Application of optical flow for river velocimetry

[Departement_IRSTEA]Eaux [TR1_IRSTEA]ARCEAUInternational audienceWe present a new method for the application of image-based river velocimetry. Our method is dedicated to high velocity river flows and it is based on an optical flow scheme. Unlike traditional Particle Image Velocimetry (PIV) methods, optical flow provides dense estimations and it is highly adaptable to different applications. We therefore propose a new physics-based optical flow derived from scalar transport equation and augmented with a weighted diffusion term. The results are evaluated on a Lagrangian basis by means of trajectories reconstruction. The trajectories of few passive particles of interest are reconstructed, based on the successive estimated vector fields. Our method outperformed traditional PIV-based and original optical flow methods