Dynamic cylindrical free-form deformation for interactive simulation of tool-tissue interaction

Abstract

Background Dynamic lattice-based free-form deformation (FFD) allows efficient simulation of global deformation of complex geometric objects. However, directly imposing a number of position constraints due to contact with a tool is non-trivial since it is an over-determined problem. Method This paper extends the FFD to directly impose a number of position constraints for the objects to be embedded in (rounded) cylindrical lattice structures. The position constraints are applied by enabling each surface point to locally deform along the near-normal direction to the surface. Result The computational time of the local deformation is independent of the number of constrained points other than finite element method. As a real-time application, the proposed method is applied to colonoscopic polypectomy simulation running at over 60Hz. Conclusion The proposed method allows efficient simulation of the global and local deformations of complex geometric objects while achieving accurate tooltissue interaction in a realistic and robust manner. Copyright (c) 2012 John Wiley & Sons, Ltd.