[vtk-developers] vtkDataSetAttributes::COPYTUPLE for GlobalIds and appending data

[John Platt]

Hi,

This problem also arises when an unstructured grid must be split into 
parts because the field data is not continuous, for example, stresses 
between two different materials. Appending the parts again for node 
labelling loses the global Ids (node numbers) .

vtkClipPolyData does not copy point global Ids which is reasonable 
because the data would typically need to be interpolated. But if the 
poly data consists solely of vertices, it is safe to copy them. 
vtkShrinkFilter does not copy cell global Ids; 
vtkUnstructuredGridGeometryFilter does not copy point global Ids (VTK 
5.10.1).

I would definitely go for an API on the algorithm which allows 
specification of attribute data to be copied.

Thanks.

John.


On 06/02/2015 20:33, David Cole via vtk-developers wrote:
> When I read "if COPYTUPLE for an attribute is 0, data is still copied"
> I think to myself, well that doesn't seem to make sense...
>
> I think (2) sounds like a better idea.
>
>
> 2 cents,
> D
>
>
>
> On Fri, Feb 6, 2015 at 3:12 PM, Dan Lipsa <dan.lipsa at kitware.com> wrote:
>> Hello all,
>> We would like the feedback of the community for the following problem:
>>
>> In an append operation, the GLOBALIDS array is not copied to the output
>> because, by default, vtkDataSetAttributes::COPYTUPLE is 0 for the
>> vtkDataSetAttributes::GLOBALIDS attribute.
>>
>> This behavior makes sense if appending datasets coming from different
>> sources, but it does work in a ParaView use case.
>>
>> In ParaView running with a remote pvserver configuration, data is processed
>> on MPI nodes, sent to node 0 and appended together there (using
>> vktAppendCompositeDataLeaves) and then sent to the client. In this case, the
>> GLOBALIDS arrays is valid, and should be preserved.
>>
>> We are thinking of two possible/alternate solutions to this problem:
>>
>> 1. Change vtkDataSetAttributes such that if COPYTUPLE for an attribute is 0,
>> data is still copied but it does not set that attribute as an active
>> attribute (using vtkDataSetAttributes::SetActiveAttribute).
>>
>>
>> 2.  Provide API for vktAppendCompositeDataLeaves (and vtkAppendFilter,
>> vtkAppendPolyData) that
>> specifies that the GLOBALIDS should be copied.
>>
>> Do you have any feedback on this?
>>
>> Thank you,
>> Dan
>>
>>
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