一种新的360°三维轮廓术

提出了运用相移技术的光刀投影式测量３６０°回转物体三维轮廓的新方法。该方法对投影光刀引入正弦分布光场,利用相移技术对光刀投影狭缝进行相位计算,可得出各点的包裹相位分布,然后再利用光刀投影测量原理得到的高度信息对相位进行去包裹处理,从而得到具有较高精度的相位测量结果。最后根据相位与物体高度的几何关系,得到物体的三维轮廓数据。文中详细介绍了这一技术的原理及实验结果     

用于动态测量的双通道光学相位测量轮廓术

提出了利用编码光两个采样值实现相位测量轮廓术的原理。设计了一种偏振分光双通道测量系统，实现了两个采样值的同时记录，因而实现了动态测量，拓展了相位测量轮廓术的应用范围。文中给出了实验结果。     

探测器像素尺寸对PMP测量精度的影响研究

以阶跃型反射率分布为例，分析了像素尺寸对相位测量轮廓术（PMP）测量精度的影响情况。仿真结果表明相位测量误差大小随感光单元覆盖的相位范围增加而增加，即采用高分辨率探测器可以得到高的测量精度；相位测量误差大小与阶跃在感光单元上的位置有关，存在导致最大误差的位置，并且该位置与阶跃相对幅值有关；相位测量误差大小随阶跃相对幅值增大而增大，偏向反射率高的方向。研究结果为PMP测量系统设计中图像探测器选择、测量精度评价提供了依据。     

双频相位测量轮廓术及其误差分析

提出一种双频相位测量轮廓术，利用这一技术。在相位恢复过程中，对有断点及边界区域也能得到正确的去包裹相位值，把这一技术用于三维面形测量中，得到了较好的实验结果。最后，分析实验产生误差的原因。     

一种校正相位测量轮廓术量化误差的算法

为了减小相位测量轮廓术中因数字化设备内部结构的量化处理过程引起的相位量化误差,提高相位测量精度。针对相位测量精度要求较高且表面凹凸变化不大的被扫描物体提出了一种能够有效校正相位测量轮廓术量化误差的算法,测量相位中的每一个像素点利用其相邻像素点进行校正。实验结果显示,校正之后,相位量化误差标准差减小了41.38%,相位测量的精度得到了提高。     

相位测量轮廓术中三维坐标校准新方法

提出了一种新的用于相位测量轮廓术中的三维坐标校准方法。该方法用一个含有三个虚拟校准平面的标准块代替传统相位测量轮廓术校准方法中使用的标准平面，每个虚拟校准平面由多个高度相同但空间离散分布的子区域组成，相应的连续相位恢复是通过一个迭代过程实现的，同时各个子区域还被用于横向坐标的校准。由于各个虚拟校准平面间高度是垂直变化的，传统的相位展开不能得到正确的相对位置关系，基于等效波长概念，提出了一种准确的虚拟校准平面连续相位间相对位置恢复的办法。此校准方法的特点是：在校准过程中不需要标准平面的多次精确平移；仅需要一次测量就可以完成高度和横向坐标的同时校准。文中给出的实验结果说明了该校准方法的有效性和可行性。     

基于微分法的新傅里叶测量轮廓术

在傅里叶测量轮廓术中,为了得到真实相位值,必须进行相位解包裹处理的繁锁过程,为此提出一种可以直接获得真实相位值的新算法.这种算法的原理是空域中的微分(一阶)等效于频域中乘以一个线性因子,由此得到相位微分与光强的关系,求出相位的微分值后将其积分就获得相位的真实值.计算机仿真显示该方法确实有效可行.     

抑制相位测量轮廓术饱和误差相位融合算法

在相位测量轮廓术中,由于被测物体表面反射率过大,导致照相机捕获的图像中部分像素点强度值超过照相机的最大量化值,即光强度饱和。分析了光强度饱和引起的相位误差,提出一种相位融合算法。该算法通过查找归一化后的最大调制强度,提取其对应的相位,并将该相位作为三维重建的最终相位。实验结果表明,在理想情况及测量系统存在Gamma畸变时该算法均能有效地修复饱和误差。当测量系统存在Gamma畸变时,校正后相位误差均方根值相对于传统技术减小了58.86%。     

彩色多通道光栅投影轮廓术

研究了一种双通道光学相位测量轮廓术。利用彩色空间中红色与蓝色互相独立、互不干扰的特性,将两个相位相反的线性周期变化的光栅分别放在红以与蓝色通道,形成彩色双通道投影光栅。用彩色ＣＣＤ获取图像,并和图像采集卡将图像送入计算机。从彩色图像的红色与蓝色通道可分别获得两个互相反相位的线性周期光栅的调制图。在一次采样中即可获得两个通道的测量结果,因而特别适用于动态测量。     

相移阴影莫尔条纹正交化解调技术

提出一种基于克莱姆正则化分析法的三帧自标定相移阴影莫尔三维轮廓技术.该技术首先采用移动光栅的方法获得相移条纹图,然后通过不同帧相移条纹图相减去除条纹图背景,进而结合克莱姆正交化法和最小二乘法,发展了一种相位解调方法,提取了测量相位.以五步Harlharan算法为参考,用不同算法对同一物体表面进行测量.结果表明,相对于典型的三步相移法和主量分析方法,提出的方法测量得到的相位误差最小(0.5rad),且简化了测量过程.     

Watermarking of three-dimensional objects by digital holography

We present an optical method for information watermarking of three-dimensional (3D) objects by digital holography. A hidden image is embedded by double phase encoding in a phase-shift digital hologram of the 3D object. We decode the watermarked hologram to reconstruct the hidden image and the 3D object. We use either the entire hologram or a part of it to decode the hidden image. Experiments are presented to illustrate the ability to recover both the 3D object and the decoded hidden image. Digital holograms of the 3D object are obtained by optical experiments. The watermarking process, 3D object reconstruction, and hidden image recovery are performed digitally. To the best of our knowledge, this is the first report of 3D object watermarking by use of a phase encoding technique and digital holography.     

Three-dimensional polarimetric integral imaging

A three-dimensional (3D) polarimetric image sensing and display technique based on integral imaging is proposed. Three-dimensional polarization distribution of reflected light from a 3D object can be measured as elemental image arrays by a rotating linear polarizer. After the measurement of the polarization of the 3D object, the 3D polarimetric object can be reconstructed optically by displaying the polarization-selected elemental images in spatial light modulators with two quarter-wave plates. Experimental demonstration of 3D polarimetric imaging of a 3D object attached to two orthogonal linear polarizers is presented. To the best of our knowledge, this is the first report on 3D polarimetric sensing imaging and 3D optical reconstruction by integral imaging.     

Spatial Position Detection of Three-Dimensional Objects by Effective Three-Dimensional Correlation Based on Fourier Transform Profilometry

Spatial position detection of a three-dimensional (3D) object by a correlator based on Fourier transform profilometry is discussed. The presence of the 3D object and its precise spatial position can be recognized by the correlator using the position and phase of the correlation peak. The spatial position is obtained by the relative displacement from the position where the reference object is originally placed. The characteristic of the correlator with respect to the moving direction of a 3D object is experimentally verified. Effects of the baseline factor on 3D object recognition are also investigated.     

Real-time spatiotemporal division multiplexing electroholography for 1,200,000 object points using multiple-graphics processing unit cluster

Computationally, the calculation of computer-generated holograms is extremely expensive, and the image quality deteriorates when reconstructing three-dimensional(3 D) holographic video from a point-cloud model comprising a huge number of object points. To solve these problems, we implement herein a spatiotemporal division multiplexing method on a cluster system with 13 GPUs connected by a gigabit Ethernet network.A performance evaluation indicates that the proposed method can realize a real-time holographic video of a3 D object comprising ~1,200,000 object points. These results demonstrate a clear 3 D holographic video at32.7 frames per second reconstructed from a 3 D object comprising 1,064,462 object points.     

集成成像大纵深物体的三维形貌获取技术

为了满足现代工业所需的大纵深物体的三维形貌获取需求,解决传统结构光三维形貌获取技术纵深较小的问题, 借助集成成像这种阵列式多视点获取技术,构建了基于集成成像的大纵深物体的三维形貌获取技术。从集成成像原理出发,分析了集成成像三维物点和同名像点之间的关系,得到集成成像光学获取系统参数和三维物体纵深极限之间的关系。在此基础上,利用相机和电动平移台构建了扫描式相机集成成像三维形貌获取系统,并对纵深从600 mm到3 600 mm相对独立的2个物体构建的大纵深三维物体进行了形貌获取。光学实验结果显示,该集成成像大纵深物体三维形貌获取技术能够单次获取纵深为3 600 mm的三维物体的三维形貌,为大纵深物体的三维形貌获取提供了技术支持。     

Neural network for three-dimensional object recognition based on digital holography

We present a two-layer neural network for processing of three-dimensional (3D) images that are obtained by digital holography. The network is trained with a real 3D object to compute the weights of the layers. Experiments are presented to illustrate the system performance. The system is designed to detect a 3D object in the presence of various distortions. As an example, experiments are presented to illustrate how the system is able to recognize a 3D object with 360 degrees out-of-plane rotation.     

基于主分量分析法的小波域三维目标序列图像隐藏技术

针对在一幅载体图像中隐藏三维目标序列图像的问题,本文利用主分量分析法获取三维目标的本征图像,将本征图像的小波域系数嵌入到载体图像的小波域系数中,利用分解系数和提取得到的本征图像重构出三维目标的系列图像.本文所提出的方法不是直接存储目标图像,而是存储能够反映三维目标特征的一组本征图像.研究结果表明,该方法有效地将三维目标的特征隐藏在了载体图像中,隐藏信息量大. 关键词： 信息隐藏 三维目标 主分量分析 小波变换     

三维面形测量数据的计算全息可视化

提出利用计算机制全息进行三维面形测量数据立体重现的技术。首先利用三维面形测量技术同时获取三维物体的强度和距离像；然后根据三维面形测量数据，设计和制作菲涅耳计算全息图；最后将计算全息和光学全息相结合，以菲涅耳计算全息图的光学再现像为对象，记录光学像全息。这样既解决了计算机制全息术中真实三维物体立体信息数据捕捉的问题，又为三维面形检测提供了一个行之有效的立体重构技术。给出了这种方法的原理、计算全息的设计、制作方案和实验验证结果。     

Three-dimensional object recognition from digital Fresnel hologram by wavelet matched filtering

We propose and demonstrate a digital holographic technique for 3D object recognition and classification. One Fresnel digital hologram of each of the 3D objects to be classified is recorded. The electronic holograms are processed digitally to retrieve 3D object information as 2D digital complex images. We use this method to classify four physical objects in a 3D scene into two classes. Results are presented from an experiment to demonstrate the proof of the concept.     

A novel three-dimensional digital watermarking scheme basing on integral imaging

A novel integral imaging-based three-dimensional (3D) digital watermarking scheme is presented. In the proposed method, an elemental image array (EIA) obtained by recording the rays coming from a 3D object through a pinhole array in the integral imaging system is employed as a new 3D watermark. The EIA is composed of a number of small elemental images having their own perspectives of a 3D object, and from this recorded EIA various depth-dependent 3D object images can be reconstructed by using the computational integral imaging reconstruction (CIIR) technique. This 3D property of the EIA watermark can make a robust reconstruction of the watermark image available even though there are some data losses in the embedded watermark by attacks. To show the robustness of the proposed scheme against attacks, some experiments are carried out and the results are discussed.