# [Paraview] Clever way to identify a ring of element?

kenichiro yoshimi rccm.kyoshimi at gmail.com
Tue Jun 20 07:50:16 EDT 2017

Hello Dennis,

To apply the slice filter to a doughnut polygon creates line segments
obtained by intersecting it with section planes. And then to apply the
connectivity filter to the result gives curve rings consisting of
consecutive line segments and each of rings is assigned a RegionId.
You can try the attached Status file with ParaView 5.4.

Unfortunately these elements belonging to the rings are in Cartesian
coordinate system. So, you need to convert the elements' coordinates
from Cartesian (x,y,z) to Cylindrical (r,\theta,z). At that time, the
following code would be helpful to compute a barycenter and a mean
https://github.com/vmtk/vmtk/blob/master/vtkVmtk/ComputationalGeometry/vtkvmtkBoundaryReferenceSystems.cxx

Thanks,
yoshimi

2017-06-16 1:58 GMT+09:00 Dennis Conklin <dennis_conklin at goodyear.com>:
> All,
>
>
>
> Imagine I have a model of a doughnut.   I want to identify rings in the
> model.   A ring is a set of elements in an r, z, theta coordinate system
> which has the same radius and z_coordinate and only differs in the angular
> coordinate.  Of course, since trig functions are used  in calculating the
> radius, we are not guaranteed that the radius will be absolutely identical
> for each element in the ring.
>
>
>
> Is there a clever (as in fast and easy) way to sort out elements belonging
> to individual rings and perhaps assign something like a ring number to them
> so that a threshold could be used to examine individual rings.   I’m hoping
> there is some clever vtk stuff that I’m not familiar with that would help
> with this.
>
>
>
> Thanks for any thoughts
>
>
>
> Dennis
>
>
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