共查询到20条相似文献,搜索用时 153 毫秒
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对MITK算法平台进行研究,根据其总体框架、数据模型、算法模型的设计准则,依托该平台对医学图像序列实现基于体积元素的Marching Cubes表面绘制算法,并将绘制后的模型进行三维可视化显示。该方法构造出的等值面虽不能反映整个原始数据场的全貌及细节,但对感兴趣的等值面可以产生清晰的图像,而且可以利用现有的图像硬件实现绘制功能并进行实时交互操作。 相似文献
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众所周知,在用Lorensen和Cline的跟踪立方体(Marching Cubes)算法绘制三维数据场等值面时会产生二义性.针对这个问题,基于divide-and-conquer的思路,提出了一个从三维数据场中抽取等值面的新算法--中点递归剖分算法,实验结果表明,该算法首先将Marching Cubes算法中会产生二义性的立方体进行递归剖分,直到不存在二义性的立方体/六面体为止;然后抽取等值面只需利用非二义性立方体模式的等值面拓扑查找表即可完成;实验结果表明,该算法简单、高效、容易实现.此外,还给出了剖分算法的正确性和收敛性的构造性证明,并简明扼要地对算法的复杂度进行了分析. 相似文献
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提出了一种新颖的等值面提取算法,该算法基于Ray-Isosurface intersection方法,通过模拟三维扫描仪的工作过程来提取等值面。算法应用GPU的并行计算能力来完成主要的计算密度大的计算过程,计算结果存储为点的形式,并通过iso-splatting的技术绘制出来。算法通过控制GPU所使用的缓冲区大小和通过模拟三维扫描仪工作原理进而避免不可见部分的等值面提取,来达到一个高质量的绘制效果和高FPS的交互环境。通过该算法和传统算法在几组数据上面的绘制质量,FPS的比较证明了算法的优越性。 相似文献
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等值面提取在标量场体数据可视化和隐函数曲面显示中具有重要应用,经典算法包括移动立方体算法和移动四面体算法,其核心是在立方体或四面体体素单元中用线性的三角面片逼近原始曲面.文中以可计算的代数曲面为例,对上述2种等值面提取算法的逼近精度、时间和空间效率等方面进行了详细的对比,为各种应用中等值面提取算法的选取提供了参考依据. 相似文献
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硬件加速的等值面提取与绘制 总被引:1,自引:0,他引:1
图形硬件的发展为通用计算提供了新的平台.利用图形硬件的高密集和并行运算能力,将非规则四面体网格数据映射为纹理,在GPU中从每个四面体提取等值面片,并将其绘制到纹理而得到最终等值面.基于Cg着色器编程语言实现三维雷达作用范围表现的实验结果表明:该方法有效的减轻了CPU负担,提高了等值面提取速度,适于实时应用. 相似文献
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为了对等值面与子等值面进行提取和分组,在MC算法原理的基础上,提出了一种改进的等值面提取与子等值面分组算法。该算法首先将数据场分解为点、棱边、面与体元的拓扑结构;然后在整个数据场范围内求所有棱边与等值面的交点,并在面内连接交点形成面与等值面的交线,交线在体元内连接生成空间多边形;接着通过三角化各个体元内的空间多边形得到由顶点表与三角形表组成的等值面数据;最后根据三角形在顶点处的连接关系,采用种子算法对属于同一子等值面的三角形与顶点进行标记,属于同一子等值面的顶点与三角形将被存放在独立的顶点表与三角形表中。实验结果表明,该算法可以高效地实现等值面提取与子等值面的分组。 相似文献
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基于图像的虚拟场景实时漫游 总被引:2,自引:0,他引:2
提出一种基于图像的并行绘制算法 ,通过分割图像显示窗口并行绘制 ,实现了三维场景的高分辨率图像的实时绘制 该算法按各节点计算性能分配任务 ,实现了负载平衡 利用三维场景漫游时相邻帧之间的相关性 ,采用RLE(RunLengthEncoded)压缩方法传输图像 ,降低了传输开销 实验结果表明 ,在 4台PC组成的机群上 ,实现了5 12× 5 12大小的图像的实时绘制 相似文献
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等值面提取是研究三维数据场可视化的有效方法。针对已有的一些等值面提取算法存在的二义性问题,提出了用鞍点保证拓扑正确的快速等值面提取算法。用二线性插值和三线性插值函数来近似计算立方体表面和内部点的值,根据立方体中面鞍点和体鞍点个数的不同,将立方体剖分成不同数目的四面体。这种剖分只和原始数据的属性有关,与给定的等值无关,因此在数据不变的情况下只需要剖分一次。最后,用分层分组的方法将四面体分类到不同组中,避免在等值面提取过程中访问那些不含有等值面的四面体,从而提高了算法的速度。该算法在等值平滑变化或是随机变化时都能保持良好的特性。 相似文献
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《计算机工程与科学》2017,(10):1870-1876
针对传统面绘制重建方法 MC无法一次性提取多个阈值器官的问题,提出一种将MRI图像中靶区及其周边组织进行标签化分割的多阈值三维重建算法。该算法通过将二维图像中的多阈值器官标签化为简单的整数,降低提取等值面时的数据存储量,进而提高等值面的绘制速度。同时,定义了多阈值三维重建时体素顶点索引方式和等值面相交形态,减少了传统MC算法提取多个阈值器官时存在三角面片与顶点复用的情况,且仅需一次性扫描即可重建多个器官等值面。实验结果表明,本文算法较传统MC算法,重建器官数量越多,器官彼此结构越紧密,三角面片与顶点复用情况减少越明显,在保证重建效果的同时,绘制速度可提高30%。 相似文献
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Tomographic imaging and computer simulations are increasingly yielding massive datasets. Interactive and exploratory visualizations have rapidly become indispensable tools to study large volumetric imaging and simulation data. Our scalable isosurface visualization framework on commodity off-the-shelf clusters is an end-to-end parallel and progressive platform, from initial data access to the final display. Interactive browsing of extracted isosurfaces is made possible by using parallel isosurface extraction, and rendering in conjunction with a new specialized piece of image compositing hardware called Metabuffer. In this paper, we focus on the back end scalability by introducing a fully parallel and out-of-core isosurface extraction algorithm. It achieves scalability by using both parallel and out-of-core processing and parallel disks. It statically partitions the volume data to parallel disks with a balanced workload spectrum, and builds I/O-optimal external interval trees to minimize the number of I/O operations of loading large data from disk. We also describe an isosurface compression scheme that is efficient for progress extraction, transmission and storage of isosurfaces. 相似文献
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Weber GH Dillard SE Carr H Pascucci V Hamann B 《IEEE transactions on visualization and computer graphics》2007,13(2):330-341
Topology provides a foundation for the development of mathematically sound tools for processing and exploration of scalar fields. Existing topology-based methods can be used to identify interesting features in volumetric data sets, to find seed sets for accelerated isosurface extraction, or to treat individual connected components as distinct entities for isosurfacing or interval volume rendering. We describe a framework for direct volume rendering based on segmenting a volume into regions of equivalent contour topology and applying separate transfer functions to each region. Each region corresponds to a branch of a hierarchical contour tree decomposition, and a separate transfer function can be defined for it. The novel contributions of our work are: 1) a volume rendering framework and interface where a unique transfer function can be assigned to each subvolume corresponding to a branch of the contour tree, 2) a runtime method for adjusting data values to reflect contour tree simplifications, 3) an efficient way of mapping a spatial location into the contour tree to determine the applicable transfer function, and 4) an algorithm for hardware-accelerated direct volume rendering that visualizes the contour tree-based segmentation at interactive frame rates using graphics processing units (GPUs) that support loops and conditional branches in fragment programs 相似文献
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针对传统串行等值面提取算法在处理离散点数量多、网格点密度大的数据时生成效率差的问题,提出一种新的基于Fork/Join框架下的等值面快速生成并行算法。通过对传统串行算法中的关键步骤进行并行计算可行性分析,提出可以实施并行计算的四个单独步骤:离散点数据网格化处理、等值点计算、等值线追踪与光滑、等值面标记识别。通过将并行计算作用于等值面生成的这四个步骤中,减少了等值面计算的执行时间,加快了等值面的生成速度。实验结果表明,在数据计算量较大时,与传统串行算法相比,并行算法能在2秒内快速生成等值面,最大加速比高于5.0,提高了等值面的生成效率并取得了良好的绘制效果,满足了高实时性的业务需求。 相似文献
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三维重构方法是医学图像可视化系统、治疗计划系统的重要技术。基于图像分割的三维重构方法结合了图像分割、等值面抽取、网格简化三种技术,是不同于传统Marching Cubes算法的一种三维重构方法。它首先将医学图像分割为二值图,然后利用Marching Cubes方法进行等值面抽取,最后对得到的网格模型进行简化。实验结果表明,基于图像分割的三维重构方法加快了Marching Cubes的运算速度,改善了重构的效果,有利于实现对基于三维重构的大型几何模型的实时绘制和交互。 相似文献
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Tobias Pfaffelmoser Matthias Reitinger Rüdiger Westermann 《Computer Graphics Forum》2011,30(3):951-960
We present a novel approach for visualizing the positional and geometrical variability of isosurfaces in uncertain 3D scalar fields. Our approach extends recent work by Pöthkow and Hege [ [PH10] ] in that it accounts for correlations in the data to determine more reliable isosurface crossing probabilities. We introduce an incremental update‐scheme that allows integrating the probability computation into front‐to‐back volume ray‐casting efficiently. Our method accounts for homogeneous and anisotropic correlations, and it determines for each sampling interval along a ray the probability of crossing an isosurface for the first time. To visualize the positional and geometrical uncertainty even under viewing directions parallel to the surface normal, we propose a new color mapping scheme based on the approximate spatial deviation of possible surface points from the mean surface. The additional use of saturation enables to distinguish between areas of high and low statistical dependence. Experimental results confirm the effectiveness of our approach for the visualization of uncertainty related to position and shape of convex and concave isosurface structures. 相似文献
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Ledergerber C Guennebaud G Meyer M Bächer M Pfister H 《IEEE transactions on visualization and computer graphics》2008,14(6):1372-1379
The method of Moving Least Squares (MLS) is a popular framework for reconstructing continuous functions from scattered data due to its rich mathematical properties and well-understood theoretical foundations. This paper applies MLS to volume rendering, providing a unified mathematical framework for ray casting of scalar data stored over regular as well as irregular grids. We use the MLS reconstruction to render smooth isosurfaces and to compute accurate derivatives for high-quality shading effects. We also present a novel, adaptive preintegration scheme to improve the efficiency of the ray casting algorithm by reducing the overall number of function evaluations, and an efficient implementation of our framework exploiting modern graphics hardware. The resulting system enables high-quality volume integration and shaded isosurface rendering for regular and irregular volume data. 相似文献
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We present an efficient point-based isosurface exploration system with high quality rendering. Our system incorporates two point-based isosurface extraction and visualization methods: edge splatting and the edge kernel method. In a volume, two neighboring voxels define an edge. The intersection points between the active edges and the isosurface are used for exact isosurface representation. The point generation is incorporated in the GPU-based hardware-accelerated rendering, thus avoiding any overhead when changing the isovalue in the exploration. We call this method edge splatting. In order to generate high quality isosurface rendering regardless of the volume resolution and the view, we introduce an edge kernel method. The edge kernel upsamples the isosurface by subdividing every active cell of the volume data. Enough sample points are generated to preserve the exact shape of the isosurface defined by the trilinear interpolation of the volume data. By employing these two methods, we can achieve interactive isosurface exploration with high quality rendering. 相似文献
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文中介绍一个多分辨率并行等值面绘制系统的设计与实现。通过显示调度策略实现基于多层次细节的实时等值面绘制。着重讲述并行处理、网格简化和多分辨率显示技术。实验结果表明,该系统能在并行分布式环境下动态生成等值面的多分辨率模型,实现等值面的远程快速绘制。 相似文献