# How to extract the ids of the boundary points of a surface?

**URL:** https://discourse.vtk.org/t/how-to-extract-the-ids-of-the-boundary-points-of-a-surface/2530
**Category:** Support
**Created:** [February 1, 2020, 2:30am UTC](https://discourse.vtk.org/t/how-to-extract-the-ids-of-the-boundary-points-of-a-surface/2530 "2020-02-01T02:30:34Z")
**Posts on this page:** 1
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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 1, 2020, 5:38pm UTC](https://discourse.vtk.org/t/how-to-extract-the-ids-of-the-boundary-points-of-a-surface/2530/2 "2020-02-01T17:38:35Z")

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My first attempt would be to assign the id’s to a scalar field (to the vertexes) in the original mesh as `vtkFeatureEdges` is supposed to preserve scalars in the output. This would be a little less awkward, IMO, than performing a spatial search.

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