(Georgia Institute of Technology, 2013)
Hamid, Raffay; Kumar, Ramkrishan; Hodgins, Jessica K.; Essa, Irfan
We present a novel approach for robust localization of multiple people observed using a set of static cameras. We use this
location information to generate a visualization of the virtual offside line in soccer games. To compute the position of the offside line,
we need to localize players' positions, and identify their team roles. We solve the problem of fusing corresponding players' positional
information by finding minimum weight K-length cycles in a complete K-partite graph. Each partite of the graph corresponds to one of
the K cameras, whereas each node of a partite encodes the position and appearance of a player observed from a particular camera.
To find the minimum weight cycles in this graph, we use a dynamic programming based approach that varies over a continuum from
maximally to minimally greedy in terms of the number of graph-paths explored at each iteration. We present proofs for the efficiency
and performance bounds of our algorithms. Finally, we demonstrate the robustness of our framework by testing it on 82,000 frames of
soccer footage captured over eight different illumination conditions, play types, and team attire. Our framework runs in near-real time,
and processes video from 3 full HD cameras in about 0.4 seconds for each set of corresponding 3 frames.