[vtk-developers] vtkProcrustesAlignmentFilter

[Will Schroeder]

I want to make sure my understanding is correct: you want to process a 
group of data sets as a single data set?

Based on my understanding this means the filters would have to be modified 
to loop over the set of inputs, or a new type of data set, call it 
vtkCompositeDataSet, would have to be added (subclass of vtkDataSet) that 
would collect multiple datasets inside of it.

The first is hard because it means the streaming would have to be 
rethought, update process, awful...

The second seems better except that the filters that process this 
vtkCompositeDataSet do stuff like output->GetPointData()->GetScalars() 
which returns an array of contiguous values corresponding to the points. 
This has to play in conjunction with GetNextCell(), etc. So how do you make 
the vtkCompositeDataSet seem contiguous? I think it is doable but not trivial.

There is a third option I saw Gala Wind from NCSA do: if I remember right, 
she created a filter that took the equivalent of a vtkCompositeDataSet, 
plus an input filter, and internally applied the input filter to each of 
the datasets in the composite. This doesn't work well in the pipeline 
update process.

Please enlighten me if I am confused here. The second option is what I have 
been thinking about with regards to multi-block structured grids which are 
quite common. Something like vtkCompositeStructuredGrid 
(vtkMultiStructuredGrid ???).

Will


At 12:53 AM 1/16/2002 +0000, John Biddiscombe wrote:
> > How about vtkDataSetCollectionDataObject?
>
>That's better.
>
> > It struck me: wouldn't it look odd to have both this and
> > vtkDataSetCollection in VTK?
>
>Not really. Plenty of other strange things already in there.
>
> > Is there some way of instead deriving vtkDataSetCollection from
> > vtkDataObject? (while maintaining backward-compatibility)
>
>Multiple inheritance. (Backs away to avoid sharp hiss caused by Kitware
>folks holding up crucifixes...)
>
>JB
>
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