[vtk-developers] The ImageStencil Issue
dgobbi at atamai.com
Tue Aug 22 18:46:41 EDT 2006
All of the regression test for the stencil are still passing. Do you
know what might be causing the code to fail?
dean.inglis at camris.ca wrote:
> Hi David,
> I find stencils extremely valuable! In fact,
> I have had to base most of my production code
> on a modified pre-executives VTK branch to keep
> my image region of interest pipelines functioning.
> I'm all in favor of any fixes/enhancements/expansions.
>> Hi All,
>> I'd like to redress some ugliness that I introduced to VTK a few years back.
>> The vtkImageStencilSource class requires the Spacing and Origin of
>> whichever image eventually uses the stencil to be propagated the wrong
>> way along the pipeline. Ouch!
>> Obviously the vtkImageStencilSource should actually take an Image as an
>> input and should then use that image to get the Spacing and Origin to
>> use for the stencil. This is a fairly minor change. For VTK 5.2, I can
>> then make VTK produce a deprecation warning if people don't set an input.
>> I would call the method SetInformationInput() to make it clear that only
>> the information (the Spacing, Origin, and WholeExtent) of the data would
>> be used. Also, vtkPolyDataToImageStencil() needs it SetInput() method
>> for the polydata input.
>> For example:
>> stencilSource = vtkImplicitFunctionToImageStencil()
>> histogram = vtkImageAccumulate()
>> Do people think this is a good change? Are there many people out there
>> who even use stencils in VTK? How many people know what a stencil is?
>> (Hint: it is an image mask stored in an efficient run-length format
>> instead of vtkImageData format).
>> Also, I'm not sure what the methods should be named in light of the VTK
>> 5 pipeline changes. Maybe I should name them as follows:
>> SetInformationInputConnection(vtkAlgorithmInput *) instead of
>> SetInformationInput(vtkImageData *)
>> SetStencilInputConnection(vtkAlgorithmInput *) instead of
>> SetStencil(vtkImageStencilData *)
>> I'd like to get this right, and I think that only small changes are
>> necessary to do so.
>> Also, of course, I'd like to see more of the filters in Imaging
>> utilizing stencils. Right now only a handful do (Blend, Reslice,
>> Stencil, Accumulate). The potential here is very high... a stencil
>> allows you to perform an operation only within a specified region of
>> interest, where the shape of the region can be whatever you desire. The
>> ROI can even be described by a vtkPolyData mesh or by a
>> vtkImplicitFunction, since these types can be converted efficiently into
>> - David
>> vtk-developers mailing list
>> vtk-developers at vtk.org
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