[vtkusers] Re: vtkImageData & tensors & filters

[David Gobbi]

Hmm... nonlinear transforms and tensors.  I thought about adding
support for tensors to vtkAbstractTransform but wasn't sure if
anyone would use that feature, so I just made the transform's
Jacobian available so that people programming in C++ can do the
tensor transformations in their own code.

Modifying vtkImageReslice to deal with vector & tensor images
correctly... that could be fun.

I'm not 100% certain that >4 scalar components are supported in
vtkImageData, I've never actually tried!

 - David

--
  David Gobbi, MSc                       dgobbi at irus.rri.ca
  Advanced Imaging Research Group
  Robarts Research Institute, University of Western Ontario

On 28 Jun 2001, Alexandre Guimond wrote:

> On Thu, 28 Jun 2001 04:20:37 -0400 (EDT)
> David Gobbi <dgobbi at irus.rri.ca> writes:
>
> > Hi Alexandre, Christina:
> >
> > I don't think that anything apart from perhaps some new imaging
> > filters is required to support tensor images.  Most of the
> > existing filters will already accept any number of components
> > per pixel, so you just need to use images with 6 (or is it 9?)
> > components as needed to describe the tensor.
>
> I though scalars were restricted to 4 chanels.  Did that change?
>
> > No changes to vtkImageSource should be necessary, as far as I can
> > see, as long as >4 components are already properly supported.
>
> So I guess it is new.  Wonderful!
>
> > Could you make a list of operations you'll need to be supported for
> > tensors?  I'm not one of the 'vtk folks' but I can probably offer
> > some advice re: implementation.
>
> I don't have an exaustive list now.  I'm just starting to play with
> it.  For the moment I do need math operators "+", "-", and composition
> with tensors, and "*" and "/" with scalars, and something similar to
> vtkImageShrink.  At some point I'll also need something similar to
> vtkImageReslice that would reorient tensors aswell as move them
> according to a given transformation.  For non-rigid transforms, it
> should also be able to modify the tensor appropriatly.  I don't really
> know yet what that implies in details; I'll have to figure it out at
> some point.
>
> If it's true with the 4 chanels thing, the parts missings are tensor
> composition and the vtkImageReslice.
>