# Curvature and Torsion from VMTK

**URL:** <https://discourse.slicer.org/t/curvature-and-torsion-from-vmtk/19417>\
**Category:** Support\
**Tags:** vmtk\
**Created:** [August 30, 2021, 9:07pm UTC](https://discourse.slicer.org/t/curvature-and-torsion-from-vmtk/19417 "2021-08-30T21:07:14Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Ge\_Tang](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ge_tang/32/9935_2.png) [@Ge\_Tang](https://discourse.slicer.org/u/Ge_Tang)\
**Post date:** [August 30, 2021, 9:07pm UTC](https://discourse.slicer.org/t/curvature-and-torsion-from-vmtk/19417/1 "2021-08-30T21:07:14Z")

</div>

Hi,  
I have problems reading the code from the VMTK source code.  
I am not sure if the curvature, torsion from the centerline property are calculated by averaging ([SlicerExtension-VMTK/ExtractCenterline.py at e01c4fea8e67d45c646f7c66a1183063dd06bcbb · vmtk/SlicerExtension-VMTK · GitHub](https://github.com/vmtk/SlicerExtension-VMTK/blob/e01c4fea8e67d45c646f7c66a1183063dd06bcbb/ExtractCenterline/ExtractCenterline.py#L888))? If so, since torsion has negative values, did they use the absolute value for averaging?  
I also checked the code for the network property. It seems the curvature and torsion are the averages of all the points ([SlicerExtension-VMTK/ExtractCenterline.py at e01c4fea8e67d45c646f7c66a1183063dd06bcbb · vmtk/SlicerExtension-VMTK · GitHub](https://github.com/vmtk/SlicerExtension-VMTK/blob/e01c4fea8e67d45c646f7c66a1183063dd06bcbb/ExtractCenterline/ExtractCenterline.py#L1028)). How does the VMTK deal with torsion? Thank you for your help!  
best,  
Ge