[vtk-developers] xxxxxSPAMxxxxx vtkBandedPolyDataContourFilter seems wrong, and also not compatable with vtkContourFilter

[Bill Lorensen]

Don't contour a vtkPolygon. The polygon contour algorithm first
triangluates the polygona and then contours the triangles. That's why
you get a strange bais in the contour lines.

If it is four sided, use a vtkQuad.

Try MarchingCubes (or ContourFilter)  with 12 levels and you'll get
the same contours as matlab.

There does seem to be a problem with the banded contour filter, Could
be some sort of edge affect.

Bill

On Tue, Jan 12, 2010 at 6:37 PM, Junjie Cao <jjcao1231 at gmail.com> wrote:
> Dear Sir,
>
> The vtkBandedPolyDataContourFilter seems wrong in some cases. I made an
> example to show this.
>
> 1.      vtkBandedPolyDataContourFilter output far worse than contourf of
> Matlab.
>
> 2.      The behavior of vtkBandedPolyDataContourFilter is quite different
> with vtkContourFilter.
>
> Is it a bug? How could I get a right result in VTK? The version of VTK used
> is 5.4.2, and that of ParaView is 3.6.2
>
> More details (test.pdf), all code and data (generated when you run plane.tcl
> or plane_contour.tcl.) for re-creating the test can be found
> inhttp://sites.google.com/site/jjcaoshomepage/faq-for-computer-graphics/probleminvtkbandedpolydatacontourfilter,
> since in the mail list "Message body is limited"
>
> Best wishes,
>
> JJCAO
>
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