计算机断层扫描图像的剖切研究

工业CT扫描通常只能得到某一断面上的二维信息，不能得到被检测物的整体描述，技术人员只能根据获得的系列二维图像在人脑中综合复原为三维结构。因而人们希望能得到直观地、精确地展示被检测物体三维空间结构的ICT直观图像，能得到比二维图像更加丰富的信息。因此断层图像的三维重建在工业无损探伤、天体结构的观察及其它更广泛的领域有着极其重要的实用价值和研究意义。本文提出了一种剖切显示的3D图像处理方法，借助Matlab工具，用软件的方法得到直观的3D图像。     

无损检测中的三维PCB图像自适应平滑技术研究

工业CT系统作为最佳的无损检测技术之一,可以在非接触的条件下快速、准确地发现被检测物体的缺陷部位。尤其近年来新出现的锥束CT,可以生成各向同性的三维图像,更好地对物体进行检测。但是,目前主流的二维图像增强算法,仅能抑制三维图像的层内噪声,无法利用层间信息对图像进一步降噪,尚不能满足三维CT图像增强的需求。根据锥束CT图像特点,将现有的二维自适应平滑算法加以改进,提出了一种三维自适应平滑算法。结果表明：该方法可以利用层间信息,进一步抑制噪声,同时不损失图像的边缘信息,性能明显优于二维平滑算法。     

基于二维图像三维重建的人脸特征提取技术研究

采用基于二维图像的三维重建对人脸特征进行提取.首先应用平行双目视觉原理获取人脸的二维图像,然后对图像进行预处理,消除图像上的噪音点,增强图像,以便提取特征点,对这些二维图像上的特征点进行优化计算,最后得到整体人脸的三维特征点信息.     

Web模式的医学断层图像三维重建

实现了基于Web的医学图像三维重建及显示.用超高速CT扫描获得人体器官的二维图像,基于JavaApplet与JavaApplication编程,采用体绘制法完成二维图像的三维重建与显示.重建实现了在Internet上以Web模式跨平台运行.重建的三维图像能够清晰地显示人体器官的解剖结构,尤其是心脏的整体形态及冠状动脉的走向.用JavaApplet与JavaApplication实现基于Web的医学图像三维重建是可行的,并对三维图像的临床应用起到了推动作用.通过三维重建显示人体器官的立体形态,尤其是冠状动脉的解剖结构,在临床上具有很大的参考价值.     

医学影像三维可视化系统的设计与实现

研究医疗诊断图像.针对计算机断层扫描图像CT和核磁共振图像MRI只能提供人体内部的二维图像,医生们只能凭经验由多幅二维图像去估计病灶的大小和形状,"构思"病灶与其周围组织的三维几何关系,给诊断带来了困难.为了使手术医疗诊断和治疗规划更准确.提出了设计和实现一个交互性的医学图像三维重建和可视化系统.首先给出了医学图像可视化算法原理;然后进行了三维重建可视化系统设计.最后以VC和VTK为开发工具设计程序,实现了CT文件的读取、图像数据的显示和基于MC算法和MS算法的三维模型的重建.仿真结果表明:既可以作为单独三维可视化系统用于医疗诊断,也可以针对不同手术的需要进行功能扩展,证明诊断图像显示更精确,为手术提供了科学手段.     

三维欧氏距离变换快速算法

为了提高三维距离变换在实际应用中的计算效率,提出一种三维快速距离变换算法.首先将三维图像降维为多张二维图像,为每张二维图像设置2个标记数组,并根据标记数组运用围线扫描方法依次计算出每一像素在二维图像上的距离变换;然后依据二维结果计算出所有像素在三维图像中的距离变换.实验结果表明,文中算法实现简单,比已有的边界剥离算法及基于Voronoi图的算法在时间和空间消耗上均有较大的提高,有更好的实用性.     

采用去抖动模糊算法的稠密三维重建

针对无人机在航拍大场景对象进行三维重建时因抖动产生的图像模糊现象,以及二维图像序列经运动恢复结构SFM后得到的点云较为稀疏,可视化差等不足,采用去抖动模糊算法恢复模糊图像的原始图像信息,然后在运动恢复结构的基础上进行基于点云的稠密三维重建,最后对稠密重建后的点云进行泊松表面重建以得到表面致密、均匀的三维模型。实验结果表明,去抖动模糊算法可以有效地提高图像的质量,大场景对象经过基于点云的稠密三维重建后得到的重建效果逼真,可视化强。     

基于单幅图像的三维信息提取

针对单幅图像提取三维信息困难,设计了一种基于单幅图像的三维信息提取算法。该算法首先需要标定摄像机,得到摄像机从三维到二维的成像矩阵M3×4,并计算M3×4的伪逆矩阵M+4×3,其本质是通过最小二乘法求解矛盾方程组;利用M+4×3提取二维单幅图像中的三维信息,再把这些三维信息投影到一个平面上显示出来。实验表明,单幅图像目标物体必须满足共面等约束条件,从而可以对目标物体的三维信息做定性分析(定性视觉)。此外,还对三维空间投影到二维图像的过程进行了理论推导,得出了如果没有足够的先验知识,成像过程不可逆的结论。     

信号博弈的三维重建形变识别算法

现有双目立体视觉算法常常需要双目相机位置固定,在现实应用中,这类算法难以重构空间三维几何关系.为此,本文提出了一种不受位置限制的多视角图像三维重建与形变检测算法.该算法首先采用sift算法获取成对图像的特征点,以获取形变前后比对点对图像的特征信息;其次,利用信号博弈方法确定图像拍摄时相机的空间位置与视角,以准确获取图像的空间位置坐标;再次,依据上述信息完成物体的三维点云重建;进而,利用三维数据信息比对实现物体形变识别.最后,本文利用真实物体的实验,验证了三维重建形变识别算法的有效性.     

从二维图像序列获取三维轮廓的算法及其实现

立体信息的获取是图像分析、计算机视觉中的重要任务之一,国内外学者在这一领域中作了大量的工作。目前获取立体信息的方法主要有接触法、立体视差法、飞行时间测距、结构光测距等,论文提出的新算法是根据摄像机或照相机连续拍到的被测物体图像序列,对每一幅图像进行水平切线分割,找到图像中的切点即图像中的某个水平面与背景的两个交点,依次对二维图像序列中的每一幅图像进行同样的操作,可以获得同一水平面上的若干点,对每个点赋予深度信息,然后将水平面上的点按顺序连接,从而获得图像序列所表示的三维物体的水平截面轮廓。实验结果表明论文提出的算法确实可行、有效。     

等值面的高质量显示算法实现三维物体表面的重建

介绍了一个能有效消除等值面显示中易出现的锯齿状走样现 象,可以生成非常细腻的三维物体表面图象的等值面高质量显示算法。论述了采用体素级的 等值面直接显示算法实现三维物体表面重构的基本方法。     

Circular camera array system for 3‐D displays based on the reconstruction of parallax rays

Abstract— A circular camera system employing an image‐based rendering technique that captures light‐ray data needed for reconstructing three‐dimensional (3‐D) images by using reconstruction of parallax rays from multiple images captured from multiple viewpoints around a real object in order to display a 3‐D image of a real object that can be observed from multiple surrounding viewing points on a 3‐D display is proposed. An interpolation algorithm that is effective in reducing the number of component cameras in the system is also proposed. The interpolation and experimental results which were performed on our previously proposed 3‐D display system based on the reconstruction of parallax rays will be described. When the radius of the proposed circular camera array was 1100 mm, the central angle of the camera array was 40°, and the radius of a real 3‐D object was between 60 and 100 mm, the proposed camera system, consisting of 14 cameras, could obtain sufficient 3‐D light‐ray data to reconstruct 3‐D images on the 3‐D display.     

接触式多关节三维扫描仪研究

论述了拥有自主知识产权的接触式多关节三维扫描仪3DLCS-400的硬件系统和软件系统的基本构成、主要特点和实现方法。在此基础上,研究了接触式三维信息获取中的一些关键技术———数据采集与三维显示的同步、坐标计算和误差校正、三维构型重建。采用基于API函数的异步多线程串行通信和OpenGL三维显示技术,提出了一种修正最小二乘法和基因可变限改进遗传算法相结合的参数标定方法和运用轮廓线的三维散乱数据构型方法。该产品的研制成功填补了国产三维信息获取系统的一个空白。     

浅析三维重建算法

为了将二雏图纸在计算机中自动转换成三维模型并进行交互式显示和各种操作,必须首先从二维图纸中读取所有线条、标注等信息。将这些信息以合适的数据结构进行组织,然后根据这些数据识别相应的几何元素及其位置、尺寸等信息,即进行三维重建。该文对已有的多种三维重建算法进行分类和剖析,归纳出三维重建算法的主要技术难点,并给出了核心的内部数据结构。     

Asymmetric and selective object rendering for optimized Cloud Mobile 3D Display Gaming user experience

Cloud Mobile 3D Display Gaming has been recently proposed where 3D video rendering and encoding are performed on cloud servers, with the resulting 3D video streamed wirelessly to mobile devices with 3D displays. This approach has the advantage of relieving high computation, power and storage requirements of 3D display gaming from mobile devices, while enabling game developers to focus on a single rich version of the game which can be experienced from any mobile device and platform. However, it is challenging to stream 3D video over dynamically fluctuating and often constrained mobile networks. In this paper, we propose a novel technique called Asymmetric and Selective Object Rendering (ASOR) which proves to be more powerful than previous solutions for Cloud based Mobile 3D display gaming. Specifically, this technique will enable rendering engine to intelligently decide whether or not to render an individual object and how good the corresponding texture detail will be if rendered, and the settings can be asymmetric for two views. Thus, unimportant objects can trade quality for reduced bitrate while important objects can remain high quality so that the overall user experience is optimized given certain bandwidth constraints. To quantitatively measure the user experience and bitrate by applying different rendering settings, we develop a user experience model and a bitrate model. We further propose an optimization algorithm which uses the above two models to automatically decide the optimal rendering settings for left view and right view to ensure the best user experience given the network conditions. Experiments conducted using real 4G-LTE network profiles on commercial cloud service with different genres of games demonstrate significant improvement in user experience when the proposed optimization algorithm is applied.     

Virtual viewpoints reconstruction via Fourier slice transformation

We propose a new method of calculating the arbitrary viewpoints for auto‐stereoscopic display. The three‐dimensional (3D) object is first virtually reconstructed in 3D spaces by mapping each pixel with a depth according to the depth mapping. We then calculate the Fourier spectrum of the 3D object by the fast Fourier transformation. The arbitrary viewpoints are reconstructed by “slicing” the 3D Fourier spectrum. To repair “black hole” artifacts, the regions in the background are calculated by advanced boundary in‐painting. Experimental results show the effectiveness and accuracy of the proposed algorithm to calculate viewpoints with arbitrary viewing angles. A comparison is also presented, which indicates that the proposed algorithm is more accurate than conventional method, and the advanced boundary in‐painting can save three quarters of time than the conventional in‐painting method.     

一种基于空间散射元点阵的真三维显示方法

阐述了一种真三维显示方法,方法能够显示对象的物理深度,从而真实地表达第三维。方法基于空间散射元点阵,通过特定算法,生成要显示的对象的平行投影图像。然后,利用透镜折射投影仪光线来获得平行的投射光线,点亮点阵中对应的散射元。在已有方法基础上进行了改进,采用确定性的点阵分布,研究了点阵分布的寻优,并提出利用深度编码产生投影图的方法,最后进行了计算机模拟验证。改进后的方法,在保证了良好的可见度基础上简化了原始方法中的生成投影图的算法,提高了显示效率。     

Analytical model for three-dimensional light-field displays based on voxel construction

Three-dimensional light-field displays (3D-LFDs) can provide viewers with glass-free 3D images. The display effect of reconstructed 3D images is closely related to the number of 3D object points that the 3D display system can construct, which can be regarded as the information quantity of the 3D-LFDs. However, the information quantity presented by a 3D-LFD is limited by fixed hardware parameters such as display panels and optical components. It is difficult to present an ideal 3D visual experience with the increase in display depth. In this paper, an analytical model based on voxel construction for 3D-LFDs is proposed, which can estimate the information quantity that a 3D-LFD can reproduce. The variation regularity of information quantity with display depth is analyzed and the influence of hardware parameters on display effect is discussed. With the proposed strategies, the display effect can be improved in a targeted manner without blurring and aliasing by adjusting the hardware parameters in display systems and matching the information quantity at different display depths.