Figure 1.

(a) A medial representation model $\mathbf{m}={({\mathbf{O}}^T,r,{\mathbf{s}}_0^T,{\mathbf{s}}_1^T)}^T$ at an atom, where O is the center of the inscribed sphere, r is the common spoke length, and (s₀, s₁) are the two unit spoke directions; (b) a skeleton of a hippocampus with 24 medial atoms; (c) the smoothed surface of the hippocampus.