Point ordering for vtkLagrangeHexahedron?

I’m interested in using vtkLagrangeHexahedrons for my app (a spectral element simulation). I’ve written a simple example, but the surfaces look funky.

This is a 3rd order hex, and it’s labeled with the vertex IDs. I’ve set them up according to the diagrams from this blog post.

Is there a problem with my point ordering? Or do you expect surfaces to look like this for the Lagrange hexes?


BTW, a comment in the ParaView forum said there were some mistakes in the KitWare blog post, but I can’t seem to track down the corrections.

I did some inspection and experimentation, and I found that I could get the expected cells by swapping:

  • Face 40 <–> Face 32
  • Face 44 <–> Face 36
  • Edge (30,31) <–> Edge (28, 29)

Those numberings are based on the diagrams in the blog post.

With these swaps, it seems to make the ordering rules more consistent with the blog post’s text description. I’d still appreciate some verification, though! :slight_smile: