# create tetrahedral from a set of points using vtkDelaunay3D
**URL:** https://discourse.vtk.org/t/create-tetrahedral-from-a-set-of-points-using-vtkdelaunay3d/938
**Category:** Support
**Created:** [May 9, 2019, 8:54pm UTC](https://discourse.vtk.org/t/create-tetrahedral-from-a-set-of-points-using-vtkdelaunay3d/938 "2019-05-09T20:54:42Z")
**Posts on this page:** 5
**Page:** 1
### Author:  [@Ida](https://discourse.vtk.org/u/Ida)
#### Post date: [May 9, 2019, 8:54pm UTC](https://discourse.vtk.org/t/create-tetrahedral-from-a-set-of-points-using-vtkdelaunay3d/938/1 "2019-05-09T20:54:42Z")
Hi,
How do I create tetrahedral from a set of points using vtkDelaunay3D? This is what I have come up with so far.
vtkDelaunay3D\* getDelaunayTets; // create instance of vtkDelaunay3D
vtkPoints\* points;
points=vtkPoints::New(); // initialise points (online example - not clear from doc)
points-\>InsertNextPoint(0,0,1); // insert points (online example - not sure if points r added)
points-\>InsertNextPoint(0,0,0);
points-\>InsertNextPoint(0,1,0);
points-\>InsertNextPoint(1,0,0);
points-\>InsertNextPoint(0.5,0.5,0.5);
vtkUnstructuredGrid\* Mesh; vtkIdType id; double x[3]; vtkIdList\* holeTetras;
getDelaunayTets-\>InsertPoint(Mesh, points, id, x, holeTetras);
I get an initialisation error for holeTetras and I am not sure how to initialise holeTetras.
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### Author:  [@lassoan](https://discourse.vtk.org/u/lassoan)
#### Post date: [May 9, 2019, 11:04pm UTC](https://discourse.vtk.org/t/create-tetrahedral-from-a-set-of-points-using-vtkdelaunay3d/938/2 "2019-05-09T23:04:58Z")
First you need to create a point set, then set it at input to the Delaunay filter, execute the filter, then retrieve the unstructured grid output.
Read the VTK textbook and check out related VTK examples.
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### Author:  [@Ida](https://discourse.vtk.org/u/Ida)
#### Post date: [May 11, 2019, 3:10pm UTC](https://discourse.vtk.org/t/create-tetrahedral-from-a-set-of-points-using-vtkdelaunay3d/938/3 "2019-05-11T15:10:05Z")
Thank you the suggestions.
If I understand your steps correctly, I need to create points, pass the points to Delaunay and execute a function within Delaunay that returns the mesh.
I have had a look at the vtkDelaunay3D cxx example which reads in points from a file and uses the SetInputConnection function to pass outputs of a filter as input to another filter. What remains unclear to me is how to pass a vtkPointSet (or vtkPoint, used by me) to vtkDelaunay3D. Could you kindly help with this? My c++ skills are still under development. Thanks.
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### Author:  [@lassoan](https://discourse.vtk.org/u/lassoan)
#### Post date: [May 11, 2019, 8:06pm UTC](https://discourse.vtk.org/t/create-tetrahedral-from-a-set-of-points-using-vtkdelaunay3d/938/4 "2019-05-11T20:06:27Z")
> [@Ida](#):
>
> What remains unclear to me is how to pass a vtkPointSet (or vtkPoint, used by me) to vtkDelaunay3D
It is shown in hundreds of examples how to set input connection or input data in a filter. There is even an [example specifically for using Delaunay3D filter](https://lorensen.github.io/VTKExamples/site/Cxx/Modelling/Delaunay3D/).
Please spend some time reading the freely available [VTK textbook](https://lorensen.github.io/VTKExamples/site/VTKBook/) and [VTK examples](https://lorensen.github.io/VTKExamples/site/).
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### Author:  [@Ida](https://discourse.vtk.org/u/Ida)
#### Post date: [May 12, 2019, 10:10am UTC](https://discourse.vtk.org/t/create-tetrahedral-from-a-set-of-points-using-vtkdelaunay3d/938/5 "2019-05-12T10:10:11Z")
Thank you for your responses; they are much appreciated.