# Measure Diameter using centerline length and surface

**URL:** <https://discourse.slicer.org/t/measure-diameter-using-centerline-length-and-surface/31382>\
**Category:** VMTK\
**Tags:** python\
**Created:** [August 26, 2023, 5:29pm UTC](https://discourse.slicer.org/t/measure-diameter-using-centerline-length-and-surface/31382 "2023-08-26T17:29:05Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![cams2b](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/cams2b/32/66506_2.png) [@cams2b](https://discourse.slicer.org/u/cams2b)\
**Post date:** [August 26, 2023, 5:29pm UTC](https://discourse.slicer.org/t/measure-diameter-using-centerline-length-and-surface/31382/1 "2023-08-26T17:29:05Z")

</div>

I am trying to extract the radius at each point on the centerline from my tubular mesh. I am using the vmtk script vmtkDistanceToCenterlines and setting the variable EvaluateCenterlineRadius = True.

I was expecting this function to return a radius for each function on the centerline, however, the number of points returned is equal to the number of points in the surface mesh. I am confused with what this result signifies and I am wondering if there is a way to extract what I am interested in.

````auto
    distance_calculator = vmtkscripts.vmtkDistanceToCenterlines()
    distance_calculator.Surface = output_surface
    distance_calculator.Centerlines = centerline_points
    distance_calculator.UseCombinedDistance = False
    distance_calculator.UseRadiusInformation = False
    distance_calculator.EvaluateCenterlineRadius = True
    distance_calculator.ProjectPointArrays = False
    distance_calculator.UseCombinedDistance = False

    distance_calculator.RadiusArrayName = "Radius"    
    distance_calculator.Execute()
    distance = distance_calculator.Surface
    distance_to_centerline = distance.GetPointData().GetArray("Radius")```

Thank you all in advance for your help.
````

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<div class="post-metadata">

**Author:** ![chir.set](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/chir.set/32/66982_2.png) [@chir.set](https://discourse.slicer.org/u/chir.set)\
**Post date:** [August 26, 2023, 6:25pm UTC](https://discourse.slicer.org/t/measure-diameter-using-centerline-length-and-surface/31382/2 "2023-08-26T18:25:29Z")

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If your requirements do not confine you to vmtkscripts, you may consider using Slicer itself.

By installing SlicerVMTK extension using the extensions manager, you’ll find [Cross-section analysis](https://github.com/vmtk/SlicerExtension-VMTK/blob/master/Docs/CrossSectionAnalysis.md) module that does what you want, and much more.