Currently, the polygon models that are created by the "Create Smoothed Polygon Model" command are ugly. They show single pixels as cubes, no smoth surfaces.
I examined the problem. The cause of the ugly surfaces is that a median filter is applied after a gauss filter of the segmentation. If the median filter is turned off, the resulting surfaces look much better (and are in fact smaller, because the decimation filter performs better on the smoother surfaces).