“…By solving the so-called intrinsic heat equation one can directly find a position vector of a curve (see, e.g., [17,18,19,33,39,40]). There are also other direct methods based on solution of a porous medium-like equation for curvature of a curve [31,32], a crystalline curvature approximation [22,23,44], special finite difference schemes [28,29], and a method based on erosion of polygons in the affine invariant scale case [34]. By contrast to the direct approach, level set methods are based on introducing an auxiliary function whose zero level sets represent an evolving family of planar curves undergoing the geometric equation (1.1) (see, e.g., [36,41,42,43,26]).…”