电子白板系统中参数标定方法的研究

Parameters calibration algorithm in electronic whiteboard system

为了避开复杂繁琐的摄像机标定过程,提出了一种基于CCD摄像机的电子白板系统参数标定新方法,实现了开机自动标定系统参数的功能。采用Harris角点检测算法成功提取了参考点的像素坐标,并直接运用射影变换交比不变性,推导出白板边框图像像素距离与实际物理距离的映射关系式,进而获得了摄像机的光心坐标。简要分析影响系统标定精度的因素,并设计出减小标定误差的方案,最后搭建实验平台标定系统参数。实验结果表明:该标定方法实现简单,应用方便,且对于单位长度为1cm的标定块而言,标定误差小于0.04cm。

In order to avoid complicated process of camera calibration and achieve the function to calibrate parameters automatically at start-up, a new method of electronic whiteboard system calibration was proposed based on CCD camera. Image pixel coordinates of reference points were extracted by using Harris corner detection algorithm. According to the basic property of projective geometry, the relationship between image pixel points and actual points was de- rived, and the optical center coordinates of CCD camera were obtained. The factors affecting calibration precision were analyzed, the project for decreasing calibration error was designed, and the experiment platform was constructed to calibrate parameters. Experimental results show that the calibration algorithm has simple realization and convenient application, and the calibration error of the calibration block with 1 cm length is less than 0.04 cm.