youYou could have done that with openscadOpenSCAD, there are instructions for extruding.
Personally, i'dI'd just do a 1 altitude copy with this: http://www.thingiverse.com/thing:1981938Image 2 STL 2 Heightmap Mesh Converter Generator
, then rotate in scadOpenSCAD. it'sIt's called rotate extruderotate_extrude()
and is used for seashells.
in meshlabIn MeshLab you can use laplacian smoothLaplacian Smooth to depixelate/antialias it.