[vtkusers] How to extract area of (triangle) Cells?

[lynx.abraxas at freenet.de]

Hello!


I'd  need  to  get the area of the cells (triangle) to weight the cell normals
(as discussed in the thread below).
My research on this lead me to http://www.cmake.org/Wiki/VTK_Examples where it
says that CellData needs an associated data (eg. area of triangle). Would that
be GetCellData().GetScalars()? Or would I need to apply a  filter  first  that
actually calculates the cell area or would I have to do that my self?
I also found this example:
http://www.cmake.org/Wiki/Add_Miscellaneous_Data_to_Cells_in_a_Polydata
but the area there seems to me very arbritrary;-)

Thanks for any help or hints.
Lynx



On 18/11/09 20:50:13, renlishen wrote:
> 
> I have seen the post "How to extract the average normal from
> vtkPolyDataNormals",
> and I try to do the same thing
> ------------------------------------------------------
> 	vtkPolyDataNormals *triangleCellNormals = vtkPolyDataNormals::New() ;
> 	triangleCellNormals->SetInput(
> triangleCellDataSetSurfaceFilter->GetOutput() ) ;
> 	triangleCellNormals->ComputeCellNormalsOff() ;
> 	triangleCellNormals->ComputePointNormalsOn() ;
> 	triangleCellNormals->ConsistencyOn() ;
> 	triangleCellNormals->AutoOrientNormalsOn() ;
> 	triangleCellNormals->Update() ;
> 
> 	vtkFloatArray *PointNormalArray = vtkFloatArray::SafeDownCast(
> triangleCellNormals->GetOutput()->GetCellData()->GetNormals() ) ;
> -------------------------------------------------------
> My question is ..I can't connect GetCellData() to GetNormals().. 
> If the method is wrong, how can I do to get normals?
> 
> I can display, but my goal is to get points' normal....
> p.s. I am using VTK5.4.2...
> 
> thanks for your help~!!
> http://old.nabble.com/file/p26420378/1.png 
> -- 
> View this message in context: http://old.nabble.com/About-vtkPolyDataNormals....-tp26420378p26420378.html
> Sent from the VTK - Users mailing list archive at Nabble.com.
> 
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