Real-time height measurement with a line-structured-light based imaging system

This paper presents a line-structured-light based method for real-time height measurement. The measurement system consists of an industrial camera, a line-structured laser and a computer. The whole line light will be deflected and broken into short lines when there are height differences for the lighted surface. A combined method of Maximally Stable Extremal Regions (Mser) area segmentation and the Steger algorithm (named as M-Steger) was proposed to extract the center point of the light strips. The deflected distance of the two fitted lines was used to calculate the true height difference of the positions where the two light strips were projected. It is experimentally found that the M-Steger method is advantageous in terms of extraction accuracy, computing time, and anti-noise. The maximum measurement errors for a flat and non-flat surface were about 4% and 5% respectively. This method was applied for real-time monitoring the height of the sprayed concrete during tunnel wet spraying.