*zf*(*p*) :=*z*.*f*(p)

For smooth surfaces, a Morse height function will have critical points
where the tangent planes to the surface are perpendicular to the
direction *z*, namely local minima, local maxima and saddles.
Polyhedral surfaces will have critical points at the corresponding
piecewise linear structures.

Height functions play an important role in describing tight immersions of surfaces in space.

**See also:**

- Polar height functions

* 8/12/94 dpvc@geom.umn.edu -- *

*The Geometry Center*