# How to show a polyline with arbitrary width and nice joins between the nodes?
**URL:** https://discourse.vtk.org/t/how-to-show-a-polyline-with-arbitrary-width-and-nice-joins-between-the-nodes/3316
**Category:** Support
**Created:** [May 15, 2020, 2:36pm UTC](https://discourse.vtk.org/t/how-to-show-a-polyline-with-arbitrary-width-and-nice-joins-between-the-nodes/3316 "2020-05-15T14:36:26Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@normanius](https://discourse.vtk.org/u/normanius)
#### Post date: [May 15, 2020, 2:36pm UTC](https://discourse.vtk.org/t/how-to-show-a-polyline-with-arbitrary-width-and-nice-joins-between-the-nodes/3316/1 "2020-05-15T14:36:26Z")
Hi
Have a look at the sample below. I’ve got a polyline and want to show that line with an arbitrary width.
In the sample, I essentially follow [this](https://lorensen.github.io/VTKExamples/site/Cxx/Visualization/LineWidth/) example to achieve this, for a polyline that I extracted with [vtkFeatureEdges](https://lorensen.github.io/VTKExamples/site/Cxx/Meshes/BoundaryEdges/). It appears that the line is drawn using quads per line-segment, however the result doesn’t look satisfactory.
Is it possible to create a polyline with nice joins? I found the [ribbon filter](https://lorensen.github.io/VTKExamples/site/Java/PolyData/RibbonFilter/), but it requires me to set a normal. Instead, I would rather like to see a tube that goes along that line.
I could possibly use [vmtkcenterlinemodeller](http://www.vmtk.org/vmtkscripts/vmtkcenterlinemodeller.html), but wondered if there is a pure VTK option. I need this just for visualization.
Thanks
* * *
**Update** : I found [vtkTubeFilter](https://vtk.org/doc/nightly/html/classvtkTubeFilter.html#details) that does the job much better. But still, it lacks the possibility to create nice joins.
```python
def polylineToTube(edges, radius, resolution=10):
tube = vtk.vtkTubeFilter()
tube.SetInputData(edges)
tube.SetRadius(radius)
tube.SetNumberOfSides(resolution)
tube.SidesShareVerticesOff()
tube.Update()
return tube
```
* * *
**Update 2** : If really desperate, one could use implicit functions to compute the tube. It’s super slow, but it works 🙂
```python
def polylineToTube(edges, radius, resolution=10, sampling=400):
modeller = vtk.vtkImplicitModeller()
modeller.SetSampleDimensions(sampling, sampling, sampling)
modeller.SetInputData(edges)
contours = vtk.vtkContourFilter()
contours.SetInputConnection(modeller.GetOutputPort())
contours.SetValue(0, radius) # generate iso-surface at radius
contours.Update()
return contours
```
---
### Author:  [@normanius](https://discourse.vtk.org/u/normanius)
#### Post date: [May 15, 2020, 5:19pm UTC](https://discourse.vtk.org/t/how-to-show-a-polyline-with-arbitrary-width-and-nice-joins-between-the-nodes/3316/2 "2020-05-15T17:19:47Z")
Okay. I finally figured out what was wrong. 🤦♂️
`vtkTubeFilter` is perfectly able to join the segments. But the issue was with `vtkFeatureEdges`, which was returning a multi-line (that is a `vtkPolyData` containing multiple line-segments, instead of one single polyline. Flattening this polyline fixed the problem for me.
This is how I did it:
```python
edges = vtk.vtkFeatureEdges()
edges.SetInputData(source)
edges.BoundaryEdgesOn()
edges.ManifoldEdgesOff()
edges.NonManifoldEdgesOff()
edges.FeatureEdgesOff()
edges.Update()
stripped = vtk.vtkStripper()
stripped.SetInputData(edges.GetOutput())
stripped.Update()
tube = vtk.vtkTubeFilter()
tube.SetInputData(stripped.GetOutput())
tube.SetRadius(radius)
tube.SetNumberOfSides(resolution)
tube.Update()
```
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### Author:  [@\_11](https://discourse.vtk.org/u/_11)
#### Post date: [February 17, 2022, 1:30pm UTC](https://discourse.vtk.org/t/how-to-show-a-polyline-with-arbitrary-width-and-nice-joins-between-the-nodes/3316/3 "2022-02-17T13:30:34Z")
> [@normanius](#):
>
> `polylineToTube`
Hi, what is the input of edge? Could you repost the link for the example because the original one is down.
Thanks!
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### Author:  [@normanius](https://discourse.vtk.org/u/normanius)
#### Post date: [March 3, 2022, 11:28am UTC](https://discourse.vtk.org/t/how-to-show-a-polyline-with-arbitrary-width-and-nice-joins-between-the-nodes/3316/4 "2022-03-03T11:28:52Z")
What do you mean by “What is the input of edge”?
The LineWidth example is now [here](https://kitware.github.io/vtk-examples/site/Cxx/Visualization/LineWidth/).
---
### Author:  [@\_11](https://discourse.vtk.org/u/_11)
#### Post date: [March 3, 2022, 12:00pm UTC](https://discourse.vtk.org/t/how-to-show-a-polyline-with-arbitrary-width-and-nice-joins-between-the-nodes/3316/5 "2022-03-03T12:00:14Z")
Hi, thanks a lot for your reply! I mean the input parameter for the function `polylineToTube ` . Is radius just a list of float number? But what is the `edges` ?
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### Author:  [@normanius](https://discourse.vtk.org/u/normanius)
#### Post date: [March 3, 2022, 12:07pm UTC](https://discourse.vtk.org/t/how-to-show-a-polyline-with-arbitrary-width-and-nice-joins-between-the-nodes/3316/6 "2022-03-03T12:07:38Z")
Hi Padix
`edges` is a vtkPolyData object representing a line. As I wrote in the OP, I extracted `edges` with `vtkFeatureEdges`. See here for an [example](https://kitware.github.io/vtk-examples/site/Python/Meshes/BoundaryEdges/).
Yes, radius is a float representing the radius of the line to “draw”.
HTH