[vtk-developers] The ImageStencil Issue
dgobbi at atamai.com
Wed Aug 23 12:19:53 EDT 2006
Am I allowed to object? (Just kidding!).
The changes are only a few hours work, Kitware already did most of the
work and only a few touch-ups remain.
After the changes, people will have to call
SetInformationInputConnection() on whichever vtkImageStencilDataSource
they use so there will be some deprecation.
David Cole wrote:
> I'd like to rephrase the main question of this discussion:
> Would anybody object to David Gobbi making stencils use the new
> pipeline properly?
> And would anybody object to those changes being propagated into the
> VTK-5-0 branch if possible?
> David Gobbi,
> Would it be a lot of work to make stencils use the new pipeline properly?
> Do you foresee any difficulty merging those changes into VTK-5-0...?
> I'm all for you making these changes: conforming to the new pipeline
> is good in general and you are obviously the man for this particular job.
> If you're going to redress ugliness, you may as well redress it in the
> 5.0 branch, too... I'd be happy to help with merging the changes into
> the 5.0 branch after you commit them to CVS HEAD.
> David Cole
> David Gobbi wrote:
>> 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 vtkImageStencilData.
>> - David
>> vtk-developers mailing list
>> vtk-developers at vtk.org
More information about the vtk-developers