# Detection of edge of a polygon

Actually I am working on some algorithm . Taking a seed point on the surface of a polygon. And propagate it considering the linked vertives. Suppose, v1 is my seed point. It has edge with v2, v3, v4 and so on. Next I am considering the link vertices of v2, v3, v4. Next iteration considering their links and so on. Now when viewed the behaviour of propagation of a seed point, it seems at some stage of iteration, some outermost layer points meet and forms a closed edge. Definitely one or a few of the outermost layer form a closed edge. I need to know at what stage the closed edgeis formed to avoid further iteration.
Thanks for any further suggestion. Pls ask me if needs further clarification.

[QUOTE=jenny_wui;1246993]Actually I am working on some algorithm . Taking a seed point on the surface of a polygon. And propagate it considering the linked vertives. Suppose, v1 is my seed point. It has edge with v2, v3, v4 and so on. Next I am considering the link vertices of v2, v3, v4. Next iteration considering their links and so on. Now when viewed the behaviour of propagation of a seed point, it seems at some stage of iteration, some outermost layer points meet and forms a closed edge. Definitely one or a few of the outermost layer form a closed edge. I need to know at what stage the closed edgeis formed to avoid further iteration.
Thanks for any further suggestion. Pls ask me if needs further clarification.[/QUOTE]

Once again, using that approach, every polygon will be a ‘ring’.
I don’t think that’s what you want.
Also, you could easily wind up with an infinite number of rings.

A couple of ideas:

. . . . 1) disregard single polygons as rings,
. . . . 2) find a way to spatially constrain the vertices relative to your seed point.
. . . . . . (otherwise you’ll get huge 100 point rings snaking all around your object)

• C

Yes, I am thinking some way to constrain the vertices relative to the seed point. Any further suggestion regarding this will be very helpful.