# Regarding active scalars

**URL:** https://discourse.slicer.org/t/regarding-active-scalars/29244
**Category:** VMTK
**Created:** [May 2, 2023, 1:23pm UTC](https://discourse.slicer.org/t/regarding-active-scalars/29244 "2023-05-02T13:23:24Z")
**Posts on this page:** 2
**Page:** 1

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### Author: ![Mudrika](https://avatars.discourse-cdn.com/v4/letter/m/c57346/32.png) [@Mudrika](https://discourse.slicer.org/u/Mudrika)
#### Post date: [May 2, 2023, 1:23pm UTC](https://discourse.slicer.org/t/regarding-active-scalars/29244/1 "2023-05-02T13:23:24Z")

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Hello!

Can anyone help me with how can I monitor what active scalars can be calculated for the centerline model in VMTK extension. I am getting only 3 options, but my interest lies in the calculation of curvature, torsion, and tortuosity, which are not there in the drop down list. Can anyone help me with how can I include the option of more geometrical indices in it?

Thank you!

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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: [May 10, 2023, 4:36am UTC](https://discourse.slicer.org/t/regarding-active-scalars/29244/2 "2023-05-10T04:36:40Z")

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See information in this discussion:

> [@Curvature, torsion, tortuosity computation algorithms in VMTK](https://discourse.slicer.org/t/curvature-torsion-tortuosity-computation-algorithms-in-vmtk/29186):
>
> Hello! I am trying to calculate the geometric indices such as curvature, torsion and tortuosity from the extracted centrelines in 3D slicer by using VMTK extension. Can anyone please tell me what are the mathematical definitions used over here for calculations? Thanks!