[vtkusers] Visualisation non linear cells

Soeren Gebbert soeren.gebbert at inpro.de
Thu Jan 13 10:40:09 EST 2005

Dear vtkusers and developers,
I'm using vtk 4.4 and paraview 1.8.2 at linux and windows. I'm a beginner
in vtk but i have some important questions to ask:

I want to add new nonlinear celltypes to vtk, like a quadratic quad with
an area center point and so on.
And i want to visualize them with a curved surface. Since now i used
paraview to visualize
the already implemented quadratic celltypes (QuadraticTetra ...). In
paraview i used the TempTessellatorFilter to get
a proper visualisation. I thought this filter is also implementet in vtk
but it isnt. So i searched for a
proper functionality in vtk to get my curved surface, but i didnt found
a filter.

As it is described in the vtk books, the quadratic cells will be
visualized as linear cells.
I guess the reimplemented function "Triangulate" from vtkCell in the in
the vtkNonLineareCell classes is doing this.
But there is a virtual function named Tesselate declrated in
vtkNonLinearCell, i guess this function will be used to render curved
surfaces, but this function is not implemented yet. So my question is:

1.) Is the function "Triangulate" responsible for the visualisation of
the different celltypes in vtk?
2.) If 1. is ture, can i reimplement the Triangulate function to create
curved surfaces for nonlineare cells?
3.) Is it possible to reimplement the "Tesselate" function and use this
for visualisation of nonlinear cells?
4.) If 1. - 3. is not true, what can i do to visualize 2D and 3D
nonlinear cells to get the form that is described
     in the shape function of these cells?

Thanks alot and best regards
Soeren Gebbert

Please excuse my english.

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