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艾志玮 《工程物理研究院科技年报》2004,(1):337-337
多分辨率并行等值面绘制技术的研究与开发成为提高数据处理规模和效率的一个重要途径。本文提出基于C/S工作模式的并行等值面绘制的解决方案,即在高性能并行机上实现等值面并行提取,在远程图形工作站上实现等值面的显示。该解决方案采用并行处理、网格简化和制定显示调度策略等关键技术,实现分布式环境下远程可视化及动态多分辨率显示。并行处理加快等值面的提取,获得良好的加速性能;利用层次细节模型(LOD)技术对等值面表面进行简化,制定显示调度策略实现模型的局部选择显示和动态多分辨率显示,提高系统的交互性能。 相似文献
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对高密度差多层球壳结构件进行双能CT检测,需要研究同时基于高低能射线两套投影数据的图像重建方法。先分别重建再进行图像融合的方法,不能充分利用两种能量射线投影的互补信息,重建图像质量不高。针对高密度差多层球壳结构特征,通过设计限定投影扫描方式获取区域分布明确的高、低能射线投影正弦图,基于正弦图区域分割重组和交集数据等值化一致性处理实现双能投影数据融合,在此基础上完成图像重建。根据以上设计归纳出基于投影融合的多层球壳双能CT重建算法,仿真结果表明算法可行,且重建结果明显好于基于图像融合的方法。 相似文献
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中子偏置CT(computed tomography)扫描是一种有效的大尺寸样品层析检测方法,但投影数据截断会导致较大的CT系统转台旋转中心标定误差,严重影响成像质量。基于投影数据对称性原理,提出了一种计算旋转中心左侧和右侧投影数据和之间方差的偏置CT扫描旋转中心精确标定算法。设计了对称补数据重建算法和投影数据预处理重建算法,验证得到,对称补数据重建算法对旋转中心标定误差更为敏感,较小的误差值会导致补齐后投影数据出现拼接缝以及拼接错位问题。提出了一种中子投影数据噪声仿真方法,设计的三维仿真模体验证了所提标定算法与投影数据预处理重建算法在不同旋转中心偏置大小以及不同强度投影噪声条件下的性能优势。基于反应堆中子源开展了中子偏置CT扫描成像验证实验,获得了样品清晰的内外部结构细节,中子CT成像系统的成像视野扩大了31.4%。 相似文献
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本文基于数据重排方法, 提出了T-BPF (Tent-BPF)算法, 该算法先将锥束投影数据重排成平行投影数据, 然后使用一种推导的BPF型算法重建重排后的平行投影数据. T-BPF算法将原BPF算法反投影中变化的角度积分限变成固定的, 反投影中各层循环之间没有了相关性, 这意味着T-BPF算法较原BPF算法具有更好的可并行性. 实验结果显示: 使用GPU对2563的Shepp-Logan体模的图像重建进行并行加速, T-BPF算法在保证重建质量的前提下, 加速比达到了1036, 较原BPF算法有很大提升. T-BPF算法为截断投影数据的3D图像快速重建提供了方法.
关键词:
X射线光学
CT
图像重建
GPU 相似文献
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提出一种快速实现一维粗糙地表面下方埋藏金属目标的成像算法.用层内波传播算法结合谱加速的前后向迭代算法(PILE+FB-SA)计算一维粗糙面下方埋藏金属目标的后向散射;用得到的后向散射数据结合后向投影算法实现二维SAR(synthetic aperture radar)成像,研究窗函数的选取,讨论目标位置及尺寸大小变化的影响.用具有高斯谱的粗糙面模拟实际地表面,并采用锥形波入射以减小人为截断粗糙面引起的边缘效应.由于散射数据由快速数值算法得到,该算法不受地面和目标参数限制,可以实现任意粗糙地表面和复杂目标成像,对地下目标探测具有重要的应用价值. 相似文献
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在传统的CT系统中, 系统的硬件成本和计算量都是非常巨大的. 提出了一种利用偏移放置的面阵探测器的锥束CT系统, 在这种系统中X射线束仅仅覆盖被扫描物体的一半体积, 投影数据在探测器方向上是截断的, 探测器尺寸和投影数据量都减少为传统CT系统的一半. 在这种新型扫描方式下, 现有的CT重建算法都不能处理. 因此, 提出了一种BPF形式的直接反投影重建方法. 该方法不需要对投影数据重排, 直接反投影滤波重建出最终的图像. 因此, 该算法在数学上更简洁, 计算速度更快. 最后, 数值模拟实验和真实CT系统实验结果均验证了该系统和重建算法能够获得高质量的CT图像. 相似文献
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《光学学报》2017,(5)
传统的光学投影层析受相机感光元件动态范围及曝光时间的限制,难以对具有复杂空间结构分布的样品获取其完整且精细的三维结构信息。针对传统光学投影层析三维成像系统存在的问题,提出了在传统光学投影层析技术中引入朗伯体光源以及线性化动态范围变换的新方法。使用朗伯体光源照射样品,通过多次曝光分别对样品进行图像采集,获取相机实际响应曲线,线性化处理曲线中非线性响应区域以解决传统多次曝光动态范围变换存在的非线性失真和假象问题,然后应用图像融合技术对多次曝光获取的原始图像数据进行融合,运用反投影算法重构样品三维成像,从而获得具有复杂空间结构样品的精细三维结构信息。理论分析与成像结果表明,这种基于光学投影层析的三维结构成像新方法可以获得复杂空间结构样品更多的信息。 相似文献
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为了提高复杂背景下彩色数字图像分割的准确率,减少噪声对图像处理的干扰,尽可能的缩短运行时间,需要对复杂背景下彩色数字图像分割算法进行研究。当前图像分割算法在彩色数字图像分割的过程中,仅仅考虑了图像像素的亮度值,没有考虑其空间特征,存在计算的复杂性过大等缺陷,影响彩色数字图像处理效果。为此,提出了一种基于随机权重粒子群的复杂背景下彩色数字图像分割算法。该算法先采用多尺度均匀滤波方法,对复杂背景下彩色数据图像进行划分,其中包含噪声和不含噪声的像素点的亮度值、结构元素以及局部区域内的图像像素加权亮度密度特征。采用多段图分割获取彩色数字图像的优化分割,在平滑项中代入彩色数字图像梯度信息,对彩色数字图像分割结果中的弱边界进行剔除,从而实现准确的彩色数字图像分割。实验仿真证明,所提算法增加了彩色数字图像分割的对比度和信噪比,提高了复杂背景下彩色数字图像分割的准确性。 相似文献
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目前,GPU渲染技术仍然存在不足之处,在分配渲染任务时,没有充分发挥各个处理器的优势,浪费了性能较好的处理器,影响了渲染速度的提高。针对以上问题,根据武进区邹区现代农业产业园人口疏散地域接收安置动画的项目,在原有GPU渲染架构的基础上提出了一种基于sort-last架构的带反馈的动态负载均衡算法。在分配渲染任务之前,对所有处理器进行性能统计,将时长较长的场景分配给性能较好的处理器,时长短的分配给剩余的处理器,待有处理器完成渲染任务时,将剩余场景时间较长的,分配给第一轮任务先完成的处理器,以此类推。实验结果表明,该方法对解决上述问题具有较好的效果,解决了目前集群渲染存在的不足之处和负载不平衡的问题,最终实现了加速渲染。 相似文献
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In this report, a new rendering method of a moving sound with the Doppler effect is proposed. In the conventional rendering method of moving sound, Head Related Impulse Responses (HRIRs) are simply changed according to a sound position. However, the Doppler effect cannot be added to a sound in this method. The pitch of a sound object must be controlled using some other rendering method when a sound object moves at high speed. In our method, each HRIR is divided into two components, such as an initial delay and a main wave form. Two initial delays of both right and left ears are recalculated, respectively, based on relative speeds and a propagation path. These new initial delays are used in rendering. Therefore, the Doppler effect is added to a sound automatically only when a sound position is set in this algorithm. Details related to this algorithm are discussed in this report. 相似文献
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D. Murawski G. Lindig U. Zelck K. Repke 《Isotopes in environmental and health studies》2013,49(7):282-286
With tritium gas acting upon the solutions of cardio-active unsaturated steroid lactones in the presence of catalysts, there results a mixture of labelled parent compounds and labelled dihydroderivates. The influence of various catalysts upon transformation speed and radiochemical yield ratio of exchange and addition products has been investigated. A method rendering possible preparative separation of the obtained cardenolides and cardanolides labelled with tritium is described. 相似文献
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J.L.Dillenseger 《中国科学G辑(英文版)》2005,48(1):1-13
This paper presents a new 3D edge operator based on Legendre orthogonal moments. This operator can be used to extract the edge of 3D object in any window size, with more accurate surface orientation and more precise surface location. It also has full geometry meaning. Process of calculation is considered in the moment based method. We can greatly speed up the computation by calculating out the masks in advance. We integrate this operator into our rendering of medical image data based on ray casting algorithm. Experimental results show that it is an effective 3D edge operator that is more accurate in position and orientation. 相似文献
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R. De G. Ananthakrishna 《The European Physical Journal B - Condensed Matter and Complex Systems》2008,61(4):475-483
We investigate the dynamics of peeling of an adhesive tape subjected to a constant pull speed. Due to the constraint between
the pull force, peel angle and the peel force, the equations of motion derived earlier fall into the category of differential-algebraic
equations (DAE) requiring an appropriate algorithm for its numerical solution.
By including the kinetic energy arising from the stretched part of the tape in the Lagrangian, we derive equations of motion
that support stick-slip jumps as a natural consequence of the inherent dynamics itself, thus circumventing the need to use
any special algorithm. In the low mass limit, these equations reproduce solutions obtained using a differential-algebraic
algorithm introduced for the earlier singular equations. We find that mass has a strong influence on the dynamics of the model
rendering periodic solutions to chaotic and vice versa. Apart from the rich dynamics, the model reproduces several qualitative
features of the different waveforms of the peel force function as also the decreasing nature of force drop magnitudes. 相似文献
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A polarization stabilizer up to 12.6 krad/s with an additional function of stable state of polarization transformation 下载免费PDF全文
This paper reports on an experiment about a novel method
of polarization stabilization. The polarization stabilizer proposed
here has an additional function of polarization transformation from
any state of polarization into any others. The particle swarm
optimization is introduced as a control algorithm in the process of
either searching or endless tracking. The tracking speed of the
stabilizer is obtained up to 12.6~krad/s by using hardware we
have in the laboratory, which means that we can achieve a higher speed
practical polarization stabilizer if we have faster hardware. 相似文献
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Abstract
This paper presents a new technique for real-time isosurface visualization of three-dimensional smooth fields. This technique enables direct isosurface rendering of smoothly defined fields without generating intermediate polygon models as used in the marching-cube algorithm, a standard technique for isosurface extraction. We developed a parallel algorithm that is suitable for effective computation on graphics hardware by converting any field to a set of polynomials, enabling the detection of intersections between rays and isosurfaces at arbitrary isovalue with small computational cost. In addition, the isovalue to be rendered can be changed in real time, because the algorithm is not restricted to a specific isovalue. The technique can also be applied to the problem of the direct rendering of implicit surfaces that are defined as isosurfaces of smoothly defined fields. 相似文献20.
A New Fourier Iterative Algorithm for the Design of Phase-only Diffractive Optical Element Used in Laser Beam Shaping 总被引:3,自引:0,他引:3
ANewFourierIterativeAlgorithmfortheDesignofPhase-onlyDiffractiveOpticalElementUsedinLaserBeamShapingSANGTao;LIAOJianghong;LUZ... 相似文献