Supporting cuts and finite element deformation in interactive surgery simulation

Abstract

Interactive surgery simulations have conflicting requirements of speed and accuracy. In this paper we show how to combine a relatively accurate deformation model - the Finite Element (FE) method - and interactive cutting without requiring expensive matrix updates or precomputation. Our approach uses an iterative algorithm for an interactive linear FE de- formation simulation. The iterative process requires no global precompu- tation, so run-time changes of the mesh - that is, cuts - can be simulated efficiently. Cuts are performed along faces of the mesh; this prevents growth of the mesh without violating mass preservation laws. We present a robust method for changing the mesh topology, and a satisfactory heuris- tic for determining along which faces to perform cuts. Nodes within the mesh are relocated to align the mesh with a virtual scalpel. This prevents a jagged surface appearance. On the other hand it generates degeneracies, which are removed afterward.