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

[Evan Kao]

Ah, actually I think that was my problem.  I didn't consider that only the
active vectors were transformed.

Thanks,
Evan

On Mon, Jul 25, 2016 at 7:07 PM, Cory Quammen <cory.quammen at kitware.com>
wrote:

> 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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