# How to select cells on the outermost layer given a vector?

**URL:** https://discourse.vtk.org/t/how-to-select-cells-on-the-outermost-layer-given-a-vector/7880
**Category:** Support
**Created:** [February 19, 2022, 4:52am UTC](https://discourse.vtk.org/t/how-to-select-cells-on-the-outermost-layer-given-a-vector/7880 "2022-02-19T04:52:31Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![Cameron](https://discourse.vtk.org/user_avatar/discourse.vtk.org/cameron/32/4063_2.png) [@Cameron](https://discourse.vtk.org/u/Cameron)
#### Post date: [February 19, 2022, 4:52am UTC](https://discourse.vtk.org/t/how-to-select-cells-on-the-outermost-layer-given-a-vector/7880/1 "2022-02-19T04:52:31Z")

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Hi VTK community,

I have a unstructured data (see the following) where I need to select the cells which are the outermost layer by the projection of a given vector N.

 ![image](https://discourse.vtk.org/uploads/default/original/2X/c/cfcc399b5da7a473568ac9e83f4a62caa6a65a08.png)  
I am currently looking into vtkHardwareSelect and vtkCellLocator. I wonder if there is already an API to do this kind of thing?  
What I eventually need to do is to perform it recursively until there is no cell left.

Thanks,  
Cam