[vtkusers] Normal Interpolation in vtkVolumeRayCastCompositeFunction

[Stefan Bruckner]

Hi!

In vtkVolumeRayCastCompositeFunction's CastRay_TrilinSample_Shaded()
shading is performed using the encoded normals produced by the gradient
estimator.

For the gradient magnitude, trilinear interpolation is performed, then
the gradient opacity transfer function is evaluated.

However, for the shading itself, the color values are interpolated,
rather than the normals itself.

I'd be great if anyone could give me a hint why this is done this way.
Would it be possible to perform interpolation for each of the normal's
components and then look up the value in the shading tables?

Thanks for your help!

--
Stefan Bruckner