where α, β, and γ are some constants, H is the mean curvature vector on Σ (area space), K is the Gaussian curvature on ∂Σ (boundary space), and dA is the induced area metrics on Σ. This model is curvature driven, invariant under the group of Möbius transformations (in particular, under rigid motions and scaling of the surface) and shown to be very useful in energy minimization problems [25] . Invariance of the energy under rigid motions leads to conservation of linear and angular momenta, and invariance under scaling plays a role in setting the size of complex parts of the intrinsic shapes (i.e., corners, wrinkles, folds, etc.). In other words, the position, gray-level characteristics, size, and orientation of the pattern of interest have minimal effect on the extracted features as long as the suitable patch is reserved for the analysis. In order to have simpler and more intuitive representation of the given model, we simply set α = 0 and β = γ = 1, and the equation turns into Willmore energy functional