Inverse solution for parameter estimation of a dynamic volume spline based forehead skin model

摘要

Human facial soft tissue is modelled by a dynamic volume spline and the parameters of this model are estimated from the actual human facial skin properties by the optimization-based inverse solution. In the literature, various compressive force-displacement experiments are conducted and the parameters of the proposed models are estimated from the actual force and the corresponding displacement values measured during the experiments. Different from the common techniques in the literature, the displacement is measured in this study not only for the point of force contact with the surface but also for the region around the contact point. This is done by 3D reconstructing the shape of the compressed surface from the multiple camera views. This data is very suitable for estimating the parameters of the dynamic volume spline model by using an optimization-based inverse solution. The inverse solution is tested for various simulations starting from various initial conditions. Also, the inverse solution is applied to the real data collected during the experiments. When the model is used with the estimated parameter values, it behaves in a very similar way to the actual tissue characteristic which is obtained during the force-displacement experiment. Finally, the estimated parameters are used to model and animate the human face for various forehead expressions.