Fast soft-body models for musculoskeletal modelling: technical report no. DCSE/TR-2012-5

Soft-body models represent elastic deformable objects in a virtual environment, which makes them particularly appropriate for a simulation of objects made of organic materials. Simulation environments created for medical purposes are the most usual applications that employ soft bodies. We present a model of muscles for one of such environments. The model is based on the mass-spring systems, which use point-mass particles connected by fictional springs to represent the deformable object. In this particular case, the particles are obtained by sampling the muscle fibres that stretch through the interior of the muscle and then connected by springs using a given pattern. Several spring layout patterns, as well as various different parameters of the mass-spring system, were tested in order to find out the ones most suitable for the muscle models. Further on, a mechanism for collision detection and response suitable for the purpose was designed, implemented and tested. The mechanism is able to handle collisions between a rigid and a soft body (a bone and a muscle) as well as between two soft bodies (two muscles). The model ai ms for interactivity rather than perfect physical accuracy of the model. The solution is a part of the EC funded project VPHOP - The Osteoporotic Virtual Physiological Human (FP7-ICT-223865) that is dedicated to improvement of the effectiveness of osteoporosis prediction and treatment