【作者】 陈亮辉；

【导师】 胡家升；

【作者基本信息】 大连理工大学 ， 测试计量技术及仪器， 2006， 硕士

【摘要】 三维轮廓测量在逆向工程、机器视觉、在线产品检测以及医疗诊断等领域的应用日益广泛,本文探讨了一种非接触快速获取物体三维轮廓的方法,即基于结构光投影的三维轮廓测量方法。其原理为向被测物体表面投影结构光图样,从与投影光轴成一定角度的方向获取由于物体高度变化而在其表面产生的变形图像,通过由物体表面的变形图像提取相位信息来实现物体三维轮廓测量。 本文主要工作包括以下几方面: (1) 以典型的交叉光轴系统为基础,介绍了采用结构光方法进行三维轮廓测量的基本原理,讨论了利用傅立叶变换方法提取相位时遇到的问题,针对傅立叶变换方法受被测物体梯度的限制,提出了p相移技术提高测量范围的方案。 (2) 介绍了相位展开的基本原理、主要的相位展开方法,就相位展开过程中噪声会导致相位误差传递的问题,提出了基于可靠性排序的相位展开算法。算法的核心就是基于可靠性的判别标准和队列排序,先对具有高可靠性值的像素点进行相位展开,这样很好地避开了噪声的影响,克服了传统相位展开算法中的误差传递问题,相位展开实验结果表明这种算法是可行的、有效的。 (3) 介绍了论文采用的系统标定方法,并从理论上分析了系统误差,基于分析结果搭建了三维轮廓测量的实验系统,实验系统利用计算机控制投影仪来投影结构光,由CCD摄像机获取变形的结构光图像,完成了系统的硬件和软件设计工作,实验系统结构简单、易于实现。 论文对测量中的关键技术,如相位展开、系统标定等进行了深入的研究,利用基于可靠性排序的相位展开算法能够避免噪声引起的误差传递,而隐参数标定方法实现简单,实验结果说明采用结构光方法进行三维轮廓测量能够获得比较满意的结果。更多还原

【Abstract】 Three-dimensional profile measurement is now widely applied in different areas, such as reverse engineering, computer vision, on-line product inspection and medical diagnosis. A non-contact, simple and rapid method for three-dimensional profile measurement is presented in this paper, which is based on structured light projection. The principle of this method is to project a computer-generated structured light pattern on the surface of the measured object, and then a distorted pattern caused by the object height is recorded from another angle. Finally surface profile of the object is obtained by demodulating the phase information from the deformed image.What is contained in the thesis is as following:(1) The mathematical model of three-dimensional profile measurement using structured light method is introduced based on a typical crossed-optical-axes geometry, and then discuss the problems faced in phase demodulation using Fourier transform method. A p phase shifting method is proposed to increase measurement range which is confined by object gradient.(2) The principle of phase unwrapping and main phase unwrapping methods is introduced, and a new phase unwrapping algorithm which is based on reliability ordering is proposed to overcome the phase error propagation problem caused by noise. The core of the method is that pixel with higher reliability value will be phase unwrapped earlier according to reliability criteria and queue ordering. In this way it can bypass noise automatically, and solve problem of error propagation, and the experimental results of phase unwrapping show that this algorithm is effective for noise.(3) A system calibration method is presented firstly, and then the system error is analyzed theoretically. Based on the theoretical analysis and computer simulation, we design an experimental system for three-dimensional profile measurement. The system is fulfilled with a computer controlled projector to display structured light and a CCD camera to detect the deformed image, and the hardware and software of the system are designed also.The key techniques like phase unwrapping and system calibration are investigated in this paper, and experiments show that it can obtain good results using structured light method to measure three-dimensional profile.更多还原