伪随机编码结构光系统的标定  

Calibration of structured light system using pseudo-random coding

作　　者：唐苏明[1] 张旭[1] 屠大维[1] 

机构地区：[1]上海大学机电工程与自动化学院上海市智能制造及机器人重点实验室,上海200072

出　　处：《仪器仪表学报》2014年第6期1354-1362,共9页Chinese Journal of Scientific Instrument

基　　金：国家自然科学基金(51205244);数字制造装备与技术国家重点实验室(华中科技大学)开放基金(DMETKF2013007)资助项目

摘　　要：提出了一种采用伪随机编码原理生成彩色编码图案的结构光系统标定方法。首先,结构光系统向带有棋盘格图案的标定板投射白光,拍摄棋盘格图像,随后将棋盘格图案用白纸完全遮盖,投射彩色编码图案,并拍摄彩色编码图像。其次,采用一种基于K-均值聚类的角点自动提取方法提取伪随机编码图像的角点信息,利用彩色角点信息和射影变换原理建立摄像机图像和投影仪图像的对应关系,根据此对应关系,将三维空间特征点在摄像机坐标系下的图像坐标转换成投影仪坐标系下的图像坐标,从而实现对摄像机和投影仪的同时标定。最后,充分利用伪随机编码图案的桥梁作用对结构光系统外参数进行了整体优化,进而完成系统标定。实验结果表明该方法的标定精度可达0.3像素,且利用此法获得的标定数据对物体进行重建曲面的质量良好。In this paper, a calibration method for structured light system is proposed, which adopts pseudo-random coding theory to generate the color coded pattern. The structured light system first projects white light onto a calibration board with chessboard pattern and captures a corresponding image, then the color coded pattern is emitted onto the same calibration board that has been covered with a white paper and a color coded image is captured. Second, an automatic corner detection method based on K-means clustering is adopted to extract the color corner information of the pseudo-random coded image; the corresponding relation between the camera image and the projector image is determined using the color corner information and the projective transformation theory; according to this corresponding relation, the image coordinates of the 3D chessboard corner in the projector coordinate system is determined from the image coordinates in the camera coordinate system, so the projector and camera are calibrated simultaneously. Finally, the extrinsic parameters of the structured light system are integrally optimized with the help of pseudo-random coded pattern, and the calibration of the structured light system is accomplished. The experiment results show that the precision of the reverse projection error is only 0.3 pixels ; using the calibrated parameters, the structured light system was used to measure some test objects, and the quality of the reconstructed surfaces is good.

关 键 词：结构光系统 标定 伪随机编码 K-均值聚类 射影变换 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]