# How to project points to Polydata?

**URL:** https://discourse.vtk.org/t/how-to-project-points-to-polydata/5694
**Category:** Support
**Created:** [May 3, 2021, 11:31pm UTC](https://discourse.vtk.org/t/how-to-project-points-to-polydata/5694 "2021-05-03T23:31:39Z")
**Posts on this page:** 1
**Showing post:** 3

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### Author: ![scotsman60](https://discourse.vtk.org/user_avatar/discourse.vtk.org/scotsman60/32/6000_2.png) [@scotsman60](https://discourse.vtk.org/u/scotsman60)
#### Post date: [May 5, 2021, 6:53am UTC](https://discourse.vtk.org/t/how-to-project-points-to-polydata/5694/3 "2021-05-05T06:53:59Z")

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Thanks for the reply Will.  
In fact only part of this probem turned out to be the the target points not being close enough to the source cells - the real probelm is that the source cells in this case are polygons with more than four edges - and it appears that vtkProbeFilter just doesn’t support this cell topology.

 ![image](https://discourse.vtk.org/uploads/default/original/2X/6/690d53670ecd0591fd9a938fbc04957bbf21157a.png)

I partially solved the problem using vtkDataSetTriangleFilter to convert these cells to triangles,

 ![image](https://discourse.vtk.org/uploads/default/original/2X/2/2468992d033a2195b39607650e3a3444e9947d15.png)

But I’m still not fully happy with the result. (This is a validPointMask plot

 ![image](https://discourse.vtk.org/uploads/default/original/2X/a/a653a39ae7222b7f13b40286714f374ec0c7eb8c.jpeg)

The source and target are different meshes on the same cylndrical shape - so the deviation betwen the two is really quite small - basically proportional to the chord/arc sagitta. The cylinder diameter here is 130mm and the target mesh cell size is around 10mm

It gets better if I assign a 5mm tolerance (although I would have expected this to map EVERY point)

 ![image](https://discourse.vtk.org/uploads/default/original/2X/b/b542293368da0a8da7c5e98b2442acd706656d7c.png)

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