  We introduce MultiPhys, a method designed for recovering multi-person motion
from monocular videos. Our focus lies in capturing coherent spatial placement
between pairs of individuals across varying degrees of engagement. MultiPhys,
being physically aware, exhibits robustness to jittering and occlusions, and
effectively eliminates penetration issues between the two individuals. We
devise a pipeline in which the motion estimated by a kinematic-based method is
fed into a physics simulator in an autoregressive manner. We introduce distinct
components that enable our model to harness the simulator's properties without
compromising the accuracy of the kinematic estimates. This results in final
motion estimates that are both kinematically coherent and physically compliant.
Extensive evaluations on three challenging datasets characterized by
substantial inter-person interaction show that our method significantly reduces
errors associated with penetration and foot skating, while performing
competitively with the state-of-the-art on motion accuracy and smoothness.
Results and code can be found on our project page
(http://www.iri.upc.edu/people/nugrinovic/multiphys/).
