Fig. 5
From: A robust approach to 3D neuron shape representation for quantification and classification
Spoke is a vector connecting a skeleton point and that skeleton point’s one of two closest surface points. The vector points from the skeleton point to the surface point. Green dashed lines represent the implicit surface of an object, blue dot is one skeleton point, orange dots represent surface points, and the arrow represents a spoke. Spoke is perpendicular to the object surface at the surface point