Nice smooth surfaces into Renderman

[slevy]

Probably the easiest way is to use Silvio's BezierPlot[] Mathematica package.
Example:

 << Geomview.m
 << BezierPlot.m
 catenoid[u_,v_] := { Cos[u]*Cosh[v], Sin[u]*Cosh[v], v };
 Geomview[ BezierPlot[ catenoid[u,v], {u,0,2*Pi}, {v,-1.5,1.5} ] ]

Then manipulate appropriately and save as .rib from geomview.
I just tried this, and the result looks very smooth.