CONTOUR3 3-D contour plot.
CONTOUR3(...) is the same as CONTOUR(...) except that the contours
are drawn at their corresponding Z level.
C = CONTOUR3(...) returns contour matrix C as described in CONTOURC
and used by CLABEL.
[C,H] = CONTOUR3(...) returns a column vector H of handles to PATCH
objects. The UserData property of each object contains the height
value for each contour.
Example:
contour3(peaks)