[Algorithms] Heightfield to NURBS conversion

[Christian R. M. K. <chr...@pu...>]

After lurking around for some months due to 'transient mesage'
replies, which I don't seem to get anymore, probably because
the list moved to sourceforge, I'd like to introduce myself:

I am Christian Körber, German, study Computer Science in
Hamburg and specialize in computer graphics and geometric
modeling. 

I have a question too:

Could anyone of you point me to an algorithm on heightfield
to NURBS conversion i.e an algorithm which takes as input
an heightfield and returns the control points of the NURBS-
surface which APPROXIMATES the heightfield to a user given
error?
I'd really like to avoid meddling with the later chapters 
of Piegl & Tillers NURBS book! Maybe you even know a pro-
gram?

Christian