[vtkusers] Question about visualization 3D image data with VTK

[David Gobbi]

The property needs a color transfer function and an opacity transfer function.
Please read all the comments in the example, the comments will answer
most of your questions. There is also a description of the volume rendering
process in the VTK textbook:

https://lorensen.github.io/VTKExamples/site/VTKBook/07Chapter7/#77-volume-classification

To keep things simple at first, you can use ShadeOff() and you can ignore
the gradient opacity function.  But the color transfer function and the opacity
transfer function are always required.

  David