Extract medial axis line

Hi everyone,

So I have this closed curve and thanks to a large number of definition available in this forum i got the medial axis of this closed curve.

What i am trying to achieve is extract only the middle part of this skeleton.
I've tried many ways to do it with lists mainly but with no success.

Here is an image that illustrates what i want.

The line in the yellow curve is what i want to extract.

Is there a solution to do this with any kind of closed boundary?

Thanks.

Attachments:

Medial axis.gh, 30 KB

Replies to This Discussion

Permalink Reply by Anders Holden Deleuran on February 20, 2017 at 7:14am

I describe a couple of methods for going problems of reducing medial axis transforms in this paper that might help, specifically this bit:

"By subsequently identifying points in which the remaining Voronoi line-segments connect in a node with a valence >= 3, we can construct a MA suitable for graph analysis by joining the linesegments into polylines which connect at these branching points"

Pretty much all these topological operations rely on identifying branching nodes (i.e. where more than three points overlap), through nodes (i.e. where two points overlap) and outer nodes (i.e. where only one point exist). With this information you can start sorting, joining and culling the edges. A large part in this is tolerance in terms of when two points should be considered the same. I wrote all this in GHPython, but think you should be able to do it with sets etc in standard GH.

Hope that helps..

Permalink Reply by Laurent DELRIEU on February 20, 2017 at 8:43am

A simple, to simple?, solution could be to calculate the distance from th middle of each lines from the closed curve and to select the farthest!

Permalink Reply by Raul Matagringo on February 20, 2017 at 8:48am

Hi,

just a naive approach. Maybe it helps some how...

Attachments:

Medialaxis.gh, 37 KB

Permalink Reply by Ponnou on February 21, 2017 at 6:49am

Thank you all for your time and help.
Thanks to you I've found a pretty good solution that work fine in lots of different situation.
Here's the definition for other people who may have the same issue.

Attachments: