[vtkusers] volume rendering with an arbitrary user-defined opacity function

[Rajan Joshi]

I am interested in performing volume rendering on a grayscale volume 
using another grayscale volume as the opacity function.

After searching through the VTK documentation, I could only see methods 
for defining piecewise continuous function dependent on the intensity of 
the grayscale volume to be rendered.

Any help will be greatly appreciated.

rajan joshi