  Rip currents pose a significant danger to those who visit beaches, as they
can swiftly pull swimmers away from shore. Detecting these currents currently
relies on costly equipment and is challenging to implement on a larger scale.
The advent of unmanned aerial vehicles (UAVs) and camera technology, however,
has made monitoring near-shore regions more accessible and scalable. This paper
proposes a new framework for detecting rip currents using video-based methods
that leverage optical flow estimation, offshore direction calculation, earth
camera projection with almost local-isometric embedding on the sphere, and
temporal data fusion techniques. Through the analysis of videos from multiple
beaches, including Palm Beach, Haulover, Ocean Reef Park, and South Beach, as
well as YouTube footage, we demonstrate the efficacy of our approach, which
aligns with human experts' annotations.
