Water Level Detection from Video with Fir Filtering

This paper proposes how to detect water level from a video signal for use of automatic river surveillance. The water level is recognized as a boundary line between the land region and the water region. A conventional method uses a "vertical" edge detector to extract a horizontal line as the running water surface. "Subtraction" of frames is also accompanied to make it robust to horizontal line like disturbances. A new approach in this report applies "addition" of frames and a "horizontal" edge detector to distinguish water region and land region. Variance of each line of a filtered video frame is used as a feature value. Optimization of the edge detection filter is also discussed so that the system becomes robust to changes of lighting condition.