STC: A Skin Tension Constraint Model for Position-Based Dynamics

Accurate and real-time deformable tissue simulation is a key component of virtual surgical training systems. This study introduces a Skin Tension Constraint (STC) into the Position-Based Dynamics (PBD) framework to more effectively model the directional tensile behavior of the skin. To complement the limitations of conventional distance and volume constraints, STC indirectly simulates tensile responses on the skin surface using area changes and normal directions of triangular mesh elements. Additionally, the skin boundary is automatically extracted using CT-based density information, and the STC structure is designed to be compatible with existing grouping schemes for efficient GPU-based parallel processing. A static incision scenario was used to observe the difference in simulation outcomes depending on the presence of STC, and the results suggest that the proposed method can more naturally represent skin deformation and separation. This study presents a potential extension for modeling skin responses within the PBD framework.