vtkGeneralTransform

[David Gobbi]

Hi All,

I'm planning to commit several changes to vtkGeneralTransform and
associated classes (including the venerable vtkTransform) either 
tomorrow or Friday.  The nightly builds might be unstable for a day or
two (hopefully not more).

The most important changes are as follows:

 1) The new vtkTransform has a SetInput() method, so that you can set
    a transform to be the same as an existing transform _plus_ whatever
    additional rotations/translations/concatenations you apply.  There
    is a pipeline mechanism to ensure that the transform will update when
    necessary.

 2) The vtkLinearTransformConcatenation (awful name) that I added recently
    will be deprecated and (soon) removed, because you will be able to
    concatenate transforms using vtkTransform instead.  Ditto for
    vtkPerspectiveTransformConcatenation.

 3) The internals of vtkGeneralTransform and the associated classes have
    been re-organized to reduce code duplication.

 4) vtkThinPlateSplineTransform is much more robust than it used to be

 5) a new class, vtkGridTransform, allows you to specify a warp
    transformation by defining an xyz grid of displacement vectors.


There is one thing which I am planning to remove: the
vtkTransform::Transpose() method.  The reason I'm doing this
is because matrix transposition is incompatible with the new 
SetInput()-style transform pipeline.  If your code uses Transpose(),
then you will get a warning message but your code should still work. 
You can still use vtkMatrix4x4::Transpose().

If anyone has any questions/comments about these changes or about the
existing vtkGeneralTransform class heirarchy and pipeline, I'd be glad
to hear them.

 - David

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

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