电容层析成像系统三维图像重建及其在两相流体积测量中的应用研究

探讨了电容层析成像系统中利用二维断层图像进行三维表面重建，并由三维图像求取两相流中离散相体积和观察其空间位置的方法。首先对二维断层图像序列进行轮廓抽取和细线化，然后进行轮廓匹配和轮廓插值并进行表面重建；最后利用三维图像求取两相流中离散相体积。初步的仿真结果表明，使用的三维重建算法简单，重建精度高，成像速率快，可以方便地观察离散相空间位置和计算出离散相体积。     

序列图像的三维重构方法

依据光学显微镜的多幅序列图像,通过比较多个层面上的图像,并根据光学显微镜的成像特性设计一种实体重构方法,完成三维图像的重建显示分析技术研究。提出以软件处理技术实现对多幅断层图像进行三维重建分析,较好地实现通过解卷积去除离焦平面的模糊图像,进而对多幅序列图像进行三维重建分析,得到物体表面的完整造型。     

基于医用X-CT的三维重建系统研究

根据CT图像特点,运用计算机图形、图像和三维可视化技术,开发了一套基于医用X-CT的三维重建原型系统,实现对二维有序CT的浏览、图像分割及重建图像显示等操作.介绍了系统的结构和各种算法的实现.试验结果表明,该系统满足临床辅助诊断和手术计划制定的要求.     

CT数据三维重建及可视化技术的研究

根据CT图像特点,运用计算机图形、图像和三维可视化技术,开发了一套基于医用X-CT的三维重建原型系统,实现对二维有序CT的浏览、图像分割及重建图像显示等操作.介绍了系统的结构和各种算法的实现.试验结果表明,该系统满足临床辅助诊断和手术计划制定的要求.     

基于机器人的管道内壁三维重建技术研究

该文主要研究根据排水管道的二维激光扫描信息重建其三维内壁图像的技术与应用。提出了携带二维激光扫描仪的管道机器人对管道内壁进行数据采集及处理的方案;探讨管道内壁的三维数据重建算法,即利用机器人在管道中相对于水平面的二维倾角信息和管道内壁点云的圆柱形几何特征来计算机器人在管道中的姿态,进而得到机器人坐标系相对于全局坐标系的变换矩阵,把不同视点的点云转换到统一的全局坐标系中,对点云进行匹配。实验验证了该文提出的管道三维重建算法的可行性,对于检测管道内部工况具有重要的理论与应用价值。     

基子CT图像快速成型数据的构建方法

本文针对医学CT图像数据,提出了由CT图像构建快速成型数据的建模方法,确定了CT图像处理方案,即通过对断层图像的预处理、滤波处理、数据提取,生成断层图像轮廓,继而通过对轮廓优化和轮廓冗余数据去除,得到用于三维重建的二维轮廓数据,并在此基础上构造出可直接用于快速原型制造的三维STL数字模型.本文所提出的方法能够大大提高快速医学模型的构建速度.     

生物体内部结构三维显微成像技术研究

概述了生物体内部结构的几种传统的成像技术 ,介绍了一种新的生物体内部结构三维显微成像方法。该方法对生物体作连续切片 ,由 CCD显微摄像系统获取切片的序列图像 ,然后由计算机进行三维图像重构 ,最终得到生物体内部结构的三维显微图像     

基于工业计算机断层成像技术的三维CAD模型重构方法

为解决复杂形状产品的三维计算机辅助设计模型的重构难题,提出了一种基于工业计算机断层成像技术的三维计算机辅助设计模型的重构方法.首先用工业计算机断层成像技术对产品进行扫描,得到产品切片图像,然后通过切片图像获取体数据;在采用高斯滤波对体数据进行预处理后,使用移动立方体算法重建三维表面,并用顶点删除法和二次误差测度算法简化三维表面;在采用Laplacian算法平滑三维表面后,将三维表面模型保存为STL格式的文件;最后,将STL格式的文件导入到UG中,重构出产品的三维计算机辅助设计模型.实际应用验证了该方法的有效性和正确性.     

Pro/E曲面造型技术的牙齿三维模型重建

提出基于曲面造型功能的三维模型重建方法,并应用Pro/E软件实现口腔牙齿的CT(Computed Tomography)影像的三维实体重建,生成町编辑的牙齿三维实体模型.该方法综合使用Photoshop、AutoCAD、Pro/E图形图像处理软件,主要实现过程为:通过螺旋CT获取断层图像;用Photoshop去除噪点,提取断层轮廓线;用AutoCAD样条拟合断层矢量图;用Pro/E曲面造型技术形成三维实体模型的重建.该模型与螺旋CT三维重建影像比较,具有更好的几何相似性与还原性.     

用IDL实现基于CT图像的三维表面重建

利用计算机断层(CT)图像进行人体组织三维重建,在医学、人体科学等领域拥有非常广阔的应用前景.IDL是近年来被广泛应用于医学图像处理的交互式数据语言.本文结合一组CT图像,介绍了一种用IDL语言实现CT图像形态学边缘检测、轮廓提取和三维表面重建的方法.并采用IDL中事件驱动的程序结构,设计了三维可视化程序.     

基于贝叶斯自适应估计的光子计数集成成像

针对光子数极少环境下三维目标的重构问题,基于光子计数集成成像系统提出了一种贝叶斯自适应估计方法,来提高三维目标深度切片的重构质量。首先,通过光子计数集成成像系统获得一系列光子计数元素图像。接着,从光子计数过程的泊松分布出发,利用集成成像系统中对于同一个目标像素的多次采样特性,引入了局部自适应均值因子,从而建立起元素图像像素光子数估计的单参数后验概率模型。最后,通过后验概率模型的均值计算获得更新后的光子计数元素图像,并基于光束可逆原理重构出深度切片图像。实验结果表明:采用该方法在场景的两个深度处重构的切片图像相比传统贝叶斯重构图像的峰值信噪比提高了7.4dB和8.5dB,极大地提升了微弱光三维目标的重构质量。     

基于激光扫描的密集泡状流三维重建与优化

为测量密集气液泡状流的流动形态及参数,建立了基于激光扫描的三维可视化测量系统。采用片状激光结合旋转正多边形棱镜实现对流场的光学扫描,高速摄像机采集扫描切片图像,首先对图像进行预处理。针对扫描成像中产生的切片重复曝光问题,提出二阶微分平均卷积优化算法,该方法不仅可以有效提取多切片图像中重复曝光的特征点,而且可以去除冗余及噪声信息。实验结果表明,针对分散相遮挡的密集泡状流,基于激光扫描可完整重建其三维结构,二阶微分优化算法可以有效降低重建畸变影响,重建后体积含气率的相对误差优于6%。激光扫描方法非侵入、重建精度高,具有传统方法不可比拟的优势。     

基于锥束CT切片图像的复杂零件三维表面重构

根据锥束CT切片图像的特点，提出了一种面向复杂零件的三维表面重构新方法：首先采用3D亚体素边缘检测算法提取序列切片图像的高精度封闭轮廓，并重构出切片轮廓的拓扑信息，然后采用一种改进的基于截面属性的轮廓分割算法得到若干组局部结构轮廓集，最后对这些轮廓集进行叠加与拼合，形成零件的整个三维表面。实验结果表明，该方法分割轮廓准确，稳定性好，对具有复杂内外结构的零件，可确保其重构结果的拓扑正确性。     

电容层析成像三维成像算法研究与软件设计

为了研究循环流化床中气体 -固体的分布规律 ,基于电容层析成像得到的二维断面浓度分布 ,利用一种线性差值算法 ,构建固体颗粒的三维浓度分布。三维图像的显示采用 C 语言和 Open GL系统完成 ,并将该算法用于循环流化床中 ,结果清楚地显示了气泡的发展变化过程。     

Metrological challenges for reconstruction of 3‐D microstructures by focused ion beam tomography methods

The development of combined focused ion beam and scanning electron microscopes has enabled significant advances in the characterization of the 3‐D structure of materials. The repeated removal of thin layers or slices with an ion beam and imaging or mapping the chemical or crystallographic structure of each slice enables a 3‐D reconstruction from the images or maps. The accuracy of the reconstruction thus depends on the accuracy with which the slice thickness is measured and maintained throughout the process, and the alignment accuracy of the slices achieved during acquisition or by postacquisition corrections. A survey of papers published in this field suggests that the reconstruction accuracy is not often considered or reported. Using examples from examination of the 3‐D structure of hardmetals, issues affecting the accuracy of slice thicknesses and image realignments are examined and illustrated and potential errors quantified by the use of fiducial markers and the expected isotropy of the hardmetal structure itself.     

Surface imaging microscopy using an ultramiller for large volume 3D reconstruction of wax- and resin-embedded tissues

Three-dimensional reconstruction of large tissue volumes using histological thin sections poses difficulties because of registration of sections, section distortion, and the possibility of incomplete data set collection due to section loss. We have constructed an integrated surface imaging system that successfully addresses these problems. Embedded tissue is mounted on a high precision XYZ stage and the upper surface is iteratively: (i) stained to provide an effective optical section, (ii) imaged using a digital camera, and (iii) removed with an ultramiller. This approach provides for the reconstruction of high-quality 3D images by inherently preserving image registration, eliminates section distortion, thus removing the need for complex realignment and correction, and also ensures full capture of all image planes. The system has the capacity to acquire images of tissue structure with voxel sizes from 0.5 to 50 mum over dimensions ranging from micrometers to tens of millimeters. The ultramiller enables large samples to be imaged by reliably removing tissue over their full extent. The ability to visualize key features of 3D tissue structure across such a range of scale and resolution will facilitate the development of a greater understanding of the relationship between structure and function. This understanding is essential for better analyses of the structural changes associated with different disease states, and the development of structure-based computer models of biological function.     

基于ICT图象的实体建模研究

本文研究了基于 Ｉ Ｃ Ｔ 切片图象的实体建模技术，重构了产品的实体模型．针对装配体 Ｉ Ｃ Ｔ 切片图象的特点，提出了切片采样，精确识别轮廓控制点的算法，基于简单环的内外边界识别，实体建模，基于二维图形特征和上下切片特征之间的关系识别三维特征，通过以上方法提高了实体建模的精度。     

En bloc optical sectioning of resin-embedded specimens using a confocal laser scanning microscope

Reconstruction of 3D structures of specimens embedded for light or electron microscopy is usually achieved by cutting serial sections through the tissues, then assembling the images from each section to reconstruct the original structure or feature. This is both time-consuming and destructive, and may lead to areas of particular interest being missed. This paper describes a method of examining specimens which have been fixed in glutaraldehyde and embedded in epoxy resin, by utilising the autofluorescence preserved or enhanced by aldehyde fixation, and by using a confocal laser scanning microscope to section optically such specimens in the block down to a depth of about 200 μm. In this way, the accurate estimation of the depth of particular features could be used to facilitate subsequent sectioning at the light microscope or electron microscope level for more detailed studies, and 3D images of tissues/structures within the block could be easily prepared if required.     

Reconstruct: a free editor for serial section microscopy

Many microscopy studies require reconstruction from serial sections, a method of analysis that is sometimes difficult and time-consuming. When each section is cut, mounted and imaged separately, section images must be montaged and realigned to accurately analyse and visualize the three-dimensional (3D) structure. Reconstruct is a free editor designed to facilitate montaging, alignment, analysis and visualization of serial sections. The methods used by Reconstruct for organizing, transforming and displaying data enable the analysis of series with large numbers of sections and images over a large range of magnifications by making efficient use of computer memory. Alignments can correct for some types of non-linear deformations, including cracks and folds, as often encountered in serial electron microscopy. A large number of different structures can be easily traced and placed together in a single 3D scene that can be animated or saved. As a flexible editor, Reconstruct can reduce the time and resources expended for serial section studies and allows a larger tissue volume to be analysed more quickly.     

Observation of three-dimensional internal structure of steel materials by means of serial sectioning with ultrasonic elliptical vibration cutting

A three-dimensional (3D) internal structure observation system based on serial sectioning was developed from an ultrasonic elliptical vibration cutting device and an optical microscope combined with a high-precision positioning device. For bearing steel samples, the cutting device created mirrored surfaces suitable for optical metallography, even for long-cutting distances during serial sectioning of these ferrous materials. Serial sectioning progressed automatically by means of numerical control. The system was used to observe inclusions in steel materials on a scale of several tens of micrometers. Three specimens containing inclusions were prepared from bearing steels. These inclusions could be detected as two-dimensional (2D) sectional images with resolution better than 1 μm. A three-dimensional (3D) model of each inclusion was reconstructed from the 2D serial images. The microscopic 3D models had sharp edges and complicated surfaces.