3D Modules for GRASS

Dear GrassUser and GrassProgrammer,

  I'm interested in developing some 3D visualisation tools embedded
  into the XGRASS environment, esp. for geological purposes.

  The code should be portable between several architectures and using
  free code (the only one, witch is copyrighted is Motif).

  I'm looking now for free 3D libs, my favourite choice would be
  PEX.

  Who has similar approaches, are there at CERL similar modules under
  development, what are Your experiences with PEX, which libraries do You
  would prefer?

Thanks in advance....

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Dipl. Geol. Andreas Holz email: asholz@cip.informatik.uni-erlangen.de
Institut fuer Geologie und Mineralogie
Schlossgarten 5
91054 Erlangen
GERMANY