[vtkusers] Re: Getting pixel values

[David Gobbi]

On Tue, 3 Jul 2001, Dave Reed wrote:

> David Gobbi wrote:
>
> > I'm currently working on a vtkImageStencilFilter to allow segmentation
> > of an image using an existing vtkImplicitFunction or closed
> > vtkPolyData surface (hopefully it will be committed this week).
>
> That's what I'd eventually like to do - add the capability to
> semi-automatically segment with polylines or curves. Please let me/us
> know when you're done.

I committed the changes to CVS yesterday (they're functional, but not
finished).  You can take a look at contrib/examplesTcl/TestPolyStencil.tcl
and imaging/examplesTcl/TestStencil.tcl.  To segment with a polyline, you
will have to use vtkLinearExtrusionFilter to turn it into a surface
before you can segment with it.

My plan is to eventually add a new data type 'vtkImageStencilData' that
describes a stencil and to have filters to convert vtkImplicitFunctions
and vtkPolyData (surfaces for now, perhaps lines later) into
vtkImageStencilData.  The vtkImageStencilData will be used by
vtkImageStencil to perform cookie-cutter operations on images,
and possibly by vtkImageAccumulate to perform histogram operations on
cut-out portions of an image.  The changes I committed last night
are the first step.

And just in case anyone is wondering why I need a new data type
to describe the stencil and why I don't just use a binary image,
efficiency (and perhaps novelty) is about the only reason I can give.

 - David