[vtk-developers] RE: Problem when creating vtkImageData by hand
Brad King
brad.king at kitware.com
Fri Aug 12 20:58:53 EDT 2005
Prabhu Ramachandran wrote:
>>>>>>"Dean" == Dean Inglis <dean.inglis at camris.ca> writes:
>
>
> Dean> and removed the outline filter from the pipeline and
> Dean> everything runs fine. As soon as I add the outline filter,
> Dean> I get the same weird results. I haven't figured out if this
> Dean> is a pipeline problem, IPW problem or outline filter
> Dean> pb.... :{
>
> Thanks for the confirmation of the problem! This means there is a
> nasty bug lurking somewhere in there.
I've found the problem. The vtkOutlineFilter derives from
vtkPolyDataAlgorithm. vtkPolyDataAlgorithm::RequestUpdateExtent sets
RequestExactExtent to 1 so that it requests the exact unstructured
extent. However when the input of vtkOutlineFilter is a structured data
set this may not be what we want. When the input to the outline filter
is from the reader then it can produce the exact extent for each update
without losing anything. When the input to the outline filter is a
stand-alone data object it is given a vtkTrivialProducer.
Since vtkTrivialProducer has only one copy of the data it will never
actually generate or re-initialize its output. However when
RequestExactExtent is on then the executive crops the data and it is
lost forever!
The reason this did not happen in VTK 4.4 is that vtkOutlineFilter did
not set RequestExactExtent. If I add a RequestUpdateExtent method to
vtkOutlineFilter and change RequestExactExtent back to 0 then the
problem is fixed. I'm not sure this is the correct solution though. Ken?
Comments?
-Brad
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