they use 2D textures to get for example non-uniform translucency 3D-textures
The combined texture needs quite some time to be computed.
It would be very interesting, if Indigo could use the resulting data (you don't need to calculate it more than once).
Wouldn't be a good idea, to directly implent the whole converting part, though: 10-90 min processing...
For Maya users ( only...
), there is a plug-in, too 
