[vtkusers] volume rendering question

[Rodolfo Allendes Osorio]

Hi all,
 I've been trying to use vtk to render volume datasets downloaded from the volume library... to do this, I've downloaded the original *.pvm files, used the tool provided on the same website to convert them to raw format (pvm2raw) and added a header with information on the grid size, spacing etc...

then, I simply modify the SimpleRayCast example to load any of the volumes, but dont seem to get any nice renderings of the data...  I've been playing with the values of the opacity transfer funcitons, but dont seem to have any effect on the rendering... so, if anyone has used these datasets before, could you pls tell me if i'm forgetting some sort of preprocessing or anything that would make the data look nicer?

thanks