Measurement-based modeling and fabrication of deformable materials for human faces

Abstract

<p>This thesis investigates the combination of data-driven and physically basedtechniques for acquiring, modeling, and animating deformable materials,with a special focus on human faces. Furthermore, based on these techniques,we introduce a data-driven process for designing and fabricating materialswith desired deformation behavior.</p><p>Realistic simulation behavior, surface details, and appearance are still demandingtasks. Neither pure data-driven, pure procedural, nor pure physicalmethods are best suited for accurate synthesis of facial motion and details(both for appearance and geometry), due to the difficulties in model design,parameter estimation, and desired controllability for animators. Capturingof a small but representative amount of real data, and then synthesizing diverseon-demand examples with physically-based models and real data asinput benefits from both sides: Highly realistic model behavior due to realworlddata and controllability due to physically-based models.</p><p>To model the face and its behavior, hybrid physically-based and data-drivenapproaches are elaborated. We investigate surface-based representations aswell as a solid representation based on FEM. To achieve realistic behavior, wepropose to build light-weighted data capture devices to acquire real-worlddata to estimate model parameters and to employ concepts from data-drivenmodeling techniques and machine learning. The resulting models supportsimple acquisition systems, offer techniques to process and extract modelparameters from real-world data, provide a compact representation of thefacial geometry and its motion, and allow intuitive editing. We demonstrateapplications such as capture of facial geometry and motion and real-time animationand transfer of facial details, and show that our soft tissue modelcan react to external forces and produce realistic deformations beyond facialexpressions.</p><p>Based on this model, we furthermore introduce a data-driven process for designingand fabricating materials with desired deformation behavior. Theprocess starts with measuring deformation properties of base materials. Eachmaterial is represented as a non-linear stress-strain relationship in a finiteelementmodel. For material design and fabrication, we introduce an optimizationprocess that finds the best combination of base materials that meetsa user s criteria specified by example deformations. Our algorithm employsa number of strategies to prune poor solutions from the combinatorial searchspace. We finally demonstrate the complete process by designing and fabricatingobjects with complex heterogeneous materials using modern multimaterial3D printers.</p>