3) Mean Curvature: Mean curvature (H) is an extrinsic measure and it describes the curvature as H = (κ 1 + κ 2 )/2. Unlike K, H is defined in the distributional sense. Note that mean curvature measure is the trace of local Hessian matrix H e . Mean curvature can be thought as a negative gradient (as a Laplacian) of the area functional due to its nice variational interpretation over the surface. This does not only give insights into the size of the local shape but also into the total symmetrical deviation from the sphere. Mean curvature is translation and rotation invariant, but not scale invariant. 4) Elongation: Shape elongation is one of the basic shape descriptors and it indicates flatness measure of the local shape [28] . In this paper, we used the ratio of principal curvatures to measure elongation as κ 2 /κ 1 with κ 2 ≤ κ 1 . Elongation measure is invariant with respect to a similarity transformation, and therefore, it is a robust feature that helps to identify curvilinear shapes. Elongation varies from −1 to +1, from hyperbolic to elliptic points.