Dynamic stability-aware physics-based optimization for monocular 3D gait reconstruction
TL;DR
A backend physical refinement method with dynamic stability constraints for monocular 3D gait reconstruction that significantly mitigates penetration, hovering, and foot skating, while improving event-based lateral stability and XCoM trajectory consistency, thereby better preserving natural gait geometry while enhancing physical plausibility.
Abstract
Existing monocular video human motion recovery methods can already estimate global trajectories and local poses in world coordinates. However, their results are still largely driven by visual fitting and often suffer from foot penetration, hovering, and foot skating, as well as trunk lean and center-of-mass sway that are inconsistent with the underlying dynamic balance mechanism of continuous walking. Existing methods based on physics engines or explicit dynamics are usually complex to solve and difficult to integrate tightly with current reconstruction pipelines. Methods based on differentiable physical priors are easier to integrate, but most focus on contact consistency or static stability modeling, and therefore cannot fully characterize the dynamic stability of continuous gait, which is jointly determined by velocity and support transition. To address this issue, we propose a backend physical refinement method with dynamic stability constraints for monocular 3D gait reconstruction. Given an initial human motion estimate in world coordinates, the method constructs velocity-dependent dynamic stability constraints based on the extrapolated center of mass (XCoM) theory, and jointly refines the full sequence by incorporating the effective center of pressure, foot-ground contact constraints, kinematic anchoring, and temporal smoothness. Experiments show that the proposed method significantly mitigates penetration, hovering, and foot skating, while improving event-based lateral stability and XCoM trajectory consistency, thereby better preserving natural gait geometry while enhancing physical plausibility.