# How the definition of tortuosity in VMTK?

**URL:** <https://discourse.slicer.org/t/how-the-definition-of-tortuosity-in-vmtk/12503>\
**Category:** Support\
**Created:** [July 13, 2020, 12:01pm UTC](https://discourse.slicer.org/t/how-the-definition-of-tortuosity-in-vmtk/12503 "2020-07-13T12:01:35Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![wwx992881](https://avatars.discourse-cdn.com/v4/letter/w/ebca7d/32.png) [@wwx992881](https://discourse.slicer.org/u/wwx992881)\
**Post date:** [July 13, 2020, 12:01pm UTC](https://discourse.slicer.org/t/how-the-definition-of-tortuosity-in-vmtk/12503/1 "2020-07-13T12:01:35Z")

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HI,All  
I’ve extracted the center line,and I don’t know the definition of tortuosity in 3D table.

 ![微信图片_20200713195110](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/e/8/e89040b9c7959efb59c1c0540f6ce4cf463c530b.png)  
I see a definition of tortuosity in the literature:Tortuosity was defined as L/D–1, where L is the length of the centre line from one point to another point, and D is the straight-line distance between these two points.I want to know the definition of tortuosity in the 3d slicer is the same as this one.  
Thanks~!

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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:** [July 13, 2020, 1:49pm UTC](https://discourse.slicer.org/t/how-the-definition-of-tortuosity-in-vmtk/12503/2 "2020-07-13T13:49:47Z")

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Yes, tortuosity is computed as the ratio between the centerline length and the distance between the line endpoints - 1. Since VMTK is open-source, you can always verify what the exact computation is. Implementation of this metric is available [here](https://github.com/vmtk/vmtk/blob/94d2789a8cd22197352e25e1d65e4644d751e870/vtkVmtk/ComputationalGeometry/vtkvmtkCenterlineGeometry.cxx#L284).

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**Author:** ![wwx992881](https://avatars.discourse-cdn.com/v4/letter/w/ebca7d/32.png) [@wwx992881](https://discourse.slicer.org/u/wwx992881)\
**Post date:** [July 13, 2020, 1:54pm UTC](https://discourse.slicer.org/t/how-the-definition-of-tortuosity-in-vmtk/12503/3 "2020-07-13T13:54:25Z")

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Thanks!That will help me a lot.