基于双频彩色光栅投影测量不连续物体三维形貌

为减少多频条纹相移法进行三维形貌测量时的投影条纹数量，提高测量速度, 提出了采用双频四步相移彩色条纹投影技术来准确测量具有台阶状不连续或孤立物体表面三维形貌的方法。利用计算机将高低两种不同频率的正弦条纹分别输入彩色图像的红色和蓝色通道合成为彩色条纹，由数字视频投影仪将四步相移彩色条纹投影到被测物体，然后利用彩色CCD或CMOS相机采集4幅彩色条纹图并存储于计算机中。基于色彩分离技术得到8幅两种不同频率的四步相移条纹图并由图像灰度算法获得1幅反映背景的灰度图像；由低频条纹确定台阶状的物体边缘，高频条纹计算物体的形貌，并通过背景图像的二值化定位阴影和不连续区域。提出的方法仅用4幅彩色图像完成了台阶状不连续或孤立物体三维形貌的准确测量。与现有的多频4步相移条纹投影形貌测量技术需要8~12幅图像相比，该方法有效地减少了条纹投影与图像采集的数量。  

光学三维测量技术与应用

光学三维测量技术是一种可视化的测量技术,能完成复杂形体的点、面、形的三维测量,能实现非接触测量,在制造业和航空航天领域得到广泛应用。航空三维激光扫描与摄影测量技术利用激光测距原理和航空摄影测量原理,与基于全球定位系统(GPS)和惯性测量装置(IMU)的机载定位定向系统(POS)联接,可以快速获取大面积地球表面三维数据。本文对光学三维测量技术和航空三维激光扫描技术做一简单介绍,给出三维激光扫描技术在航空航天领域的几个应用。  

CAD-based environment to bridge the gap between product design and tolerance control

Mechanical product quality is strongly influenced by the respect of Geometrical Tolerances (GT). On the other hand, competitiveness forces companies to improve their productivity making the tolerance verification process faster and faster and more flexible. Component control by 3D full field optical digitizing systems and specific CAD-based (Computer Aided Design) inspection software tools are important steps forward for the achievement of the above-mentioned goals. However, the adoption of these solutions in industry is minimal. This may be due both to technological factors, i.e. poor systems usability, and organizing factors, i.e. clear separation between design department and quality control department. In this context, our research aims at developing a new easy to use CAD-based tool for simulating, driving and optimizing the GT inspection process. Once a component has been digitized, the developed software system automatically realizes the tolerances virtual control. Hence, the designer can prescribe tolerances, pilot the measurement system and verify the component conformity. The implemented tool is based on Full of Information (FoI) CAD models, which contain tolerance data, linked to a knowledge database, where measurement strategies and verification rules are stored. A computation engine calculates the measurement paths and performs the tolerances verification. The prototypal system has been tested on different real cases. Experimental results showed high performances in terms of timesaving and robustness.  

面向MEMS构件在线检测和三维外型测量的立体视觉系统

开发了可用于MEMS微制造和微装配过程的一种面向MEMS构件的在线监测和三维外型测量的视觉系统。介绍了该系统的设计、结构、工作原理及实现，并讨论了立体视觉模块的一些关键技术。参考微操作系统的原理，将立体视觉技术引入MEMS构件的检测，实现了由体视显微镜和一个CCD摄像机构建光学系统的三维外型视觉测量系统。实验结果表明，该系统是一种有效的三维检测解决方案。加以少量结构改进，该系统可以用于微制造和微操作过程中对MEMS构件的在线监测和三维外型的视觉测量。  

A low cost 3D shape measurement method based on a strip shifting pattern

We present a simple, low cost but fast 3D shape measurement method. There is no limitation on the object's material and texture. We use a projector to project a strip shifting pattern on the object, and a digital camera to record videos of the scene. The distortion of the strip shadow on the object is used to get the object's 3D information. A novel space-time edge finding method is introduced to position the shadow edge accurately. This edge finding method overcomes the effect of inter-reflection and high light. Using this space-time information, we can calculate the pixels' 3D coordinates. To get the 3D shape of an object with black texture, we improve the black strip pattern to a 3-color strip pattern. The bad data are filtered by a post-processing 3D filter, which makes full use of the neighborhoods' geometric constraints and the view point constraint. Meanwhile, our measurement method is fast, regardless of the complexity of the shape.  

傅立叶变换轮廓法用于测量大型三维曲面

叙述了一种用傅立叶变换轮廓法(FTP)来实现的大型三维曲面形状测量系统,并讨论了FTP所能达到的最大测量范围及其在大型三维测量中的优势。  

基于调制度分割的物体轮廓有效测量区域自动识别方法

提出了采用调制度阈值分割技术进行物体轮廓有效测量区域自动识别的一种新方法,克服了投射条纹三维测量技术中由于阴影、条纹断裂、局部镜面反射、暗背景、采样不足以及外来的噪声等因素,使得被测物体表面存在无效测量区域(相位数据不可靠区域)的问题.采用了时域相位去包裹技术,保证了无效区域的相位数据不会影响到有效测量区域的相位数据.与有效测量区域相比,无效区域的调制度明显较低,对调制度直方图进行分析,借鉴图像分割的思想,采用了迭代算法自动求解最佳阈值,辨识物体轮廓测量的有效测量区域和无效测量区域,实现了单视角测量的自动化过程.车灯反射体测量实验证明了这种方法的优越性和可靠性.  

基于位相检测的光学三维轮廓测量方法

三维轮廓测量是当前光学研究领域中非常活跃的一个技术分支,其中位相测量轮廓术(PMP)在求解中严格遵循物像共轭关系,具有较高的测量精度。DMD器件的出现,更推进了PMP技术的发展。本文重点讨论了位相测量轮廓术(PMP)测量中的典型问题,介绍了PMP的应用现状。  

A flexible phase-shifting method with absolute phase marker retrieval

The phase-shifting algorithm is an important and widely employed technology in optical 3D shape measurement. An additional absolute phase marker map is necessary to acquire the absolute phase with traditional phase-shifting algorithm, which not only has a low efficiency but also may not meet certain special requirements of the practical application. In this study, a flexible phase-shifting method, which does not need the additional absolute phase marker map, was developed. A newly designed absolute phase marker was embedded into one of the phase fringe images, and this was retrieved according to its mathematical model; then, the primary phase inside and outside the absolute phase marker region was computed with different methods. Results of experiments show that the retrieval of the marker is easy and flexible, and the phase computation with this novel method is accurate and robust.  

一种基于相位法的彩色三维形貌测量方法

基于相位法的三维形貌测量。提出了一种建立被测物体彩色三维形貌的方法。该方法采用主动光源投射一组光强呈余弦变化的光栅。并由一台黑白CCD工业摄像机对被测物体拍摄从而实现三维形貌的重建；然后对被测物体进行三色光投射。同时黑白工业摄像机拍摄被测物体，通过对所得图片进行分析。实现被测物体的色彩恢复。实验结果表明，该方法能够快速准确的获得被测物体的彩色三维形貌，色彩度误差小，可有效解决黑白工业相机无法进行色彩捕捉这一问题。