[vtkusers] vtkhexahedron gaussian points

[John Platt]

Hi Dean,

Extrapolate the scalars from the quadrature points to the nodes then
average. To extrapolate, transform the quadrature points to (0,1) (VTK
parametric space). Calculate the parametric coordinates of the nodal
points using the same transformation and use as pcoords[] in the
interpolation functions (from memory (1 +/- sqrt(2))/2). You should also
check that it makes physical sense to average nodal values across cells.


In FE, the optimal sampling points for certain results do not coincide
with the nodes. Furthermore, discontinuities prevent nodal averaging. It
would be very useful to have vtkPointCellData which stores point values
on a per cell basis.

HTH

John.

-----Original Message-----
From: vtkusers-bounces+jcplatt=lineone.net at vtk.org
[mailto:vtkusers-bounces+jcplatt=lineone.net at vtk.org] On Behalf Of Dean
Inglis
Sent: 20 October 2005 18:10
To: vtkusers archive
Subject: [vtkusers] vtkhexahedron gaussian points

Is there a way to directly visualize scalar fields
located at the 8 quadrature points of a hexahedral
3D element? or, do I need to average nearest neighbor
values to nodes and then visualize the data at the
nodal points?

Dean

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