Embedded implementation of image-based water-level measurement system

This paper proposes an embedded system for measuring the water level on a river using a camera. One of the main problems of using a camera in water-level measurement is that the light reflection on water surface changes rapidly. To solve this problem, this paper uses the property that variation of light reflection on the ruler showing the scale is relatively smaller than on the water surface. To emphasise this difference of light reflectance on the ruler surface and water surface, the proposed method accumulates the degree of light reflectance variation between the current image and the previous images and constructs a histogram using them. In this histogram, the boundary between the ruler and water surface is appeared as the sharpest drop point. To take into account the noise effects, the proposed algorithm finds the candidate points first and then finally select the water level among them using the reference water. The reference water level is roughly determined as the sharpest drop point in the histogram of the binary image. By installing the proposed system on actual river and testing the water-level measuring experiment in real time, its efficiency has been confirmed.