[vtkusers] problem computing the volume of a tetrahedral cell

[Francois Bertel]

The implementation of ComputeVolume uses a determinant, not surrounded
by an absolute value. I guess the volume is signed depending on the
orientation of the points of the tetra (positive for a right-handed
tetra and negative for a left-handed tetra).

I don't know if it is an expected behavior or not.

Anyway, It may mean in your case that the output of
vtkDataSetTriangleFilter does not produce right-handed tetra. Maybe
because the input itself has bad oriented hexahedra.

I'm just guessing. Maybe somebody else has a better answer.

Vines, John (Civ, ARL/CISD) wrote:
> All,
> I am trying to compute the volume of a tetrahedral cell using the "vtkTetra::ComputVolume()" method.  I do not understand why I am getting negative values?
>  
> At present I am converting hexahedral cells to tets using the vtkDataSetTriangleFilter().  I then feed in the points from each tetrahedral cell to the vtkTetra::ComputeVolume() method.
>  
> Any help is greatly appreciated, thanks for your time
>  
> John Vines
> Army Research Laboratory
> Scientific Visualization Team

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