T-Snake(2) Reference: Tim McInerney, Demetri Terzopoulos, T-snakes: Topology adaptive snakes, Medical Image Analysis, No ,pp73-91

Review T-snakes model A closed 2D contour consisting of a set of nodes connected in series. A discrete approximation to a conventional parametric snakes model.

T-snake Algorithm 1. For M time steps: (a) compute the external forces and internal forces acting on T-snake nodes and elements (b) update the node position 2. Perform reparameterization phase I 3. Perform reparameterization phase II

T-snake Algorithm 4. For all T-snake elements, check valid or not Valid if corresponding grid cell is still a boundary cell; Invalid T-snake elements and unused nodes are discarded 5. Use the grid vertices turned on in Phase II above ( if any) to determine new boundary cells and hence new T-snake nodes and elements

Apply T-snakes to medical image Geometric flexibility 1. To segment and reconstruct objects with significant protrusions, tubular objects, or objects with bifurcations. 2. Less sensitive to the initial placement

Apply T-snakes to medical image Topological adaptability Seamlessly split or merge and adapt to the topology of the target object

Apply T-snakes to medical image Multiple T-Snakes 1. Evolve concurrently on different CPUs t improve performance. 2. Seed T-snakes on several objects 3. Potentially automatic segmentation

Apply T-snakes to medical image Topology preservation 1. T-Snake can maintain the topology, guarantee that no self-intersections will occur 2. Topology-preserving deformation

Apply T-snakes to medical image Interactive control Intuitive interactive capability associated with standard snake is maintained. User can exert attraction or repulsion forces using mouse.

T-Surfaces Topology adaptive surfaces (T-surfaces) A discrete deformable closed-surface model A closed oriented triangular surface mesh