[vtkusers] volume rendering >1 component data

[David Gobbi]

On Thu, 16 Aug 2001, Lauren O'Donnell wrote:

> Hi all,

> I am trying out volume rendering of some characteristics of DT-MRI data,
> and volume rendering (in vtk3.2) only is supported for 1 scalar component.
> So I wrote a subclass of vtkVolumeRayCastCompositeFunction to render RGBA
> data by grabbing the image components rather than using lookup tables.

This makes a lot of sense.

> Second, is there any way to "trick" the existing classes into computing
> the gradient/normal information using one of the components of my data as
> the scalar input?  Perhaps setting the active scalar component?

Why not just change your class so that it calculates gradients/normals
from your alpha component?  I don't think it would make sense to
use the R,G, or B components.

> If anyone knows a better way to go about this, please let me know.

So far it sounds like you're heading in the right direction.
The ability to load RGB data would also be very nice for the
vtkVolumeTexture classes.

 - David