intersecting image with plane

I have used the "surf" function to turn a grayscale image into a surface where xy are the original xy coordinate of the image and z is the light intensity at that image. I want to find the curve where this surface intersects with a plane z=(some number). Ideally a function for this curve would be best, but the coordinates of all the pixels would work too. Anybody have an idea of how I can do this?

Answer 1

[John D'Errico]

So you want to compute a level curve? Why would you not just use a contour plot to do that? If you want the curve itself as a polygonal path in the (x,y) plane, then:

help contourc