Finding the coordinate values at the boundary of an irregular matrix

Hello!

I have an XYZ matrix of data which describes a complex shape. I want to find the XY coordinates of my data which correlates with the perimeter of this shape. I want to use the output as a constraint for delaunayTriangualtion http://uk.mathworks.com/help/matlab/ref/delaunaytriangulation-class.html Currently, the triangulation uses the convex hull which is too crude and fills the concavities between the shape.

Using the boundary function http://uk.mathworks.com/help/matlab/ref/boundary.html I can create a boundary which tightly follows the perimeter of my shape, however the boundary provides a single column of data when I need a pair of points for the constraint. It seems like it should be a trivial task but I've looked but haven't found a method that allows me to extract the XY coordinates on the shape's perimeter. Is there a way to go about this?

I've attached an image for clarity. The blue is my data distribution, the orange the convex hull, and the green is the boundary create through the boundary function. Ideally i'd be able to find the XY points at the green boundary.

Many thanks!

[KSSV]

Attach your data...it can be achieved....