[vtkusers] wrong sub-extent processed by vtkImageConstantPad if combined with vtkDiscreteMarchingCubes and MPI

[Grothausmann, Roman Dr.]

Still, the problem of vtkImageConstantPad persists when combining it with 
vtkContourFilter, same error reported when executing e.g.
https://github.com/romangrothausmann/VTK-CLIs/commit/c426432d7d73b5cf78a5bfff5ee33a75298926d6


On 25/11/15 15:04, Grothausmann, Roman Dr. wrote:
> I just noticed that vtkDiscreteMarchingCubes and also vtkMarchingCubes do not
> handle sub-extents correctly. It seems both filters do not handle the
> translation of each sub-extent. If the result is saved in a PVTP-file and opened
> in ParaView, the content of each VTP-file is placed over the others.
> In contrast vtkContourFilter does handle the translation of each sub-extent
> correctly, the content of each VTP-file is positioned correctly, see e.g.
> https://github.com/romangrothausmann/VTK-CLIs/blob/9eac8644101360d18f2ff70928d457aabddbbbf0/marching-cubes_MPI.cxx
>
>
> On 24/11/15 14:26, Grothausmann, Roman Dr. wrote:
>> Dear mailing list members,
>>
>>
>> Trying to cap the output of vtkDiscreteMarchingCubes by applying
>> vtkImageConstantPad on the input before does not work if running
>> vtkStreamingDemandDrivenPipeline by e.g. a vtkMPIController.
>>
>> If I run this program with the parameter for capping, i.e. employing
>> vtkImageConstantPad:
>> https://github.com/romangrothausmann/VTK-CLIs/blob/9eac8644101360d18f2ff70928d457aabddbbbf0/discrete_marching-cubes_MPI.cxx#L90
>>
>>
>>
>> I get an error such as:
>> vtkImageData (0x1868190): GetScalarPointer: Pixel (0, 0, 341) not in memory.
>>   Current extent= (249, 499, 0, 479, 0, 429)
>>
>> It seems that vtkImageConstantPad processes the wrong sub-extent. Would that be
>> a filter internal problem or of my code?
>>
>> Could the problem be related to the fact that I try to combine structured extent
>> (Index (IJK) based, not using ghost levels) with piece-based extent that uses
>> ghost levels?
>>
>> The problem even occurs when the extent is not extended at all.
>> The program works as expected if vtkImageConstantPad is avoided.
>>
>> Any help or hints are very much appreciated
>> Roman
>>
>

-- 
Dr. Roman Grothausmann

Tomographie und Digitale Bildverarbeitung
Tomography and Digital Image Analysis

Institut für Funktionelle und Angewandte Anatomie, OE 4120
Medizinische Hochschule Hannover
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D-30625 Hannover

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