Liquid level measurement by using an image method

Based on image processing technology, a non-contact liquid level measuring system is designed. Its consists of three parts: a COMS camera, three laser light sources, and a PC. The work principle of the device is that the laser beams from the laser source is irradiated to the liquid at a certain angle, and the image of the tank´s interior is picked up by the CMOS camera; then the light spots on the liquid surface is extracted by the technology of image processing; through the triangle area of the three light spots, the information about liquid-level can be obtained. The model of the measurement system is proposed in the paper, and the method of the calibration is given by using the least square algorithm. Experiment tests that the liquid level measuring method is reliable and stable.