A dual-projector three-dimensional measurement model for shading problem of micro-scale object complex surface

Considering the inherent defects of the traditional triangulation method, always a shadow area is produced in the image collected by the camera. In this work, based on the traditional monocular vision measurement system, an auxiliary light source was added to alleviate the shadow problem. Two symmetrical digital light processing (DLP) projectors were also employed to project the modulated monochrome red fringe patterns and the monochrome blue fringe patterns onto the object, whereas the distorted fringe patterns were captured by the colour camera. The image collected by the colour camera was separated, whereas the deformation fringe information of the measured object was obtained in the red channel and blue channel, respectively. Fusion of red and blue channels information to eliminate measurement shadows. From the experimental results, the root mean square error (RMSE) of the system was about 6µm, and this method can effectively solve the shadow problem in small object measurement.