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In this paper, a novel reconstruction technique based on level set method and algebraic reconstruction technique is proposed for multiphase flow computed tomography (CT) system. The curvature-driven noise reduction method is inserted into the conventional iteration procedure of algebraic reconstruction technique to improve the image quality and convergence speed with limited projection data. By evolving the image as a set of iso-intensity contours after each updation, the sufficient number of iterations for acceptable results is reduced by 80%-90%, while the image quality is enhanced obviously. Quantitative evaluation of image quality is given by using both relative image error and correlation coefficient. The resultant images can be utilized to detect flow regimes for monitoring industrial multiphase flow. Laboratory results demonstrate the feasibility of the proposed method. Phantoms of four typical flow regimes can be reconstructed from few-view projection data efficiently, and the corresponding image errors and correlation coefficients are acceptable for the cases tested in this paper. 相似文献
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INTRODUCTION Electrical capacitance tomography (ECT) is based on measuring the variation in capacitance be- tween pairs of electrodes surrounding a subject, and reconstructing the distribution of dielectric properties in the sensing area using the measured data. For im- age reconstruction with ECT, the linear back-pro- jection (LBP) algorithm is the most popular (Xie et al., 1992). However, it can only produce qualitative im- ages. In many cases, it is necessary to provide quantitativ… 相似文献
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GUO Qiang YANG Xin 《浙江大学学报(A卷英文版)》2006,7(6):960-968
INTRODUCTION 3D echocardiography has been widely used in diagnostic cardiology because it can visualize the complex structure of heart more accurately than pre-vious used 2D diagnosis method. Currently, there are two major image acquisition methods of 3D echo-cardiography, i.e., random data acquisition and se-quential data acquisition (Roelandt, 2000). The for-mer uses a spatial locator to measure the position and orientation of the ultrasound probe, allowing unre-stricted (free-hand) s… 相似文献
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基于并行粒子群算法的Otsu双阈值医学图像分割 总被引：1，自引：0，他引：1
医学图像分割一直是医学影像分析领域的研究热点。由于粒子群优化(PSO)容易陷入局部极小,因此该算法用于搜索某些函数极值时精确度较低且稳定性较差。针对该问题,结合Otsu分割技术,提出了一种基于并行粒子群优化算法的Otsu双阈值医学图像分割算法。在该算法中,将粒子群体分成若干个子群体,进化在多个不同的子群中并行进行,避免单种群进化过程中出现的过早收敛现象,提高整个算法的收敛速度。实验结果表明,提出的分割算法与传统粒子群算法相比,不仅能够对图像进行准确的分割,而且具有更强的精确性和稳定性,其收敛速度明显优于基于单种群的粒子群算法的Otsu双阈值医学图像分割。 相似文献
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WU Xue-dong SONG Zhi-huan 《浙江大学学报(A卷英文版)》2007,8(10):1604-1613
Determination of relative three-dimensional (3D) position, orientation, and relative motion between two reference frames is an important problem in robotic guidance, manipulation, and assembly as well as in other fields such as photogrammetry. A solution to pose and motion estimation problem that uses two-dimensional (2D) intensity images from a single camera is de- sirable for real-time applications. The difficulty in performing this measurement is that the process of projecting 3D object features to 2D images is a nonlinear transformation. In this paper, the 3D transformation is modeled as a nonlinear stochastic system with the state estimation providing six degrees-of-freedom motion and position values, using line features in image plane as measuring inputs and dual quaternion to represent both rotation and translation in a unified notation. A filtering method called the Gaussian particle filter (GPF) based on the particle filtering concept is presented for 3D pose and motion estimation of a moving target from monocular image sequences. The method has been implemented with simulated data, and simulation results are provided along with comparisons to the extended Kalman filter (EKF) and the unscented Kalman filter (UKF) to show the relative advantages of the GPF. Simulation results showed that GPF is a superior alternative to EKF and UKF. 相似文献
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多帧图像超分辨率重建技术就是将一些变形、模糊、降采样的低分辨率图像进行融合,估计出一幅高分辨率图像,其步骤主要分为运动估计、插值处理、图像重建.本文采用Vandewalle配准方法将处理过的低分辨率图像序列映射到一幅高分辨率网格上,然后进行插值,最后结合小波变换和迭代方法进行图像重建,并采用小波阈值去噪方法进行去噪处理.实验结果表明：本算法能较好地提高图像的峰值信噪比,是图像重建的一种有效方法. 相似文献
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基于数字移相全息的图像重构 总被引：3，自引：0，他引：3
1IntroductionDifferent methods of holographic interferometry re-lated techniques have been used effectively for defectvisualisation in artwork diagnosis[1].Physical recon-struction of recorded wave fields though is of li mitedapplicability for on-field or… 相似文献
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A novel technique of three-dimensional reconstruction segmentation and analysis for sliced images of biological tissues 总被引：5，自引：0，他引：5
INTRODUCTION The past decades witnessed unprecedented ad-vances in the imaging science fields(Yelbuz et al.,2002;Campagnola et al.,2002;Sharpe et al.,2002).The technique of3D image reconstruction andanalysis plays a significant role in the basic researchof life science,which developed from2D imageprocessing but provides more information than2Dimage,and has rapidly expanded to molecular andcellular field(Guo et al.,1995;Trehan et al.,2003).Despite the rapid development of the new field,… 相似文献
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Volume rendering of 3D data sets composed of sequential 2D medical images has become an important branch in image processing and computer graphics.To help physicians fully understand deep-seated human organs and focuses(e.g.a tumour)as 3D structures.in this paper,we present a modified volume rendering algorithm to render volumetric data,Using this method.the projection images of structures of interest from different viewing directions can be obtained satisfactorily.By rotating the light source and the observer eyepoint,this method avoids rotates the whole volumetric data in main memory and thus reduces computational complexity and rendering time.Experiments on CT images suggest that the proposed method is useful and efficient for rendering 3D data sets. 相似文献
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Sample based 3D face reconstruction from a single frontal image by adaptive locally linear embedding 总被引：1，自引：0，他引：1
ZHANG Jian ZHUANG Yue-ting 《浙江大学学报(A卷英文版)》2007,8(4):550-558
In this paper, we propose a highly automatic approach for 3D photorealistic face reconstruction from a single frontal image. The key point of our work is the implementation of adaptive manifold learning approach. Beforehand, an active appearance model (AAM) is trained for automatic feature extraction and adaptive locally linear embedding (ALLE) algorithm is utilized to reduce the dimensionality of the 3D database. Then, given an input frontal face image, the corresponding weights between 3D samples and the image are synthesized adaptively according to the AAM selected facial features. Finally, geometry reconstruction is achieved by linear weighted combination of adaptively selected samples. Radial basis function (RBF) is adopted to map facial texture from the frontal image to the reconstructed face geometry. The texture of invisible regions between the face and the ears is interpolated by sampling from the frontal image. This approach has several advantages: (1) Only a single frontal face image is needed for highly automatic face reconstruction; (2) Compared with former works, our reconstruction approach provides higher accuracy; (3) Constraint based RBF texture mapping provides natural appearance for reconstructed face. 相似文献
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主要对平面型场景图像的三维度量重建方法进行详细的研究阐释，提出了层次化的平面型场景图像三维度量重建方法。该方法不必对摄像机定标，首先根据平行线来计算图像平面的消失线得到仿射重建，然后在仿射平面上利用直线之间的已知相对长度、已知角度和相等未知角来计算圆点得到度量重建。 相似文献
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利用VTK可视化工具包在Visual Studio2008平台上实现了医学序列图像三维的可视化．在对三维数据的预处理和优化基础上,在MFC实现的可交互界面上,用Marching Cubes（立方体移动）算法和Ray—casting（光线投射）算法对DICOM等格式的切片进行三维重建． 相似文献
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人体切片数据的三维重建系统设计 总被引：2，自引：0，他引：2
阐述了利用人体切片数据，从二维图像中提取三维信息，并采用OpenGL开发工具进行三维重建的方法。根据不同点云绘制方法与计算消耗时间的关系，重点提出如何结合点云绘制与网格绘制，有效、快速的实现了人体切片数据的三维重建。 相似文献
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火焰算法是计算机图形学中的一个热点,目前已经出现了多种不同的实现算法.本文采用Java语言实现了基于粒子系统的算法和Blur算法,并对两种算法的空间复杂度、时间复杂度和视觉效果进行了分析与比较. 相似文献
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Medically,electrical impedance tomography(EIT)is a relatively inexpensive,safe,non-invasive and portable technique compared with computerized tomography(CT)and magnetic resonance imaging(MRI).In this paper,EIT_TJU_Ⅱ system is developed including both the data collection system and image reconstruction algorithm.The testing approach of the system performance,including spatial resolution and sensitivity,is described through brine tank experiments.The images of the thorax physical model verify that the system can reconstruct the interior resistivity distribution.Finally,the lung ventilation functional monitoring in vivo is realized by EIT,and the visualized images indicate that the configuration and performance of EIT_TJU_Ⅱ system are feasible and EIT is a promising technique in clinical monitoring application. 相似文献
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SLAM is one of the most important components in robot navigation. A SLAM algorithm based on image sequences captured by a single digital camera is proposed in this paper. By this algorithm, SIFT feature points are selected and matched between image pairs sequentially. After three images have been captured, the environment＇s 3D map and the camera＇s positions are initialized based on matched feature points and intrinsic parameters of the camera. A robust method is applied to estimate the position and orientation of the camera in the forthcoming images. Finally, a robust adaptive bundle adjustment algorithm is adopted to optimize the environment＇s 3D map and the camera＇s positions simultaneously. Results of quantitative and qualitative experiments show that our algorithm can reconstruct the environment and localize the camera accurately and efficiently. 相似文献
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黎杨梅 《襄樊职业技术学院学报》2012,11(2):39-40
CT图像或者MRI图像都是单方向的二维图像序列。有时基于精确确定病灶位置的需要,医生需要从不同的方向观察不同位置的二维图像,即医学图像体数据切片技术。本文介绍了Z轴切片法和平面切片法两种医学图像体数据切片技术,并分别由这两种技术完成了体数据冠矢状切面显示模块和体数据任意切面显示模块。 相似文献
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Adaptive support-weight (ASW) stereo matching algorithm is widely used in the field of three-dimensional (3D) reconstruction owing to its relatively high matching accuracy. However, since all the weight coefficients need to be calculated in the whole disparity range for each pixel, the algorithm is extremely time-consuming. To solve this problem, a fast ASW algorithm is proposed using twice aggregation. First, a novel weight coefficient which adapts cosine function to satisfy the weight distribution discipline is proposed to accomplish the first cost aggregation. Then, the disparity range is divided into several sub-ranges and local optimal disparities are selected from each of them. For each pixel, only the ASW at the location of local optimal disparities is calculated, and thus, the complexity of the algorithm is greatly reduced. Experimental results show that the proposed algorithm can reduce the amount of calculation by 70% and improve the matching accuracy by 6% for the 15 images on Middlebury Website on average. 相似文献
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This paper presents a pure vision based technique for 3D reconstruction of planet terrain. The reconstruction accuracy depends ultimately on an optimization technique known as ＇bundle adjustment＇. In vision techniques, the translation is only known up to a scale factor, and a single scale factor is assumed for the whole sequence of images if only one camera is used. If an extra camera is available, stereo vision based reconstruction can be obtained by binocular views. If the baseline of the stereo setup is known, the scale factor problem is solved. We found that direct application of classical bundle adjustment on the constraints inherent between the binocular views has not been tested. Our method incorporated this constraint into the conventional bundle adjustment method. This special binocular bundle adjustment has been performed on image sequences similar to planet terrain circumstances. Experimental results show that our special method enhances not only the localization accuracy, but also the terrain mapping quality. 相似文献