# How to create a mesh data from vtkPoints?
**URL:** https://discourse.vtk.org/t/how-to-create-a-mesh-data-from-vtkpoints/6585
**Category:** Support
**Created:** [September 9, 2021, 3:16am UTC](https://discourse.vtk.org/t/how-to-create-a-mesh-data-from-vtkpoints/6585 "2021-09-09T03:16:58Z")
**Posts on this page:** 12
**Page:** 1
### Author:  [@Kim\_William](https://discourse.vtk.org/u/Kim_William)
#### Post date: [September 9, 2021, 3:16am UTC](https://discourse.vtk.org/t/how-to-create-a-mesh-data-from-vtkpoints/6585/1 "2021-09-09T03:16:58Z")
Hi all.
I have a question about the how to create a mesh data.
I’m using the VTK 9.0 with the 3D Scanner.
I can represent the point cloud data with vtkGaussainMapper.
Previous inquiry:
> [@The PLY file is not working.](https://discourse.vtk.org/t/the-ply-file-is-not-working/924):
>
> Hi all. I have a question about PLY file load. I have two PLY files. (A) PLY file: It made by 3D Scanner. (B) PLY file: The sample PLY file from the link. Link: [http://graphics.im.ntu.edu.tw/~robin/courses/cg04/model/index.html](http://graphics.im.ntu.edu.tw/~robin/courses/cg04/model/index.html) The B file work normally but A file is not working on the same code. My code snippet is as below: vtkSmartPointer pPLYReader = vtkSmartPointer::New(); pPLYReader-\>SetFileName(“myPLY.ply”); pPLYReader-\>Update(); vtkSmartPointer mapper = vtkSmartPointer::New(); …
Now, I would like to represent the Mesh data from the vtkPoints.
But I’m not sure which example code to reference…
Could you please advise for me how to create a mesh data from the vtkPoints?
Thank you 🙂
Best regards,
William Kim
---
### Author:  [@Charles\_Gueunet](https://discourse.vtk.org/u/Charles_Gueunet)
#### Post date: [September 9, 2021, 7:54am UTC](https://discourse.vtk.org/t/how-to-create-a-mesh-data-from-vtkpoints/6585/2 "2021-09-09T07:54:23Z")
The best way would be to create a vtkPolyData, and use the `vtkPolyData::SetPoints` to give the list of points and `vtkPolyData::SetVerts` to give the `vtkCellArray` describing the cells around the points (so VTK can render the points).
An example can be found in [vtkPolyPointSource](https://gitlab.kitware.com/vtk/vtk/-/blob/master/Filters/Sources/vtkPolyPointSource.cxx#L133).
---
### Author:  [@Kim\_William](https://discourse.vtk.org/u/Kim_William)
#### Post date: [September 9, 2021, 8:34am UTC](https://discourse.vtk.org/t/how-to-create-a-mesh-data-from-vtkpoints/6585/3 "2021-09-09T08:34:58Z")
Thank you for your reply.
I saw your example but I can’t understand how to work it…
Do you mean that the vtkCellArray can represent the mesh data?
---
### Author:  [@Charles\_Gueunet](https://discourse.vtk.org/u/Charles_Gueunet)
#### Post date: [September 9, 2021, 8:47am UTC](https://discourse.vtk.org/t/how-to-create-a-mesh-data-from-vtkpoints/6585/4 "2021-09-09T08:47:00Z")
In VTK, points are only 3D coordinates. They serve as a support for cells.
To have a valid point cloud, you need:
- a `vtkDataSet` that support explicit points, here we will use a `vtkPolyData`
- the `vtkPoints` containing the points, which you already have
- the `vtkCellArray` containing the cells so you have a valid VTK data set
We can construct one like that:
```cpp
// vtk data set to fill
vtkNew myPolyData;
// compute a vtkIdList that contains ids of each points
vtkIdType numPoints = myVtkPoints->GetNumberOfPoints();
vtkSmartPointer pointIds = vtkSmartPointer::New();
pointIds->SetNumberOfIds(numPoints);
for (vtkIdType i = 0; i < numPoints; ++i)
{
pointIds->SetId(i, i);
}
// create a vtkCellArray from this list
vtkSmartPointer polyPoint = vtkSmartPointer::New();
polyPoint->InsertNextCell(pointIds);
// give the points and cells to the final poly data
myPolyData->SetPoints(myVtkPoints);
myPolyData->SetVerts(polyPoint);
```
In this code, I assume you have `myVtkPoints` that is the `vtkPoints` containing the positions of points in your point cloud
---
### Author:  [@Kim\_William](https://discourse.vtk.org/u/Kim_William)
#### Post date: [September 13, 2021, 7:39am UTC](https://discourse.vtk.org/t/how-to-create-a-mesh-data-from-vtkpoints/6585/5 "2021-09-13T07:39:40Z")
Thank you for your guide!
I added the above code to my code, but the renderwindow still shows it as points.
below is my code:
```auto
vtkSmartPointer pointIds = vtkSmartPointer::New();
pointIds->SetNumberOfIds(numPoints);
for (vtkIdType i = 0; i < numPoints; ++i)
{
pointIds->SetId(i, i);
}
// create a vtkCellArray from this list
vtkSmartPointer polyPoint = vtkSmartPointer::New();
polyPoint->InsertNextCell(pointIds);
// give the points and cells to the final poly data
m_vtkPolydata->SetPoints(m_vtkPCDPoints);
m_vtkPolydata->SetVerts(polyPoint);
vtkNew m_vtkGlyphFilter;
m_vtkGlyphFilter->SetInputData(m_vtkPolydata);
m_vtkGlyphFilter->Update();
vtkNew m_vtkPolydataMapper;
m_vtkPolydataMapper->SetInputData(m_vtkPolydata);
vtkNew m_vtkActor;
m_vtkActor->SetMapper(m_vtkPolydataMapper);
vtkNew m_vtkRenderer;
m_vtkRenderer->AddActor(m_vtkActor);
m_vtkRenderer->SetBackground(.1, .2, .3);
vtkNew m_vtkRenderWindow;
m_vtkRenderWindow->AddRenderer(m_vtkRenderer);
m_vtkRenderWindow->Render();
```
I referred to the below link, but I couldn’t make mesh data.
[https://kitware.github.io/vtk-examples/site/Cxx/Filtering/TriangulateTerrainMap/](https://kitware.github.io/vtk-examples/site/Cxx/Filtering/TriangulateTerrainMap/)
I’m sorry to bother you but could you please advise for me again?
---
### Author:  [@Kim\_William](https://discourse.vtk.org/u/Kim_William)
#### Post date: [September 13, 2021, 7:40am UTC](https://discourse.vtk.org/t/how-to-create-a-mesh-data-from-vtkpoints/6585/6 "2021-09-13T07:40:43Z")
[test.ply](https://discourse.vtk.org/uploads/short-url/jE0peHTLciZ4TbAR14Fsn2wGFiV.ply) (3.5 MB)
I attached the sample ply file.
---
### Author:  [@Charles\_Gueunet](https://discourse.vtk.org/u/Charles_Gueunet)
#### Post date: [September 13, 2021, 8:20am UTC](https://discourse.vtk.org/t/how-to-create-a-mesh-data-from-vtkpoints/6585/7 "2021-09-13T08:20:59Z")
Oh I see, you want to create a surface from your points. Maybe you should have a look at [vtkDelaunay2d](https://vtk.org/doc/nightly/html/classvtkDelaunay2D.html). This filter can take the polydata we created as input and should provide a triangulated surface like the one you want as output.
---
### Author:  [@Kim\_William](https://discourse.vtk.org/u/Kim_William)
#### Post date: [September 13, 2021, 8:46am UTC](https://discourse.vtk.org/t/how-to-create-a-mesh-data-from-vtkpoints/6585/8 "2021-09-13T08:46:45Z")
Thanks for your reply!
I already have tested with the vtkDelaunay2d sample code.
I modified the code as below, the **stack overflow** exception occurred. 😢
My code:
```auto
int main(int, char*[])
{
vtkNew colors;
vtkNew reader;
reader->SetFileName("test.ply");
reader->Update();
// Create a set of heights on a grid.
// This is often called a "terrain map".
vtkNew points;
points->DeepCopy(reader->GetOutput()->GetPoints());
// Add the grid points to a polydata object
vtkNew polydata;
polydata->SetPoints(points);
//... same as the sample code
}
```
---
### Author:  [@Charles\_Gueunet](https://discourse.vtk.org/u/Charles_Gueunet)
#### Post date: [September 13, 2021, 8:50am UTC](https://discourse.vtk.org/t/how-to-create-a-mesh-data-from-vtkpoints/6585/9 "2021-09-13T08:50:02Z")
Can you show the full code with the cell array computation and the call to the vtkDelaunay2d filter ?
---
### Author:  [@Kim\_William](https://discourse.vtk.org/u/Kim_William)
#### Post date: [September 13, 2021, 11:20pm UTC](https://discourse.vtk.org/t/how-to-create-a-mesh-data-from-vtkpoints/6585/10 "2021-09-13T23:20:00Z")
[Exam\_VTK.zip](https://discourse.vtk.org/uploads/short-url/uaooty8JII6mWOsAVb3jihgACne.zip) (2.0 MB)
Please see my full code. It is a modified code based on the vtkDelaunay2d sample code.
Thanks again…! 🙂
=============== modified ===============
I found that the solution for the ‘stack overflow’ exception.
There is no error if I increase the stack size.
[Project \> Properties \> Linker \> System \> StackSize]
But the converting speed from the point to vtkDelaunay2d is so slow.
Is there any way to speed up the conversion?
---
### Author:  [@Charles\_Gueunet](https://discourse.vtk.org/u/Charles_Gueunet)
#### Post date: [September 14, 2021, 11:20am UTC](https://discourse.vtk.org/t/how-to-create-a-mesh-data-from-vtkpoints/6585/11 "2021-09-14T11:20:08Z")
Nice you succeeded to convert your file.
What is the approximate size of your point cloud ? In your scene, it looks like you represent points using glyphs. This can also be a bottleneck on a large scene. Can you try to use the Point Gaussian representation instead ? This one is computed in the screen space and does not create additional geometry for each point.
---
### Author:  [@Kim\_William](https://discourse.vtk.org/u/Kim_William)
#### Post date: [September 15, 2021, 2:57am UTC](https://discourse.vtk.org/t/how-to-create-a-mesh-data-from-vtkpoints/6585/12 "2021-09-15T02:57:36Z")
Thank you for your guide 🙂
Actually what I want is just to represent the mesh data from the point data.
I think I have to study VTK library deeply, because there are so many functions.
So, if I have a further question I will create a new topic.
Thanks again!