# Get the profile/shape/outline of several polygons

**URL:** https://discourse.paraview.org/t/get-the-profile-shape-outline-of-several-polygons/11599
**Category:** ParaView Support
**Tags:** vtk
**Created:** [March 9, 2023, 9:26am UTC](https://discourse.paraview.org/t/get-the-profile-shape-outline-of-several-polygons/11599 "2023-03-09T09:26:53Z")
**Posts on this page:** 3
**Page:** 1

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### Author: ![Marek-Muchow](https://discourse.paraview.org/user_avatar/discourse.paraview.org/marek-muchow/32/11122_2.png) [@Marek-Muchow](https://discourse.paraview.org/u/Marek-Muchow)
#### Post date: [March 9, 2023, 9:26am UTC](https://discourse.paraview.org/t/get-the-profile-shape-outline-of-several-polygons/11599/1 "2023-03-09T09:26:53Z")

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Hi,

I have 3D polygonal vtk data, which I want to reduce to 2D and then get the outline/profile of that shape. The latter is what I struggle to archive.

My best bet yet is use the Calculator (`Coordinate Results` and use the expression `coordsX*iHat + coordsY*jHat` according to this [stackoverflow suggestion](https://stackoverflow.com/questions/45544709/paraview-view-a-2d-projection-of-a-3d-object)). Then I used the `Feature Edges` filter as suggested, but then I see all edges stacked on top of each other (see picture below) and I don’t know how to proceed from here to get only the “outer most” edge.

Additionally, I found [this forum post](https://discourse.paraview.org/t/feature-external-edges-only/2812) here, which suggests to use `Extract Surface`. This does not really change my result (and running `Clean To Grid` does result in me being not allowed to apply filters anymore).

Solutions involving the paraview software would be appreciated the most, but if there are solutions which involve switching to some python modules for vtk data, that can also work.

 ![Example_Picture](https://discourse.paraview.org/uploads/default/original/2X/d/d92f71d131391cd81f543d07b266c98797e068e0.png)

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### Author: ![Francois\_Mazen](https://discourse.paraview.org/user_avatar/discourse.paraview.org/francois_mazen/32/6483_2.png) [@Francois\_Mazen](https://discourse.paraview.org/u/Francois_Mazen)
#### Post date: [March 9, 2023, 1:18pm UTC](https://discourse.paraview.org/t/get-the-profile-shape-outline-of-several-polygons/11599/2 "2023-03-09T13:18:18Z")

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Hi @Marek-Muchow !

Have you tried Delaunay 2D filter after the 2D projection? Then using the connectivity filter and feature edges extraction may give the expected result.

Best,

François

@Charles_Gueunet

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### Author: ![Marek-Muchow](https://discourse.paraview.org/user_avatar/discourse.paraview.org/marek-muchow/32/11122_2.png) [@Marek-Muchow](https://discourse.paraview.org/u/Marek-Muchow)
#### Post date: [March 13, 2023, 9:44am UTC](https://discourse.paraview.org/t/get-the-profile-shape-outline-of-several-polygons/11599/3 "2023-03-13T09:44:04Z")

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Thanks @Francois_Mazen - that helped a lot. I just have one question left.

To archive the result in the picture I applied the calculator (as given above), then the Delauny2D filter and then the Feature Edges, with only the Boundary Edges turned on.

I was now wondering if there is a way to refine the Boundary Edges? As seen below, there is sometimes quite the gap between the outline and the 2D shape.

 ![Outline](https://discourse.paraview.org/uploads/default/original/2X/e/e7d59bcc8c77d4fa75ac776c24a80b864706449e.png)  
The result from the calculator is in red, the results of the Delaunay 2D are the black points and the outline of the Feature Edges is in pink.