# How can I draw normal vectors of a centerline in the 3D slicer?

**URL:** <https://discourse.slicer.org/t/how-can-i-draw-normal-vectors-of-a-centerline-in-the-3d-slicer/37933>\
**Category:** Support\
**Tags:** centerlines, vmtk-centerline\
**Created:** [August 18, 2024, 5:11pm UTC](https://discourse.slicer.org/t/how-can-i-draw-normal-vectors-of-a-centerline-in-the-3d-slicer/37933 "2024-08-18T17:11:32Z")\
**Posts on this page:** 1\
**Showing post:** 4

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [August 19, 2024, 8:17am UTC](https://discourse.slicer.org/t/how-can-i-draw-normal-vectors-of-a-centerline-in-the-3d-slicer/37933/4 "2024-08-19T08:17:01Z")

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You can easily draw the tangent, normal, and binormal vector directions for a curve. We normally use this for testing. How to get this feature:

1. Open the Python console in Slicer (`Ctrl`+`3`)
2. Copy-paste the [vector drawing code](https://github.com/Slicer/Slicer/blob/bf4af8a947a6bf080ce09a199c379cdb4394e7ae/Modules/Loadable/Markups/Testing/Python/MarkupsCurveCoordinateFrameTest.py#L14-L76) from into the Python console
3. Draw normals for the first curve in the scene by copy-pasting this code into the Python console:

```python
curveNode = slicer.mrmlScene.GetFirstNodeByClass("vtkMRMLMarkupsCurveNode")
addCoordinateSystemUpdater(createCoordinateSystemsModel(curveNode))

```

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_[View the full topic](https://discourse.slicer.org/t/how-can-i-draw-normal-vectors-of-a-centerline-in-the-3d-slicer/37933)._