[vtkusers] Delaunay3D Unable to factor linear system?

[kenichiro yoshimi]

On 04/10/2010 04:54 PM, David Doria wrote:
> Can anyone explain why this code:
> http://www.vtk.org/Wiki/VTK/Examples/ConvexHull_vtkDelaunay3D_RealData
>
> Works on Input.vtp (a sphere with 50 points) , but not HardInput.vtp
> (a sphere with 290 points)
>
> (data available here http://www.rpi.edu/~doriad/VTK_List/Delaunay3D/)?
>
> I am getting "Unable to factor linear system" when I try it with HardInput.vtp.
>
> Thanks,
>
> David
>

This first warning occurs when inserting a tetra consiting of four points:
  ( 0.045706976205110550, 0.25921720266342163, -0.42510858178138733)
  (-0.045706998556852341, 0.25921720266342163, -0.42510858178138733)
  ( 0.031364466995000839, 0.17787675559520721, -0.46623611450195313)
  (-0.031364481896162033, 0.17787675559520721, -0.46623611450195313)
into existing Deluanay triangulates. However these points are
coplanar, that is a degenerate case. This warning means that a
circumsphere of this tetrahedron can't be determined uniquely.

In Paraview, I can see this degenarate tetra using "Collapse Ratio" of
"Tet Qulaility Measure" within "Mesh Quality Filter".

I'm sorry I don't know what to do about this problem.

yoshimi