[vtk-developers] RE: Problem when creating vtkImageData by hand

[Prabhu Ramachandran]

>>>>> "Brad" == Brad King <brad.king at kitware.com> writes:

    Brad> 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.

    Brad> I've found the problem.  The vtkOutlineFilter derives from
    Brad> vtkPolyDataAlgorithm.
    Brad> vtkPolyDataAlgorithm::RequestUpdateExtent sets
    Brad> RequestExactExtent to 1 so that it requests the exact
    Brad> unstructured extent.  However when the input of
[...]
    Brad> Since vtkTrivialProducer has only one copy of the data it
    Brad> will never actually generate or re-initialize its output.
    Brad> However when RequestExactExtent is on then the executive
    Brad> crops the data and it is lost forever!

I don't understand this.  Shouldn't this work because the pipeline is
"branched" in the sense that the resliced output is used by one actor
and the original (intact) data is used by the outline filter.  Why
should the cropping propagate upstream at all and affect all branches
of the pipeline?

cheers,
prabhu