Isocontour

Find ISO-contour geometry in a 2D image using marching-squares, and sort the contour objects

This function ISOCONTOUR computes the isocontour geometry for a certain 2D image and isovalue. To Extract the isocontour geometry it uses Marching Squares and linear interpolation. Followed by sorting the contour geometry into separate contour-objects.

This function is the 2D equivalent of Isosurface extraction using Marching Cubes in 3D.
[Lines,Vertices,Objects]=isocontour(I,isovalue);

inputs,
I : An 2D image (grey-scale)
isovalue : The Iso-value of the contour

outputs,
Lines : An array describing all the Line-pieces of the isocontour
geomtery, with a N x 2 index list of vertices
Vertices : Vertices (Corners) of the lines M x 2 list of X,Y
coordinates
Objects : A 1 x K cell array with in every cell a list of indices
corresponding to one connect isocontour. If the isocontour
is closed then the last index value is equal to first index
value.