[vtkusers] RE: FW: [Paraview] Cutting cells of different dime nsion

[ALIZIER Julien AUSY]

Salut Mathieu,

I didn't use any pipeline, I just made a .vtk file with no point data at all
(see the file at the end of my first email). But in paraview, it's possible
to do it using the PointDataToCellData filter with the option "Pass Point
data" unchecked.

I am not using the quadratic cells (I tried but I had polygons going away)
and actually I didn't want to contour a cell, I just wanted to cut it! I
think too that it is a non-sense to contour a cell that has scalar value
defined on the whole cell.
But I saw in the source code that the vtkCutter uses a trick to cut cells:
it assigns values to vertices and asks the cell to contour according to
these values.

-- Julien



-----Message d'origine-----
De : Mathieu Malaterre [mailto:mathieu.malaterre at kitware.com]
Envoyé : jeudi 12 février 2004 16:52
À : ALIZIER Julien AUSY
Cc : 'vtkusers at vtk.org'
Objet : Re: [vtkusers] RE: FW: [Paraview] Cutting cells of different
dimension


Salut Julien,

	Just for curiosity. Waht is the pipeline you use to get cell scalars

(but no points scalars). BTW the quadratic cells in VTK are by design 
not meant to use cell scalars but point scalars and actually do 
interpolation. Just think of this: how do you contour a cell that has 
the same scalar value for every cell ?

Thanks
Mathieu

ALIZIER Julien AUSY wrote:
> Thanks for your reply.
> For your information, I tried vtkKitwareCutter instead of vtkCutter and it
> had the same problem. 
> 
> -- Julien
> 
> 
> 
> -----Message d'origine-----
> De : Amy Henderson [mailto:amy.henderson at kitware.com]
> Envoyé : mercredi 11 février 2004 19:17
> À : ALIZIER Julien AUSY; 'paraview at paraview.org'; 'vtkusers at vtk.org'
> Objet : Re: FW: [Paraview] Cutting cells of different dimension
> 
> 
> Hi Julien,
> 
> The problem is in cell->Contour(...) (or maybe in the way vtkCutter is 
> using cell->Contour(...)).  What's happening is that when the cell
contours 
> itself, it adds a new cell as necessary to the appropriate cell array 
> (verts, lines, or polys), which returns the id of the cell in that array. 
> Contour then uses that id to copy cell data to.  The problem is that if 
> your data set has different types of cells, then the first vertex, line, 
> and polygon inserted will all have the same cell id.  I'll add this as a 
> bug report for VTK.
> 
> - Amy
> 
> At 10:25 AM 2/11/2004, ALIZIER Julien AUSY wrote:
> 
>>And it does work if I use POINT_DATA instead of CELL_DATA.
>>Any ideas? I this a bug in vtkCutter or cell->Contour(...)?
>>
>>-- Julien
>>
>>
>>
>>-----Message d'origine-----
>>De : ALIZIER Julien AUSY [mailto:julien.alizier-ausy at irsn.fr]
>>Envoyé : mercredi 11 février 2004 16:17
>>À : 'paraview at paraview.org'; 'vtkusers at vtk.org'
>>Objet : [Paraview] Cutting cells of different dimension
>>
>>
>>Hi all,
>>
>>I am trying to make a cut of 3D and 2D cells in one Unstructured grid in
>>ParaView.
>>The problem is that it is possible to cut only if there is no data on
cells
>>(which is not very useful obviously ;-).
>>
>>Here is a tiny vtk file that shows the bug : it is a triangle and a line
> 
> and
> 
>>I'd like to cut them in order to get a line and a point. It works when I
>>removed the CELL_DATA part.
>>
>>Thanks for your help
>>
>>-- Julien
>>
>>
>># vtk DataFile Version 2.0
>>cut problem with cell of different dimension
>>ASCII
>>DATASET UNSTRUCTURED_GRID
>>POINTS 5 float
>>0 0 0
>>2 0 2
>>1 3 1
>>4 0 4
>>4 3 4
>>
>>CELLS 2 7
>>3 0 1 2
>>2 3 4
>>
>>CELL_TYPES 2
>>5
>>3
>>
>>CELL_DATA 2
>>SCALARS cell_scalars float 1
>>LOOKUP_TABLE default
>>0
>>1
>>_______________________________________________
>>ParaView mailing list
>>ParaView at paraview.org
>>http://www.paraview.org/mailman/listinfo/paraview
> 
> 
> 
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