[vtk-developers] potential speedup for the vtkpolydatatoimagestencil

[David Gobbi]

There is a dashboard test that uses the direct path (see the section
after "#test again with a contour").  It only uses a single contour,
but I've used vtkPolyDataToImageStencil extensively with a series
of contours.  The example passes the contours through vtkStripper
to make each contour into an ordered, contiguous polyline but I don't
think that step is necessary.

http://vtk.org/gitweb?p=VTK.git;a=blob;f=Hybrid/Testing/Tcl/TestImageStencilWithPolydata.tcl;#l35

 - David

On Mon, Feb 27, 2012 at 2:07 PM, Mark Roden <mmroden at gmail.com> wrote:
> Hi David,
>
> I know where the split in the code is.  My point is that the direct
> path doesn't work with rtstructs, ie, the result of reading rtstructs
> via the vtkGDCMPolyDataReader.  It only works if I run the extrusion
> first.  In addition, I can't find other code that uses the direct
> path, so I can't see how to fix the polydata (if it's, in fact,
> broken) to use the direct path.
>
> So how can I get the direct path to be chosen?  The output from the
> reader is a set of lines, and only adds polys once we do the
> extrusion.  Given that it still takes 10 seconds, _something_ is being
> done there...
>
> Thanks,
> Mark
>
> On Mon, Feb 27, 2012 at 12:58 PM, David Gobbi <david.gobbi at gmail.com> wrote:
>> On Mon, Feb 27, 2012 at 1:24 PM, Mark Roden <mmroden at gmail.com> wrote:
>>
>>> David, if you could please shed some light on how to use the faster code path-- right now, it produces blank binary images.
>>
>> See line 320 in the source code.  That's the "if" statement that
>> chooses the cutter-path (if the input is polys) or the direct path (if
>> the input is polyline contours that are aligned with the slices).
>>
>> http://vtk.org/gitweb?p=VTK.git;a=blob;f=Hybrid/vtkPolyDataToImageStencil.cxx;#l320
>>
>> If you want to be sure about what path your data is taking, you can
>> add print statements to the code, or run your program in a debugger.
>>
>>  - David