,

As you guys can see, I am working on the network of rivers, and buffers of those rivers I am trying to create. But the issue is after polyline offset component to the curves, I use the boundary surfaces component to get the surface of the buffer, but I got the big area enclosed by the buffer which I do not need as you can see in the image. So what I want is just the surface of buffer of the river not the big area enclosed by the network, thanks! The attachments are the screenshot and GH&Rhino files, please give me some suggestion and really appreciate it!

4 river buffer.3dm (11.4 MB) river buffer.gh (5.3 KB)

Someone can help?

You’ve told us what you don’t want, it is unclear what you do want. As far as I see what you have is the expected result of boundary surface. If finds closed zones from input curves and makes surfaces from the zones. The surfaces in your image are the only closed zones in your curve network. So what are you trying to achieve?

hello Michael,

Thanks for your reply, I am sorry that my quesiton is unclear. What I want is the buffer zone of the line( the river network), not the surface enclosed by the network of line. As shown in the image, I have noted with blue text, I just want the line buffer area. Is that clear? Thx again!

You’ll need to provide the both output curves at the same time and reduce some control points before connecting to the Boundary Surface .

river buffer_re.gh (378.3 KB)

1 Like

It is also possible to use just Clipper

@wumingbang, the term buffer was not very clear I didn’t know it was just an offset. “A good drawing is worth 100 words”


Hello Kim,

Again thanks for your help. It looks good on the image you posted, but I have trouble openning the GH file you sent, can you just tell me what is the component name next to Boundary Surface? I cannot find it on the curve part. thank you so much!


Hello Larent,

Thanks for your reply, and I will improve my question next time, and I will try your way, thanks so much!


No problem, just a remark on Clipper.
Clipper is working in Integer so double are scaled internally depending on the Tolerance you gave. So it is like it works in Pixel, as you seems to work in meter it will be fastest to no put a tolerance like 0.001 (1 mm). I put 1 m and it seems enough. It is up to you to choose the tolerance that is appropriate to your work.

Reduce component(Curve–>Util–>Reduce). I belive it’s a vanilla GH. What version of rhino & GH are you running?

Not, it’s not clear. What does “buffer zone” mean? If you’re referring to the watershed area that feeds each river(?) then it seems to me you need the mountain ridges between the valleys to define them.

Got it, thanks Kim. You really help me a lot!

Hello Joseph,

I have figured out the solution, and sorry for the probel is not clear, I will do a good drawing next time, thanks!

Thank you Laurent!!!