The spectacle frames scanner is an important part in the non-modeling lens-edger system, for its function to measure the profile of the spectacle frames and elicit its 3D data for lens-edging. We propose a new spectacle frames scanner based on multi-linear structured light which is a non-contact type. The experiment devices of the proposed system include a portable projector, a 12mm prime lens and an area array CCD camera. The technology of binary stripes and single-camera image collection are used in the new scanner. The original stripes are modulated by the spectacle frames, so we can collect the images and demodulate the 3D data of the spectacle frames based on trigonometry theory. The factors that influence the measurement accuracy of the scanner system are analyzed and the relationship between structure parameters and measurement error of the system has been determined. According to the result of the simulation, we determine the optimal structure parameters of the spectacle frames scanner system. Experiment result for resin frames with high reflectivity is given.
Automatic eyeglass lens edging system is now widely used to automatically cut and polish the uncut lens based on the spectacle frame shape data which is obtained from the spectacle frame measuring machine installed on the system. The conventional approach to acquire the frame shape data works in the contact scanning mode with a probe tracing around the groove contour of the spectacle frame which requires a sophisticated mechanical and numerical control system. In this paper, a novel non-contact optical measuring method based on structured light to measure the three dimensional (3D) data of the spectacle frame is proposed. First we focus on the processing approach solving the problem of deterioration of the structured light stripes caused by intense specular reflection on the frame surface. The techniques of bright-dark bi-level fringe projecting, multiple exposuring and high dynamic range imaging are introduced to obtain a high-quality image of structured light stripes. Then, the Gamma transform and median filtering are applied to enhance image contrast. In order to get rid of background noise from the image and extract the region of interest (ROI), an auxiliary lighting system of special design is utilized to help effectively distinguish between the object and the background. In addition, a morphological method with specific morphological structure-elements is adopted to remove noise between stripes and boundary of the spectacle frame. By further fringe center extraction and depth information acquisition through the method of look-up table, the 3D shape of the spectacle frame is recovered.
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