[vtkusers] Merging of points

[James Robinson]

Dear All,

 

I am creating an instance of 

  vtkCutter         *pCrossSection ; from vtkUnstructuredGridReader
*pMeshReader

and   

vtkClipPolyData   *pXSectionClipper ; from vtkGeometryFilter
*pGeometry ;

 

and merging them into

  vtkAppendPolyData *pCutMeshData ;

 

The problem is that, when I do a colour plot of the scalar I get a bad
effect at an internal boundary (where the boundary is formed by having
coincident "nodes" in a finite element mesh that are in congruent elements -
this forms a no flow boundary in the mesh). The rendering of the colour
contouring works perfectly when the vtkUnstructuredGrid is put through the
vtkGeometryFilter, but the coincident nodes are merged (I think) when the
mesh is cut (using the object listed above) and the colour mapping is fuzzy
along the boundary (whereas it should be a sheer change in colour).

 

My questions are:

would merging explain the phenomenon described above?

is there a way to turn off point merging in vtkCutter & vtkClipPolyData?

 

Regards,

 

Jim  

James C Robinson, PhD, Chartered Engineer,

*     42 Rivergrove,

         Glanmire,

         Co. Cork,

         Eire

'     +353 21 4822028

         +353 87 2393010

6      +353 21 4822028

*    j.robinson at kepler-systems.com 

 

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