R_Bibb_Medical_Modelling_The_Application_of_Adv.pdf

176 Medical modelling
6.45 Extruded data to form solid computer model.
The second approach utilised CAD software (FreeForm ® ) that enables
the user to conduct virtual sculpture on three-dimensional computer models
using a touch-feedback stylus. The software tools mimic those of traditional
handcrafting. This makes the software easy to learn and intuitive to use,
particularly for prosthetists, and it has been successfully used by the authors
in other maxillofacial laboratory applications.
Initially, a smoothing operation was carried out, which produced an
effect similar to that obtained using the RP software. Secondly, the smoothing
function was used only over areas selected by the user. Finally, a carving
tool was used to carve away small areas of scarring locally. The effect is
illustrated in an exaggerated manner in Fig. 6.46. In practice, a combination
of these functions enabled the prosthetist to rapidly produce a surface that
met the needs of the individual case. The data was then cropped so the
physical model would form a good vacuum-forming mould. Then Laminated
Object Manufacture (LOM TM ) – see Section 5.8 – was used to produce the
vacuum-forming mould shown in Fig. 6.47.