基于多幅未标定图像的三维度量重构

提出了一种基于多幅未标定图像，恢复场景三维几何的优化矩阵分解算法，该算法先通过迭代逼近得到射影重构，然后通过估计绝对二次曲面，将射影重构更新到度量重构。采用真实图像测试，获得好的实验结果，说明该方法简单易用。     

Rate-Distortion Efficient Piecewise Planar 3-D Scene Representation From 2-D Images

In any practical application of the 2-D-to-3-D conversion that involves storage and transmission, representation efficiency has an undisputable importance that is not reflected in the attention the topic received. In order to address this problem, a novel algorithm, which yields efficient 3-D representations in the rate distortion sense, is proposed. The algorithm utilizes two views of a scene to build a mesh-based representation incrementally, via adding new vertices, while minimizing a distortion measure. The experimental results indicate that, in scenes that can be approximated by planes, the proposed algorithm is superior to the dense depth map and, in some practical situations, to the block motion vector-based representations in the rate-distortion sense.      

Characterization of 3-D Coronary Tree Motion From MSCT Angiography

This paper describes a method for the characterization of coronary artery motion using multislice computed tomography (MSCT) volume sequences. Coronary trees are first extracted by a spatial vessel tracking method in each volume of MSCT sequence. A point-based matching algorithm, with feature landmarks constraint, is then applied to match the 3-D extracted centerlines between two consecutive instants over a complete cardiac cycle. The transformation functions and correspondence matrices are estimated simultaneously, and allow deformable fitting of the vessels over the volume series. Either point-based or branch-based motion features can be derived. Experiments have been conducted in order to evaluate the performance of the method with a matching error analysis.      

一种双帧数字图像的双盲水印技术

本文提出一种新的安全水印嵌入技术:同时对两帧数字图像嵌入两种不同水印,对任意提取一幅图像的水印,无法恢复两个水印的任何信息.在获得双密钥情况下,方可恢复两幅图像的水印.从数学上证明了我们提出的新技术的有效性,并对算法安全性给予了分析.在变换域上给出了实现了双盲水印的算法,采用StirMark水印测试软件进行了一系列攻击性试验,其测试结果表明此技术提供了一种新的数字版权保护的方法.     

Pre-Processing of Integral Images for 3-D Displays

This paper seeks to explore a method to accurately correct geometric distortions caused during the capture of three-dimensional (3-D) integral images. Such distortions are rotational and scaling errors which, if not corrected, will cause banding and moire effects on the replayed image. The method for calculating the angle of deviation in the 3-D Integral Images is based on Hough Transform. It allows detection of the angle necessary for correction of the rotational error. Experiments have been conducted on a number of 3-D integral image samples and it has been found that the proposed method produces results with accuracy of 0.05 deg     

Reconstruction of 3-D horizons from 3-D seismic datasets

We propose a method for extracting automatically and simultaneously the quasi-horizontal surfaces in three-dimensional (3-D) seismic data. The proposed algorithm identifies connected sets of points which form surfaces in 3-D space. To improve reliability, this algorithm takes into consideration the relative positions of all horizons, and uses globally self-consistent connectivity criteria which respect the temporal order of horizon creation. The first stage of the algorithm consists of the preliminary estimation of the local direction of each horizon at each point of the 3-D space. The second stage consists of smoothing the signal along the detected layer structure to reduce noise. The last stage consists of the simultaneous building of all 3-D horizons. The output of the processing is a set of 3-D horizons represented by a series of triangulated surfaces.     

Microwave Imaging in Layered Media: 3-D Image Reconstruction From Experimental Data

A prototype microwave imaging system for imaging 3-D targets in layered media is developed to validate the capability of microwave imaging with experimental data and with 3-D nonlinear inverse scattering algorithms. In this experimental prototype, the transmitting and receiving antennas are placed in a rectangular tub containing a fluid. Two plastic slabs are placed in parallel in the fluid to form a five-layer medium. The microwave scattering data are acquired by mechanically scanning a single transmitting antenna and a single receiving antenna, thus avoiding the mutual coupling that occurs when an array is used. The collected 3-D experimental data in the fluid are processed by full 3-D nonlinear inverse scattering algorithms to unravel the complicated multiple scattering effects and produce 3-D digital images of the dielectric constant and conductivity of the imaging domain. The image reconstruction is focused on the position and dimensions of the unknown scatterers. Different dielectric and metallic objects have been imaged effectively at 1.64 GHz.      

基于红外图像的遮挡标准几何体重构方法的研究

在基于单幅红外图像自动识别并重构标准几何体的方法基础上,利用正侧两幅红外图像对带有遮挡的标准几何体的组合进行自动识别和分类,提取图像的清晰边缘后通过提取遮挡几何体未被遮挡的对称区域来提取被遮挡几何体几何特征;利用空间直角变换获得尺寸参数,最后应用三维重构模型实现多目标有遮挡的红外图像的几何体系统的三维模型重构,为复杂的红外目标的自动重构打下基础.     

一种基于多重影像实现真实感人脸三维重建的方法

基于立体视觉的基本原理,本文提出通过投影不同类型的纹理实现真实人脸几何重建的方法,第一类条纹状的纹理初步建立影像间的视差格网,为第二类精细纹理影像的匹配提供预测值,从而能够快速得到分布均匀且密集可靠的同名点.完成几何重构的基础上,提出基于外接球面实现纹理重建的方法,借助于球面坐标进行纹理影像的选取和颜色处理,减少了重建后纹理颜色的阶跃性变化,达到了匀光的目的.开发了专门的硬件系统,实验表明本文的算法简单,能够取得良好的重建效果.     

位相物体的三维非对称温度场的计算机模拟

应用计算机模拟实现了三维非对称温度场的重建，为莫尔偏折术测量三维非对称温度场提供了一种实时自动的和高精度的处理方法。     

A Hybrid Reconstruction Algorithm for 3-D Ionospheric Tomography

In this paper, a hybrid reconstruction algorithm (HRA) is presented to solve the ill-posed inverse problem associated with 3-D ionospheric stochastic tomography. In this new method, the ionospheric electron density (IED) can be inverted by using two steps. First, a truncated singular value decomposition (TSVD) method, whose value is independent on any initial estimation, is used to resolve the ill-posed problem of the tomography system. Second, taking into account the "approximation" of its solution, an iterative improvement process of the solution is then implemented by utilizing the conventional algebraic reconstruction algorithm (ART). The HRA, therefore, offers a more reasonable approach to choose an initial approximate for the ART and to improve the quality of the final reconstructed image. A simulated experiment demonstrates that the HRA method is superior to the TSVD or the ART alone for the tomographic inversion of IED. Finally, the HRA is used to perform GPS-based tomographic reconstruction of the IED at mid- and low-latitude regions.     

Direct Reconstruction of Pharmacokinetic-Rate Images of Optical Fluorophores From NIR Measurements

In this paper, we present a new method to form pharmacokinetic-rate images of optical fluorophores directly from near infra-red (NIR) boundary measurements. We first derive a mapping from spatially resolved pharmacokinetic rates to NIR boundary measurements by combining compartmental modeling with a diffusion based NIR photon propagation model. We express this mapping as a state-space equation. Next, we introduce a spatio-temporal prior model for the pharmacokinetic-rate images and combine it with the state-space equation. We address the image formation problem using the extended Kalman filtering framework. We analyze the computational complexity of the resulting algorithms and evaluate their performance in numerical simulations. An important feature of our approach is that the reconstruction of fluorescence concentrations and compartmental modeling are combined into a single step 1) to take advantage of the inherent temporal correlations in dynamic NIR measurements, and 2) to incorporate spatio-temporal a priori information on pharmacokinetic-rate images. Simulation results show that the resulting algorithms are more robust and lead to higher signal-to-noise ratio as compared to existing approaches where the reconstruction of concentrations and compartmental modeling are treated separately. Additionally, we reconstructed pharmacokinetic-rate images using in vivo data obtained from three patients with breast tumors. The reconstruction results show that the pharmacokinetic rates of indocyanine green are higher inside the tumor region as compared to the surrounding tissue.      

医学图像三维重建的研究

作为目前计算机视觉领域的一个热点问题,医学图像三维重建在诊断医学、手术规划、模拟仿真等领域都有重要的应用。首先对图像进行预处理,以去除噪声并平滑图像,然后用K均值聚类算法对图像进行分割,最后用移动立方体算法实现图像的三维重建。重建后的三维图像可以帮助医生明确诊断和制定正确的手术方案。     

用于直写组合三维周期结构的新型墨水研究

1 引言 微纳尺度材料制造的新方法将会促进材料科学、化学、物理和生物等学科的科学和工艺进步。相关材料的种类和尺寸以及结构的多样性都强调了灵活组合方法的必要性。     

冠脉树三维重建中血管段的匹配

针对冠状动脉树三维重建中血管段难以配准的问题，提出了一种新型的血管段匹配方法。该方法采用“有向二叉树”描述冠状动脉树的拓扑结构，然后根据外极线约束和拓扑约束，从冠状动脉树的根结点开始，沿血管行走方向逐级匹配分支点和端点，从而实现血管段的自动匹配。实验结果表明，该方法降低了冠状动脉树三维重建的复杂度，提高了重建的速度和精度。     

A Novel Approach to Predict Field Strength in the Shadow of a 3-D Building Scenario

A novel approach to predict field strength in the shadow of a 3-D building scenario is presented. The field strength predicted by the proposed model is compared with available measurements and earlier predicted fields based on Fresnel-Kirchhoff theory. Two different scenarios have been considered to validate our model. The proposed model gives an improvement of 7.7 dB for Scenario 1; and 5.8 dB for Scenario 2. A good agreement between the prediction and the measurement is also observed.     

Novel SPICE Compatible Partial-Element Equivalent-Circuit Model for 3-D Structures

This paper presents a novel SPICE compatible partial-element equivalent-circuit (PEEC) model for general linear medium. In this new model, the magnetized current in conductive magnet and fictitious magnetized current through the magnetic interface are considered, as well as conduction current in conductor and polarization currents in a dielectric, to model the magnetization and conduction loss effect of a conductive magnet. Corresponding equivalent circuits are derived. The magnetic field couplings between inductive cells are taken into account as current controlled current sources to avoid the time-consuming calculation of time derivatives. The new model was applied in 3-D magnetically enhanced inductor structure analysis and antenna modeling. Obtained results are compared with those obtained from commercial numerical electromagnetic simulation software and show good agreement.      

Reconstruction of 3—D Temperature Field in Holographic Interferometry

The tomography technique is commonly used for the reconstruction of holographic interferometry.However, the current reconstruction method doesnˊt consider the measurement errors which are non-avoidable in the measurement and will degrade the reconstruction quality.The factors affecting the reconstruction quality are analyzed and the distribution law of the reconstruction error with experimental errors is discussed.Finally, a method to improve the reconstruction quality-the Kalman filter method is presented.