[vtk-developers] Pyramid and QuadraticPyramid formulation issues

[Will Schroeder]

Bill it could be that the vtkPyramid functions were originally written (a
long time ago) as degenerate hex shape functions which might explain the
apex parametric coordinates. I believe Mathieu found and implemented an
alternative formulation and also added the quadratic version; I'm not sure
where to find that reference.
W

On Sat, Jun 20, 2015 at 2:31 PM, Bill Lorensen <bill.lorensen at gmail.com>
wrote:

> Folks,
>
> As I continue to work through a comprehensive unit test for vtk cells,
> I have found an issue(s) with vtkPyramid and vtkQuadraticPyramid.
>
> For example, the parametric coordinates for the Pyramid (and Quadratic
> Pyramid) place the apex at 0, 0, 1. I believe it should be centered on
> the base (which would be .5, .5, 1).
>
> Changing that causes other issues with the shape functions.
>
> I am seeking a copy of the reference quoted in the QuadraticPyramid
> code so that I can verify the implementation.
> // The shape functions and derivatives could be implemented thanks to
> // the report Pyramid Solid Elements Linear and Quadratic Iso-P Models
> // From Center For Aerospace Structures
>



-- 
William J. Schroeder, PhD
Kitware, Inc.
28 Corporate Drive
Clifton Park, NY 12065
will.schroeder at kitware.com
http://www.kitware.com
(518) 881-4902
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