[Paraview] Normal vector to Exodus Sideset elements

[Moreland, Kenneth]

Dennis,

Yes, this cat has a zipper that allows it's skin to come right off. (Maybe I took that "skin the cat" metaphor a bit too far.)

Anyway, just run the Extract Surface filter. After that you can run the Generate Surface Normals filter.

-Ken

From: ParaView [mailto:paraview-bounces at public.kitware.com] On Behalf Of Dennis Conklin
Sent: Monday, April 9, 2018 1:22 PM
To: Paraview (paraview at paraview.org) <paraview at paraview.org>
Subject: [EXTERNAL] [Paraview] Normal vector to Exodus Sideset elements

All,

I'm sure I'm missing something here, so please knock me up alongside the head and point it out.

I load a sideset (surface) from an Exodus file.   I end up with a bunch of quads that Paraview conveniently created for me from the surface.   I need to calculate a Normal vector for each of these quads.  I have tried:

Generate surface normal - this is greyed out (wants poly data?)

Delaunay 3D on this to generate poly data, which I could then hopefully run Generate surface normal on, but it was still greyed

Tried Normal Glyphs which gave me point Normal vectors but gave me a bunch of Triangle and Polygon elements - I'm not sure what's going on here.
    PointDataToCellData to get GlyphVector for each Cell
    Python Calculator and ask for area(inputs[0]) the Polygon elements all get an Area of -1
    Calculator to get Area_X as product of GlyphVector_X and Area
    Threshold on Area_X > 0 -  don't want negative areas or some boundary cells with GlyphVector_X as negative
    Python Calculator to get sum(Area_X)
    This number appears to be about half of my expected number

These must be an easier way.  I'm not a vtk guru.   When I first load my surface, is there some vtk routine I could call within a Programmable filter to get the cell normal?????

Alternatively, anyone got an easier way to skin this cat?

Thanks for any hints  you may have.

Dennis

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