共查询到20条相似文献,搜索用时 78 毫秒
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体绘制方法是当前研究的一个热点问题,它的应用遍及医学、地质学、物理学、和科学计算等诸多领域。但目前它仍处于发展阶段,有许多问题都有待于进一步的研究。该文对体绘制方法中的若干算法进行了研究与比较,实现的算法是基于开发平台windows SDK,用C语言和原始的API编写Windows程序,以提供最佳的性能、最强大的功能和最大的灵活性。 相似文献
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体绘制方法是当前研究的一个热点问题,它的应用遍及医学、地质学、物理学、和科学计算等诸多领域。但目前它仍处于发展阶段,有许多问题都有待于进一步的研究。该文对体绘制方法中的若干算法进行了研究与比较,实现的算法是基于开发平台windows SDK,用C语言和原始的API编写Windows程序,以提供最佳的性能、最强大的功能和最大的灵活性。 相似文献
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高效光线投射体绘制算法研究 总被引:2,自引:0,他引:2
重点研究了体绘制算法具体实现过程。为提高图像质量,采用相邻梯度、高阶内插、简单过采样等方法,并提出数据分块、代码优化、跳采样等具体途径。上述方法的组合使用,取得了满意的效果。 相似文献
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作为体绘制中的一个经典绘制算法,光线投射算法理论简单同时能产生高质量的图像,被广泛应用于医学图像可视化领域。但在绘制过程中有大量的投射光线和体素的重采样,导致绘制速度较为缓慢。为提高绘制的速度,文中提出一种高效的光线投射体绘制算法,通过引入碰撞检测技术减少投射光线的数目,避免冗余光线的采样计算,同时采用光线跳跃方法在碰撞检测包围盒内跳过对空体素的重采样,加快了光线合成的过程。实验结果表明,改进后的算法不仅能保证所需要的图像质量,还能大幅度地减少采样计算的时间,高效地提高绘制速度。 相似文献
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针对特征信息抽取,在传统光线投影体绘制过程中引入深度参数,提出了一种基于深度的体绘制算法.通过深度及角度交互,指导特征信息及其上下文信息的绘制.该算法将采样点深度转换成相应深度强度值,按给定方法与已知透明度值合成,得到新透明度值.在此基础上再进行颜色值合成,生成图像.给出了结果,分析了采用算法前后的效果. 相似文献
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彩色三维体数据场的直接体绘制方法 总被引:2,自引:0,他引:2
提出基于光线投射和三维纹理映射的彩色体数据成像算法,研究如何从每个体素的R,G,B三元组映射成不透明度值,即不透明度转换函数。首先把原始的RGB色彩空间转换成LUV色彩空间;然后以亮度分量的中心差分来近似估计法向量,并应用Phong光照模型进行着色,根据亮度分量及其梯度等信息计算不透明度值;最后合成、累积颜色。对美国数字人男子照相彩色体数据分别采用两种算法进行实验。结果表明:基于光线投射的彩色体数据算法成像质量较高,可以表现体表毛细血管等细微结构,但速度较慢;基于三维纹理映射的彩色体数据成像算法速度较快,但成像质量适中。 相似文献
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Interactive ray tracing for volume visualization 总被引:6,自引:0,他引:6
Parker S. Parker M. Livnat Y. Sloan P.-P. Hansen C. Shirley P. 《IEEE transactions on visualization and computer graphics》1999,5(3):238-250
Presents a brute-force ray-tracing system for interactive volume visualization. The system runs on a conventional (distributed) shared-memory multiprocessor machine. For each pixel, we trace a ray through a volume to compute the color for that pixel. Although this method has a high intrinsic computational cost, its simplicity and scalability make it ideal for large data sets on current high-end parallel systems. To gain efficiency, several optimizations are used, including a volume bricking scheme and a shallow data hierarchy. These optimizations are used in three separate visualization algorithms: isosurfacing of rectilinear data, isosurfacing of unstructured data, and maximum-intensity projection on rectilinear data. The system runs interactively (i.e. at several frames per second) on an SGI Reality Monster. The graphics capabilities of the Reality Monster are used only for display of the final color image 相似文献
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B. Kh. Barladyan A. G. Voloboi K. A. Vostryakov V. A. Galaktionov L. Z. Shapiro 《Programming and Computer Software》2008,34(5):294-303
As the power of modern microprocessors increases, the coherent ray tracing becomes increasingly popular in computer graphics because the use of SIMD instructions considerably speeds up this operation. However, after speeding up ray tracing, it turns out that other algorithms for physically accurate rendering, such as the calculation of illumination or application of texture, etc., become a bottleneck in improving the performance. In this paper, a coherent physically accurate rendering algorithm is proposed that makes use of SIMD instructions of modern processors at each stage of the image generation. Coherent algorithms for the calculation of illumination and materials, for antialiasing, and for tone mapping are presented. The comparison of the execution time of coherent and incoherent algorithms using benchmark scenes showed that the former are considerably faster. 相似文献
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This paper presents a real-time ray casting rendering algorithm for “volume clipping plane“ as an extension of the conventional ray casting technique.For each viewing direction a(moderate) pre-processing step is performed:the ray traverses the entire volume data (no early ray termination).Its intensity and opacity contributions are divided into several segments which are then sorted and stored by depth.At each sampling position along a segment,accumulated trans-parency and color are stored at a moderate memory overhead.For visualizing real-time volumeclipping,only relevant segment contributions (maximum two) at the location of the clipping plane are considered,thus reducing the calculation to meet real-time requirements.Compared with theprevious work that involves time-consuming re-clipping,re-traversing and re-shading,the proposed method achieves quality identical to ray casting at real-time speed.The performance is indepen-dent of the volume resolution and/or the number of clipping planes along a given viewing direction.Therefore it is suitable for real-time “internal volume inspections“,involving one or several cutting planes,typically applied e.g.,in medical visualization and material testing applications. 相似文献
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设计和实现了GPU上基于流的光线跟踪算法,采用一种基于线索二叉树的KD-Tree结构组织场景,避免了传统KD-Tree结构在遍历场景时在堆栈上的开销。算法在组织复杂场景上,优于利用传统KD-Tree和均匀剖分结构加速场景遍历的方法,在普通PC上实现了光线跟踪的快速渲染。 相似文献
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目的 模拟绘制焦散效果是真实感图形绘制的重要组成部分。利用可编程GPU硬件,基于图像的光子映射方法绘制速度快,但由于使用了近似采样和计算,会产生失真。为了克服这一现象,针对理想的镜面反射、折射体,提出一种快速绘制焦散效果的方法(VOBPBT)。方法 该方法首次定义了光子路径映射图的概念,并提出通过基于虚顶点光子映射的光子束跟踪来准确构建光子路径映射图的方法;此外,方法也创新性地提出利用光子路径映射图来查找焦散三角形,创建焦散映射图的方法。结果 实验结果表明,本文绘制结果真实,可以处理多次递归反射、折射,能够绘制连贯的高频焦散效果,同时可以达到交互的绘制性能。结论 本文VOBPBT方法在可交互计算机仿真、计算机游戏、虚拟漫游等应用领域具有一定的实用价值。 相似文献
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We propose a method to accelerate direct volume rendering using programmable graphics hardware (GPU). In the method, texture slices are grouped together to form a texture slab. Rendering non-empty slabs from front to back viewing order generates the resultant image. Considering each pixel of the image as a ray, slab silhouette maps (SSMs) are used to skip empty spaces along the ray direction per pixel basis. Additionally, SSMs contain terminated ray information. The method relies on hardware z-occlusion culling and hardware occlusion queries to accelerate ray traversals. The advantage of this method is that SSMs are created on the fly by the GPU without any pre-processing. The cost of generating the acceleration structure is very small with respect to the total rendering time. 相似文献
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A hybrid ray tracer for rendering polygon and volume data 总被引:7,自引:0,他引:7
Volume rendering, a technique for visualizing sampled functions of three spatial dimensions by computing 2-D projections of a colored semitransparent volume, is extended to handle polygonally defined objects. A hybrid ray-tracing algorithm, whereby rays are simultaneously cast through a set of polygons and a volume data array, is used. Samples of each are drawn at equally spaced intervals along the rays, and the resulting colors and opacities are composited together in depth-sorted order. To avoid aliasing of polygonal edges at modest computational expense, a form of selective supersampling is used. To avoid errors in visibility at polygon-volume intersections, special treatment is given to volume samples lying immediately in front of and behind polygons. The cost, image quality, and versatility of the algorithm are evaluated using data from 3-D medical imaging applications 相似文献