# vtk Delaunay2D is too expensive, how can i accelerate
**URL:** https://discourse.vtk.org/t/vtk-delaunay2d-is-too-expensive-how-can-i-accelerate/8887
**Category:** Dashboards
**Tags:** code
**Created:** [July 6, 2022, 10:26am UTC](https://discourse.vtk.org/t/vtk-delaunay2d-is-too-expensive-how-can-i-accelerate/8887 "2022-07-06T10:26:08Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@zzusunquan](https://discourse.vtk.org/u/zzusunquan)
#### Post date: [July 6, 2022, 10:26am UTC](https://discourse.vtk.org/t/vtk-delaunay2d-is-too-expensive-how-can-i-accelerate/8887/1 "2022-07-06T10:26:08Z")
I use the following code
```auto
// _pd is a vtkPolyData object only with points
// the code is c#
var delaunay = vtkDelaunay2D.New();
delaunay.SetTolerance(0.001);
delaunay.SetInput(_pd);
delaunay.Update();
```
the above code cost 100 millisecond level while the \_pd have 10,000 points,.
So i use c++ CGAL build delaunay2D ， in c++ code, CGAL build delaunay2D cost 10 ms level with the same points. Then I Pass cell information to c#.
I think I’m using it wrong, can you tell me how to speed up the delaunay2D of vtk? I just need cell and point information。
---
### Author:  [@mwestphal](https://discourse.vtk.org/u/mwestphal)
#### Post date: [July 6, 2022, 11:18am UTC](https://discourse.vtk.org/t/vtk-delaunay2d-is-too-expensive-how-can-i-accelerate/8887/2 "2022-07-06T11:18:59Z")
This is a known issue with VTK delaunay implementation.
FYI @Tiffany_Chhim @Charles_Gueunet
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### Author:  [@Charles\_Gueunet](https://discourse.vtk.org/u/Charles_Gueunet)
#### Post date: [July 6, 2022, 11:23am UTC](https://discourse.vtk.org/t/vtk-delaunay2d-is-too-expensive-how-can-i-accelerate/8887/3 "2022-07-06T11:23:40Z")
We aim to improve the `vtkDelaunay2D` filter, I will keep you informed if we manage to get the time to do so.
If you want to keep the VTK flexibility while having the CGAL performance, please have a look at the [Vespa project](https://gitlab.kitware.com/vtk-cgal/vespa). This is a collection of VTK filters relying internally on CGAL. It provides a [Delaunay2D](https://gitlab.kitware.com/vtk-cgal/vespa/-/tree/master/vespa/Delaunay) vtkAlgorithm.
---
### Author:  [@zzusunquan](https://discourse.vtk.org/u/zzusunquan)
#### Post date: [July 6, 2022, 2:08pm UTC](https://discourse.vtk.org/t/vtk-delaunay2d-is-too-expensive-how-can-i-accelerate/8887/4 "2022-07-06T14:08:31Z")
Thank you very much for your prompt reply！
Although CGAL’s delaunay is fast, there seems to be a problem.
As you see, this fig is CGAL Delaunay，When the data is not closed like this, the edges will have strange triangles
the same data vtk is
I haven’t looked at the source code of vtk, but I want to ask if this is related to the
delaunay.SetTolerance(0.001);
set by vtk，
I use [fast-vtk-delaunay2d](https://github.com/tatsuya-s/faster-vtk-delaunay2d), Its performance is the same as cgal, and the reconstruction of this kind of data is not good.
As for the simultaneous use of vtk and cgal you said, I have already realized it. The point I’m struggling with now is this strange triangle, is there a good way to get rid of it?
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### Author:  [@Charles\_Gueunet](https://discourse.vtk.org/u/Charles_Gueunet)
#### Post date: [July 7, 2022, 6:35am UTC](https://discourse.vtk.org/t/vtk-delaunay2d-is-too-expensive-how-can-i-accelerate/8887/5 "2022-07-07T06:35:08Z")
Could you show use or share the point cloud you use ? Delaunay2D should be applied on planar data, or data that can trivially be projected onto a plan. Is it the case for you ?
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### Author:  [@zzusunquan](https://discourse.vtk.org/u/zzusunquan)
#### Post date: [July 7, 2022, 7:45am UTC](https://discourse.vtk.org/t/vtk-delaunay2d-is-too-expensive-how-can-i-accelerate/8887/6 "2022-07-07T07:45:05Z")
Thank you very much for your reply. I think I probably know where the problem is. It should be the problem of vtk and cgal for the accuracy of point coordinates. I converted my xy coordinates into int values to solve this strange triangle problem. in fact, the source data is originally int, because I used the depth map to generate point cloud, which went through a series of preprocessing into float.