Use the outputs from any of the contour plot functions to produce a table of (x,y) coordinates of the contour lines organized by contour level and group.

[cm, h] = contour(___);
contourTable = getContourLineCoordinates(cm);
--or--
contourTable = getContourLineCoordinates(h);

contourTable =
Level.........Group..........X............Y
____________________________________
-5.8504.........1..........0.44266....-1.75
-5.8504.........1..........0.375........-1.8038
-5.8504.........1..........0.25..........-1.8526
-5.8504.........1..........0.125........-1.8498
etc....

Where Level is the contour level in the LevelList of a contour object, Group is a grouping variable for contour levels, and (X,Y) are coordinates along the contour lines.