# Calculating the circumference from cross sectional cut

**URL:** https://discourse.vtk.org/t/calculating-the-circumference-from-cross-sectional-cut/7793
**Category:** Support
**Created:** [February 8, 2022, 7:09am UTC](https://discourse.vtk.org/t/calculating-the-circumference-from-cross-sectional-cut/7793 "2022-02-08T07:09:00Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![dwventer](https://discourse.vtk.org/user_avatar/discourse.vtk.org/dwventer/32/1579_2.png) [@dwventer](https://discourse.vtk.org/u/dwventer)
#### Post date: [February 8, 2022, 7:09am UTC](https://discourse.vtk.org/t/calculating-the-circumference-from-cross-sectional-cut/7793/1 "2022-02-08T07:09:00Z")

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Hello, I’m using a vtkCutter to cut a cross-section from a poly data object using a vtkPlane as the cut function.

The result is a disc-like shape seen below:  
 ![image](https://discourse.vtk.org/uploads/default/original/2X/d/d2781ade15e80845eb38d00c890a2ea44dd44c7c.png)

I can use vtkMassProperties and get the surface area of this disc but how do I get the circumference?

Failing that, is there a way to only get the outer points of the object as there are points inside the objects that makes normal circumference calculations inaccurate.

Thanks

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### Author: ![Paulo\_Carvalho](https://discourse.vtk.org/user_avatar/discourse.vtk.org/paulo_carvalho/32/370_2.png) [@Paulo\_Carvalho](https://discourse.vtk.org/u/Paulo_Carvalho)
#### Post date: [February 8, 2022, 2:36pm UTC](https://discourse.vtk.org/t/calculating-the-circumference-from-cross-sectional-cut/7793/2 "2022-02-08T14:36:25Z")

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Hello,

Please, take a look at this: [How to extract the ids of the boundary points of a surface?](https://discourse.vtk.org/t/how-to-extract-the-ids-of-the-boundary-points-of-a-surface/2530)

It refers to an example that is no longer avaible, though a snapshot of it is available in The Wayback Machine: [https://web.archive.org/web/20200407105456/https://lorensen.github.io/VTKExamples/site/Cxx/Meshes/BoundaryEdges/](https://web.archive.org/web/20200407105456/https://lorensen.github.io/VTKExamples/site/Cxx/Meshes/BoundaryEdges/) .

regards,

Paulo

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### Author: ![dwventer](https://discourse.vtk.org/user_avatar/discourse.vtk.org/dwventer/32/1579_2.png) [@dwventer](https://discourse.vtk.org/u/dwventer)
#### Post date: [February 11, 2022, 4:13am UTC](https://discourse.vtk.org/t/calculating-the-circumference-from-cross-sectional-cut/7793/3 "2022-02-11T04:13:14Z")

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Thanks Paulo,

It seems that the problem was due to the Delaunay filter outputting unstructured data. When I filtered the output from the Delaunay filter through a Geometry filter it seemed to solve my problem.

Daniel