Analysing the hovering flight of the hummingbird using statistics of the optical flow field

We propose a new method to analyse and characterise the hummingbird wing dynamics using statistical measures from an optical flow field. The method starts by computing a dense optical flow, using a multiscale spatial representation. First the pixels with larger velocities are retained as the support of the flow field, formed by the wings motion. Then, the global angular velocity is calculated as a function of the time during the hummingbird stroke. Additionally, each wing is segmented and the spatial variance of the velocity orientation is computed, providing the instants of principal stroke deformation. Finally a local measure of orientation deviation allows to localise the region of maximal torsion. Preliminary results show a compact and coherent description of the hovering flight dynamics of the hummingbird.