# 3D Slicer Curve Annotation

**URL:** <https://discourse.slicer.org/t/3d-slicer-curve-annotation/25305>\
**Category:** Support\
**Tags:** annotations\
**Created:** [September 16, 2022, 1:35pm UTC](https://discourse.slicer.org/t/3d-slicer-curve-annotation/25305 "2022-09-16T13:35:53Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![stevenagl12](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/stevenagl12/32/3391_2.png) [@stevenagl12](https://discourse.slicer.org/u/stevenagl12)\
**Post date:** [September 16, 2022, 1:35pm UTC](https://discourse.slicer.org/t/3d-slicer-curve-annotation/25305/1 "2022-09-16T13:35:53Z")

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Can anyone tell me what the equation that is used for the curve annotation tool is to calculate the curvature for the mean and max curvature metrics?

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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:** [September 16, 2022, 2:05pm UTC](https://discourse.slicer.org/t/3d-slicer-curve-annotation/25305/2 "2022-09-16T14:05:24Z")

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You can find the computation in the vtkCurveMeasurementsCalculator filter source code:

> <https://github.com/Slicer/Slicer/blob/2551f9f58637de6baf714d48543a717da3ee7197/Modules/Loadable/Markups/MRML/vtkCurveMeasurementsCalculator.cxx#L226-L239>