[vtkusers] Volume rendering with multiple scalars in one vtkImageData

Charles Boivin okeovtk at gmail.com
Thu Jun 30 13:43:27 EDT 2005

Hi Lisa, thank you for answering,

On 6/30/05, Lisa Avila <lisa.avila at kitware.com> wrote:

> You should be able to render vtkImageData with multiple components in the
> scalars using vtkFixedPointVolumeRayCastMapper. If you are rendering these
> as non-independent components (2 or 4 component) then you can also use
> vtkVolumeTextureMapper3D. The other volume rendering classes will not work
> correctly with anything but 1 component unsigned char or unsigned short.

Aah, that's the information that was missing. I am not using that
particular mapper. I will have a look at it, thank you.

> When rendering multiple components independently, you do need to specify
> parameters per component in the vtkVolumeProperty. It should not crash if
> you do not, but it may not produce an image.

That is good to know!

> You should be able to extract a single component from multi component
> scalars and render this. Perhaps these are not being assigned to the
> scalars in the point data, but instead are just some other field?

I think the fact that this was not working in my case is simply an
indication that I have something else wrong.. it should not be a
problem, I know. I am pretty sure it is extracted as a scalar in the
point data, but I will double-check.

Thank you for shedding some light on that topic,


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