Correct usage/explanation of trisurf

Hi all,

I'm trying to get a 3D representation of a pixel-by-pixel depth map. I have a matrix which specifies the locations of triangle vertices and the index of the triangle it belongs to(so, as I see it, x & y). It looks something like this:

1 1 3 3

1 0 2 3

0 2 2 0 where 0 means the pixel is unallocated to a triangle

and another matrix of the same size which has the depth of each vertex (the z). I've been creating my mx3 triangle matrix using the index of each triangle. I put this into trisurf with a meshgrid for the x and y, and the depths for z, and I get a (to quote Full Metal Jacket) "modern art masterpiece" with triangles all over the place.

Can any one give me a tip on how to transform the x&y index matrix into a usable mx3 triangle matrix? A bit of background onto how the image is actually constructed from the mx3 and the x/y/z matrices would also be really handy.

Cheers, Andrew