# The spline function for spline curve in Markups

**URL:** <https://discourse.slicer.org/t/the-spline-function-for-spline-curve-in-markups/29381>\
**Category:** Support\
**Tags:** markups\
**Created:** [May 9, 2023, 3:54pm UTC](https://discourse.slicer.org/t/the-spline-function-for-spline-curve-in-markups/29381 "2023-05-09T15:54:56Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Chuan](https://avatars.discourse-cdn.com/v4/letter/c/4da419/32.png) [@Chuan](https://discourse.slicer.org/u/Chuan)\
**Post date:** [May 9, 2023, 3:54pm UTC](https://discourse.slicer.org/t/the-spline-function-for-spline-curve-in-markups/29381/1 "2023-05-09T15:54:57Z")

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Hi,  
Does anyone how in 3D slicer, which kind of spline curve function is used in markups?

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/0/e/0ec09652033ecae0331a28713aa8d4aea311e847.png)  
I can only see the curve type is spline, but have not found out which kind of function is used for this Spline type.

Best regards,  
Chuan

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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, 2:02am UTC](https://discourse.slicer.org/t/the-spline-function-for-spline-curve-in-markups/29381/2 "2023-05-10T02:02:55Z")

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Cardinal or Kochanek spline is used. You can find details in the source code [here](https://github.com/Slicer/vtkAddon/blob/main/vtkCurveGenerator.cxx).