“…In 2-D, the use of the double angle method is well-known [1], [10], but in 3-D it remained an obstacle that prevented the computation of curvature in 3-D. Therefore, traditional 3-D methods are applied to segmented images, or even on curves represented by ordered points, which enables one to fit a parametric model to the curve [11]- [14]. These methods rely heavily on the preceding segmentation, labeling, and orderings steps, which may fail due to noise or the presence of a bundle of space curves comparable to a lock of hair.…”