vtkvmtkPolyDataCenterlineSection just gives a value for each centerline section (region between two bifurcations), so it is not very useful for analyzing a single vessel branch.
RequestData is never public, that is called by the VTK filter pipeline executor.
Most recent Slicer versions can now store and visualize scalar arrays associated with centerlines. I’ve now updated “Extract Centerline” module in SlicerVMTK to add radius array to the curve node (it will be available for Slicer Preview Release form tomorrow). This can be used to color the centerline, but it could be also used in Cross-Section analysis module to show “Diameter” in “More” section.
