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From: Chen-Ket on 20 May 2010 12:49
Hi,

I have the x and y data of a 2D surface. I want to plot only the edges of this surface. How can I do that?
From: Walter Roberson on 20 May 2010 14:33
"Chen-Ket " <chen-ket.chai(a)eng.ox.ac.uk> wrote in message <ht3p60$paa$1(a)fred.mathworks.com>...

> I have the x and y data of a 2D surface. I want to plot only the edges of this surface. How can I do that?

There is no unique answer unless you constrain the "edges" to be a convex shape surrounding the points: if you have that situation, then you can use a convexhull routine.

If you do not wish your shape to be convex, then consider that we could take whatever shape you think is the answer and we could put cuts into and jags out of that shape (as long as we do not touch the existing points), and the resulting shape would be as valid given that data as the shape you thought was the right one. You could even make an arbitrary cut through the shape and say that the "real" edges follow that cut, as chances are that there is a line that would go the could without intersecting anything.
From: fabio freschi on 24 May 2010 03:41
You can first triangulate your data with DELAUNAY or DELAUNAYTRI and then check for the edges that belong to one triangle only
Fabio
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