International audienceWe propose an algorithm to estimate the motion between two images. This algorithm is based on the nonlinear brightness constancy assumption. The number of unknowns is reduced by considering displacement fields that are piecewise linear with respect to each space variable, and the Jacobian matrix of the cost function to be minimized is assembled rapidly using a finite element method. Different regularization terms are considered, and a multiscale approach provides fast and efficient convergence properties. Several numerical results of this algorithm on simulated and real geophysical flows are presented and discussed
