A Three-Dimensional Measurement Method Based on Multiple Reflected Images

When multi-view structured light is used for three-dimensional measurement of metallic objects, the structured light images obtained by each camera exhibit obvious differences because the reflected light intensity significantly changes with the angle; thus, the degree of matching of images is reduced. At some locations with strong reflections, stray light can even render the measurement of line structured light impossible. Moreover, when the same parameter is used to match or process the image, the accuracy of the measurement is poor if materials with large differences in reflectivity and reflection performance arc simultaneously encountered. To mitigate these problems, a three-dimensional structured light measurement method and an instrument calibration method based on the formation of multiple reflected images arc proposed. The three-dimensional structured light measurement method solves the spatial coordinates of structured light image points by establishing a relation between the image and spatial coordinates of the corresponding points of the multiple reflected images. Experimental results indicate that to a certain extent, this method overcomes the problems of large brightness contrast and high reflectance encountered in structured light measurement of high-reflection surfaces. Moreover, the measurement accuracy in our experimental platform reaches the engineering requirement of +/- 0.1 mm.