[vtkusers] Possible bug: TransformFilter does not transform vectors for line polydata.

[Cory Quammen]

Evan,

I recall this being an issue that was reported on the bug tracker, but
can't for the life of me find it. Mind filing a bug report?

Note that it is probably only reasonable to transform the array that is
designated as the "active vectors" array, as one could have multiple
component arrays that do not represent a vector and therefore should not be
transformed by the vtkTransformFilter.

Thanks,
Cory

On Mon, Jul 25, 2016 at 7:06 PM, Evan Kao <tossin at gmail.com> wrote:

> Hello all,
>
> I attached a .vtp file of a line that has vector point data.  When I apply
> a transform filter (code is provided below), the points are transformed
> properly, but the vectors are not:
>
> Original
> Transformed
> [image: Inline image 2]   [image: Inline image 3]
>
> It turns out the vectors weren't transformed at all for some reason:
>
> Before                                                      After
> [image: Inline image 4]
>
> However, the vectors do transform properly when I'm transforming a 3D
> unstructured grid with tetrahedral and hexahedral cells.  I thought the bug
> might be related to the topology, but when I put the polyline through a
> vtkDelauany3D filter, the transform still didn't work correctly.  What's
> going on here?
>
> I should mention I tested this in both VTK (v7.0) and Paraview (v5.0).
>
> Thanks,
> Evan Kao
>
>
>
>
> Code:
>
> import vtk
>
>
> tf = (-0.0040248411422550, 0.9994518507299456, 0.0328602910252758, -0.0002179778201077,
>
> -0.9998799178301331, -0.0045139785455129, 0.0148247737823206, 0.2103193900724151,
>
> 0.0149649782420806, -0.0327966777307833, 0.9993500024295978, -0.0002392083616021,
>
> 0.0000000000000000, 0.0000000000000000, 0.0000000000000000, 1.0000000000000000)
>
>
> transform = vtk.vtkTransform()
>
> transform.SetMatrix(tf)
>
>
> transformFilter = vtk.vtkTransformFilter()
>
> transformFilter.SetInputData(input)
>
> transformFilter.SetTransform(transform)
>
> transformFilter.Update()
>
> output = transformFilter.GetOutput()
>
>
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-- 
Cory Quammen
R&D Engineer
Kitware, Inc.
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