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OCC exception. LProp_NotDefined

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OCC exception. LProp_NotDefined

Posted by Pedro Aznárez at May 27. 2020

Hi,

I'm having this error, about which I found no documentation. It occurs on certain files some of my engineers are exporting. I'm doing 2D meshes with Netgen 2D-1D, using the same hypothesis which worked flawlessly on other parts. The hypothesis being

Max: 10

Min: 0.1

Grow Rate: 0.8

Chordal Error: 0.1

No optimization

This is my test hypothesis before refining the mesh. Some files are pure surfaces, some others are solids. The outcome (for the good or the bad) seems independent of that. I couldn't upload some of the conflicting parts to illustrate due to size.

Thank you very much for any insight into this issue.

Best Regards!

Re: OCC exception. LProp_NotDefined

Posted by SMESH expert at May 27. 2020

Hello!

I suspect that your geometry includes a face with a singular point, like a sphere pole, where normal to face is undefined. NETGEN makes some checks to deal with such points, but these checks are not safe enough IMHO. Probably exactly in your case these checks do not work as expected. I mean the checks in OCCSurface::GetNormalVector() (libsrc/occ/occmeshsurf.cpp:49)

To cope with this you can try to identify that "difficult" face and reconstruct it so that it had no pole.

Best regards

Edward

Re: OCC exception. LProp_NotDefined

Posted by Pedro Aznárez at May 27. 2020

I have isolated the conflicting surface by Explode->Faces in the Geometry Module, and was able to mesh the face without issues. Even more, if I suppress that face, the error appears in the next-to-it face, and so on. But every face is meshable on it's own. I also tried Sewing and Gluing, but such algorithms detect nothing to do.

Best Regards,

Previously SMESH expert wrote:

Hello!

I suspect that your geometry includes a face with a singular point, like a sphere pole, where normal to face is undefined. NETGEN makes some checks to deal with such points, but these checks are not safe enough IMHO. Probably exactly in your case these checks do not work as expected. I mean the checks in OCCSurface::GetNormalVector() (libsrc/occ/occmeshsurf.cpp:49)

To cope with this you can try to identify that "difficult" face and reconstruct it so that it had no pole.

Best regards

Edward

 

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