# vtkGeometryFilter and its evil spawn vtkDataSetSurfaceFilter

**URL:** https://discourse.vtk.org/t/vtkgeometryfilter-and-its-evil-spawn-vtkdatasetsurfacefilter/4083
**Category:** Development
**Created:** [August 27, 2020, 10:34am UTC](https://discourse.vtk.org/t/vtkgeometryfilter-and-its-evil-spawn-vtkdatasetsurfacefilter/4083 "2020-08-27T10:34:20Z")
**Posts on this page:** 1
**Showing post:** 4

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### Author: ![Martin3d](https://discourse.vtk.org/user_avatar/discourse.vtk.org/martin3d/32/4303_2.png) [@Martin3d](https://discourse.vtk.org/u/Martin3d)
#### Post date: [September 28, 2021, 4:15pm UTC](https://discourse.vtk.org/t/vtkgeometryfilter-and-its-evil-spawn-vtkdatasetsurfacefilter/4083/4 "2021-09-28T16:15:54Z")

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I found that the file I am using has **repeated vertices**. The cubes of my shape share no point with other cubes. As vtkGeometryFilter works with point IDs and not with the underlying point coordinates, it can not filter anything 🙂

I haven’t found yet a way to tell VTK to merge repeated points in a dataset. I will confirm the above as soon as I find a way to do so.

Applying vtkGeometryFilter on a collection of hexahedron having **shared vertices** works.

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_[View the full topic](https://discourse.vtk.org/t/vtkgeometryfilter-and-its-evil-spawn-vtkdatasetsurfacefilter/4083)._