Hi Yann

Likely the surfaces were not simply connected and thus the spherical mapping went off.

You mentioned there is no pp_surf.vtk and no pp_para.vtk surfaces, really? I am surprised that you got any procalign surfaces, as you are missing the starting point (the surf and para vtk's). Without those surfaces, you would not get anything. Did you try loading the pp-segmentations into a viewer such as 3D Slicer or itksnap? How do they look?

Martin