Tearing of membranes for interactive real-time surgical training

Tearing for interactive real-time surgical training is a problem rarely discussed in scientific publications. In this paper, an approach is presented to model the tearing of membranes. Based on a mesh of mass nodes connected by springs and triangles tears propagate along the springs of the mesh. Springs and triangles at the crack are divided up between both sides, keeping the number of triangles constant. Node stress indicates when and where the membrane tears. Tear threshold of a node depends on the node's location in the mesh. Edge nodes tear more easily than internal nodes. Nodes at the end of a crack have the lowest threshold to favor the propagation of already created cracks. Compared to a straightforward solution of the problem, the deletion of over stretched springs, the approach has some advantages. The presented algorithm shows a more plausible result for small resolutions that are used by the real-time simulation of stiff materials. On high-resolution meshes, there is only little difference between both approaches. Two training modules for the ophthalmo-surgical simulator EYESI use the presented tearing method to model realistic membrane tearing.