This looks awesome and it will get even better!
Using the new “Wrap Solidify” effect (provided by SurfaceWrapSolidify extension) by Sebastien Andress you can ensure that discontinuous contours/missing pieces are connected to form a nice solid object.
Example on a very low quality image:
Input (obtained with simple thresholding, without any resampling, filtering, etc):
Result of “Wrap Solidify” using “Deep Hull”: the orbital wall is a nice continuous surface
I would expect that running solidification on the filtered image would provide very good quality segmentation.