A Method for Obtaining Three-dimensional Images with Visual Reality of Real Objects

1IntroduCtionThree-dimenShaalsensingis0fgreatimportanceinr0boicvision,aut0maticprocessing,b~dicineandcomPuter'animatdri-OPticalthree-dimensionalsenSngaregettingmoeandmoeimportantbecauseofitsadvantagesofnon-contact,highprecisionandaut0maticcontr0.TheoPticalthree-dimenAnalsensingmethodincludelasertriangulati0n['-'],Moreprofiboetry['1,FourierTransf0rmProfiIomtry(m)['J,andPhaseMeasurementProfilometry(PMP)[6].Exceptlasertriangulatdri,theabovemethOdsarefitforthree-dimensi0nalsensing0nlyfrOI…     

Computer-Generated Holograms Based on the Three-Dimensional Fourier Spectrum

A method to synthesize a computer-generated hologram (CGH) of real-existing objects from projection images is proposed. Different from other similar methods, our method enables the synthesis of a CGH with only one-dimensional (1-D) mechanical scanning of the objects. Our method is connected with the three-dimensional (3-D) Fourier spectrum of the objects by the 3-D central slice theorem (CST). Two efficient recording techniques for projection images and numerical experiments to verify our principle is discussed. A comparison between the two techniques is also presented from the viewpoint of diffraction efficiency. © 2005 The Optical Society of Japan     

Three-Dimensional Information Acquisition Using a Compound Imaging System

The TOMBO (thin observation module by bound optics) system is a compound imaging system inspired by a biological visual system. Various interesting features can be utilized in the applications of the TOMBO system: in this paper, we present an effective method for three-dimensional information acquisition. An image captured by the TOMBO system is composed of multiple images observed from several viewpoints. Distance between the TOMBO system and an object can be estimated using disparity of the captured images. A new method for estimation of the object distance is introduced. In the experiment, multiple object distances can be successfully estimated by the proposed method. Using the obtained distances for image reconstruction, we can generate a composite image focussing on multiple objects.     

Holographic three-dimensional display synthesized from three-dimensional fourier spectra of real existing objects

A method of synthesizing computer-generated holograms of real existing objects is proposed that is based on a series of projection images of an incoherently illuminated object recorded from different perspectives. In accordance with the principles of computer tomography, the three-dimensional Fourier spectrum of the object is calculated by use of several projection images. A method of calculating a Fresnel hologram from the three-dimensional Fourier spectrum is proposed. Experimental results in the form of a computer simulation and optical reconstruction are presented.     

Acceptable distortion and magnification of images on reflective surfaces in an augmented reality system

In this paper, we investigated the consistency of visual perception for the change of reflection images in an augmented reality setting. Reflection images with distortion and magnification were generated by changing the capture position of the environment map. Observers evaluated the distortion and magnification in reflection images where the reflected objects were arranged symmetrically or asymmetrically. Our results confirmed that the observers’ visual perception was more sensitive to changes in distortion than in magnification in the reflection images. Moreover, the asymmetrical arrangement of reflected objects effectively expands the acceptable range of distortion compared with the symmetrical arrangement.     

Optical measurement network for large-scale and shell-like objects

An optical measurement method for large-scale and shell-like objects is proposed and is verified by experiments. The underlying concept is a model-based optical measurement network consisting of multinode three-dimensional (3D) sensors. To achieve this, a synthetic calibration method is presented to enable the measurement. A phase-aided active stereoscopy is thus applied to each node sensor for acquiring partial range images from different viewpoints. The multiple range images are then registered to obtain a 3D reconstructed model, which is compared with the computer-aided design (CAD) model to quantitatively reveal the differences between the two models. Experiment results are also presented to validate the proposed approach.     

水中物体的光学三维形貌测量的研究

提出了一种对水中物体进行光学投影式表面三维形貌测量的新方法。通常的测量方法都是假设摄像机和被测物体都处于空气中,测量水中物体时,由于光在空气、水分界面上发生折射,投射到被测表面的光条纹图像发生扭曲,从而给三角测量法带来误差。新方法可以精确测量出水中被测物表面的三维坐标并计算出物体的几何尺寸,实验验证了该方法的有效性。考虑折射后,该测量类似于在空气环境中的测量。采用的极线约束及亚像素技术,提高了测量精度和速度。     

一种三维全息图的数字化实现方法

提出一种实现三维显示的新方法,从两步法彩虹全息基本原理出发,通过分区域分幅的方式对多视角图形的波前进行数字化编码,获得夫琅和费光场分布,在位相型硅基液晶空间光调制器上按视角顺序输入该信息,利用透镜的傅里叶变换特性再现多视角子图像,干涉法逐区域拼接获得完整三维图像.最后通过实验获得了三维图像样品,验证了该方法.本方法可成为三维显示的重要技术手段.     

复杂刚性运动物体的高精度三维测量算法

基于相移法的三维形貌重建精度高,对环境噪声和阴影等不敏感,但由于多幅条纹解相位,难以应用于动态物体的三维测量中,为此,提出了一种新的算法.基于Harris算法提取刚性运动棋盘格的角点,确定相邻两帧采集条纹图像之间的像素偏差并校正采集条纹图像;根据投影仪和摄像机的标定参数建立投影图像和采集图像之间的空间变换矩阵,并根据变...     

Computational integral imaging reconstruction scheme of far 3D objects by additional use of an imaging lens

In this paper, we propose a novel performance-enhanced computational integral imaging reconstruction (CIIR) scheme by additional use of an imaging lens. In the proposed scheme, elemental images can be obtained by using a simultaneous pickup scheme of far three-dimensional (3D) objects from the lenslet array in both real and virtual image fields. And additional imaging lens produces an image shift effect of 3D objects located far away from the lenslet array and improve the visual quality of reconstructed images in CIIR by overcoming limitation of pickup range in integral imaging. To show the usefulness of the proposed system, some experiments are carried out for real 3D objects and its results are presented.     

Three-dimensional visualization of objects in scattering medium using integral imaging and spectral analysis

This paper presents a three-dimensional visualization method of 3D objects in a scattering medium. The proposed method employs integral imaging and spectral analysis to improve the visual quality of 3D images. The images observed from 3D objects in the scattering medium such as turbid water suffer from image degradation due to scattering. The main reason is that the observed image signal is very weak compared with the scattering signal. Common image enhancement techniques including histogram equalization and contrast enhancement works improperly to overcome the problem. Thus, integral imaging that enables to integrate the weak signals from multiple images was discussed to improve image quality. In this paper, we apply spectral analysis to an integral imaging system such as the computational integral imaging reconstruction. Also, we introduce a signal model with a visibility parameter to analyze the scattering signal. The proposed method based on spectral analysis efficiently estimates the original signal and it is applied to elemental images. The visibility-enhanced elemental images are then used to reconstruct 3D images using a computational integral imaging reconstruction algorithm. To evaluate the proposed method, we perform the optical experiments for 3D objects in turbid water. The experimental results indicate that the proposed method outperforms the existing methods.     

利用CCD图像的灰度梯度实现物体三维测量

提出了一种利用CCD单目图像的灰度梯度测量三维表面的方法——灰度梯度法。巧妙地运用中间变量，找到灰度梯度与聚焦像表面梯度之间的映射关系，将灰度约束方程转变为可求解的一元方程，从而解出聚焦像表面的深度信息。利用聚焦像表面与物体间的几何光学的约束以及它们之间的空间共轭对称关系，将该三维表面变换到实际三维尺寸，以达到三维测量的目的。最后对影响该测量系统的误差进行了分析。该方法克服了传统的光切法因过多冗余图像而使测量效率低的缺点，且该方法约束条件容易实现。对球体和柱面体的试验误差率分别为6．0％和4．85％，显示出该方法在一定范围内是有效的。     

基于单摄像机的昆虫自由飞行参量三维重构

研究昆虫飞行的三维空间运动参量需要对二维图像进行重构,传统的重构方法是采用两个或者多个相机从不同角度拍摄以获得同时刻不同角度的图像。介绍了一种采用单一相机完成三维重构的方法。通过在单相机镜头前面附加四块两两平行的平面镜组来获得三维信息,该装置可以在同一照片上获得物体两个角度的观察图像,等效于用两个高速摄影仪对昆虫的飞行进行拍摄。分别标定出每个等效摄像机的参量,根据机器视觉原理进行三维重构。实现了用单个相机完成昆虫自由飞行状态的翅膀三维参量重构过程,避免采用多个相机的需要增加复杂同步电路以及引起的高额费用,同事也克服了过去基于单相机的三维重构需要增加某些假设所引起的与真实飞行的差异。     

Regeneration of elemental images in integral imaging for occluded objects using a plenoptic camera

In this Letter, we propose an elemental image regeneration method of three-dimensional(3D) integral imaging for occluded objects using a plenoptic camera. In conventional occlusion removal techniques, the information of the occlusion layers may be lost. Thus, elemental images have cracked parts, so the visual quality of the reconstructed 3D image is degraded. However, these cracked parts can be interpolated from adjacent elemental images. Therefore, in this Letter, we try to improve the visual quality of reconstructed 3D images by interpolating and regenerating virtual elemental images with adjacent elemental images after removing the occlusion layers. To prove our proposed method, we carry out optical experiments and calculate performance metrics such as the mean square error(MSE) and the peak signal-to-noise ratio(PSNR).     

红外图像伪彩色编码和处理

利用红外热成像系统可将物体的热分布转化为可视图像，并在监视器上以灰度级或伪彩色显示出来，从而得到被测目标的温度分布场。根据热成像测温原理以及红外图像的特点，在对室温热成像系统研究的基础上，对红外图像伪彩色编码进行了研究，提出一种新的伪彩色编码方法，即自动阈值法。利用自动阈值法可以在室温环境下，对目标的温度及其分布进行测量。在TMS320C6202和FPGA室温热成像系统中对提出的方法进行了验证。实验结果表明，该方法可使红外图像层次分明，容易分辨出不同的温度区域。     

Stereoscopic imaging through scattering media

We develop and experimentally test a method for three-dimensional imaging of hidden objects in a scattering medium. In our scheme, objects hidden between two biological tissues at different depths from the viewing system are recovered, and their three-dimensional locations are computed. Analogous to a fly's two eyes, two microlens arrays are used to observe the hidden objects from different perspectives. At the output of each lens array we construct the objects from several sets of many speckled images with a previously suggested technique that uses a reference point. The differences of the reconstructed images in both arrays with respect to the reference point yield the information regarding the relative depth among the various objects.     

A simultaneous in- and out-of-plane displacement measurement method

A method is presented that allows real-time three-dimensional displacement maps to be obtained for deformable objects using a single color camera and a color fringe projector. The acquired images have speckle and fringe information embedded in them, which are separated using the R, G, and B color signals from a color CCD camera to permit the independent use of a two-dimensional digital image correlation to obtain the x- and y-direction displacements and fringe projection to obtain the displacement in the z direction.     

基于仿射近似从序列图像重建目标三维结构

从序列图像重建目标三维结构是摄影测量学和计算机视觉的研究热点。针对传统算法中精度与计算量的矛盾,提出一种基于仿射近似的新算法,首先用仿射三线性张量合成序列图像中的缺失图像点,重新建立图像测量矩阵,然后用仿射矩阵分解从图像特征直接获得目标三维结构的初始值,最后用基于“R-T”模式的光束法平差进行优化。仿真数据和真实图像实验表明,新算法精度高、稳定性好,有效解决了传统算法中精度、算法复杂性与结果数值稳定性的矛盾,为序列图像三维解析中的关键技术问题提供了解决方案。算法可广泛应用于航空测绘、工业检测、虚拟现实、动画制作以及军事侦察等领域。     

新型自动立体显示背光板的光学设计

立体显示技术的研究主要是解决虚拟现实领域的三维视觉问题。自动立体显示是不需要配戴特殊眼镜的,使用一个二维平面空间显示屏显示至少一对满足双眼视差的立体图像。当人的双眼接受到具有视差的立体图像对时,在视网膜上形成视差像,经大脑神经系统的融合,从而产生深度感。提出了一种全新的实现自动立体显示的折射式方法,设计了基于此方法的一种新型折射式的、结构简单的、通过透射显示屏(如液晶显示屏)实现自动立体显示的背光系统。根据视差立体显示参量模型,建立了光学系统的结构参量以及分析了光学材料的性质对实现立体显示的影响,并运用先进的光学设计软件进行设计、模拟。     

Use of focus stacking and SfM techniques in the process of registration of a small object hologram

In this Letter, a method for shape visualization of small objects(microscopic) in the form of a hologram is presented. It consists of a standard optical set-up for small object registration(i.e., stereoscopic or biological microscope). The focus stacking technique is used to obtain a series of images with increased depth of field and on them a shape reconstruction procedure(structure from motion, SfM) is made. With use of a dense cloud of points, a sequence of parallax-related images suitable for Geola's digital holographic printing is generated. The holographic printer produces single-parallax holographic(full three-dimensional) images of real or virtual objects.