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1.
体绘制是三维数据可视化的主要方法之一。用于体绘制的数据体中包含有大量的空体素,导致光线投射算法进行没有意义的重采样计算,必然降低绘制算法效率。针对全空子数据体体绘制低效问题,本文提出基于GPU体高效绘制方法。利用八叉树数据结构组织数据,有效管理包含许多空体素的子数据体。通过绘制八叉树非全空叶子结点子数据体表面,使光线投射算法中起始和终止重采样位置更接近数据体中的可视部分,同时根据八叉树全空结点子数据体判定纹理查询结果,计算合适的跳跃步长,快速跳过八叉树中全空结点子数据体,减少无效重采样点。当数据体中空体素较多时,实现对原基于体包围盒表面绘制的GPU光线投射算法的加速。设计不透明度函数,凸显数据体中层位面,并将算法成功应用于地震数据可视化,取得很好应用效果。  相似文献   

2.
基于VTK的医学图像可视化三维重建   总被引:1,自引:0,他引:1  
医学三维数据场可视化是当前科学计算可视化应用的重点,具有重要的学术意义和应用价值.体绘制是该技术的一个主要的方法.在VTK(Visualization Toolkit)类库提供可视化与显示功能的基础上,主要讨论了光线投射算法进行体数据的绘制的特点,同时采用了包围盒技术改善了光线投射算法的绘制速度.实验结果表明,图像的质量在没有受到影响的前提下,图像的绘制速度得到了大幅度的提高,同时证明了VTK是医学三维数据场可视化的有力工具.  相似文献   

3.
目的 体绘制是3维数据可视化的主要方法之一。用于体绘制的数据体中包含有大量的空体素,导致光线投射算法进行没有意义的重采样计算,必然降低绘制算法效率。针对全空子数据体体绘制低效问题,提出基于GPU体高效绘制方法。方法 利用八叉树数据结构组织数据,有效管理包含许多空体素的子数据体。通过绘制八叉树非全空叶子节点子数据体表面,使光线投射算法中起始和终止重采样位置更接近数据体中的可视部分,同时根据八叉树全空节点子数据体判定纹理查询结果,计算合适的跳跃步长,快速跳过八叉树中全空节点子数据体。结果 当数据体中空体素较多时,确定合适的八叉树深度,有效地跳过数据体中的空体素,减少体绘制运算量,实现对原基于体包围盒表面绘制的GPU光线投射算法的加速。结论 设计不透明度函数,凸显数据体中层位面,并将算法成功应用于地震数据可视化,取得很好应用效果。  相似文献   

4.
基于CUDA海量空间数据实时体绘制研究   总被引:1,自引:0,他引:1  
针对海量空间科学数据的精细及实时三维绘制需求,提出并实现了一种基于CUDA语言的并行化光线投射体绘制加速算法,利用传统体绘制算法中光线投射法的可并行特点和GPU中高速的纹理查询的优点,通过一个实际坐标到纹理坐标的转换函数实现了对不规则采样数据的准确采样,并完成了绘制算法的CUDA并行化改造,通过CUDA语言利用GPU强大的并行计算能力实现了对海量空间数据的实时三维光线投射绘制.  相似文献   

5.
基于线性八叉树的快速直接体绘制算法   总被引:2,自引:0,他引:2  
提出了基于线性八叉树的加速体绘制算法.利用线性八叉树对物体进行空间剖分,光线投射法跨越体数据集中的空体素,以提高绘制的速度.针对光线穿越体数据时的特殊情况,改进线性八叉树邻域查找的方法,特别是不同尺寸的邻域查找方法,克服了层次八叉树邻域查找的低效率,同时提出了光线离开平面的简洁判定方法,方便光线下一个采样点的计算.实验结果表明,该算法能够有效地提高绘制的速度.  相似文献   

6.
体绘制技术是计算可视化研究和应用热点之一。在对三维数据体进行形式化定义基础上,讨论光线投射算法中数据体划分,重采样计算以及图像合成的原理和方法。利用着色器进行重采样和图像合成运算,实现体绘制的GPU加速。将GPU加速的光线投射体绘制方法应用于地震数据解释,分别实现地震数据的灰度和伪彩色样式可视化,并通过转换函数,凸显出地震数据场的层位特征,克服了地震数据剖面、切片以及三维面绘制图像的局限性。  相似文献   

7.
空间跳跃加速的GPU光线投射算法   总被引:3,自引:0,他引:3       下载免费PDF全文
光线投射算法是一种应用广泛的体绘制基本算法,能产生高质量的图像,但是时间复杂度较高。实现了一种基于图形处理器的单步光线投射算法,并在此基础上提出了一种基于空间跳跃技术的光线投射算法,以实现加速。采用八叉树组织体数据,利用空间跳跃有效地剔除体数据中对重建图像无贡献的部分,降低了硬件的负载。一个片段程序即可完成光线方向的生成、光线投射、空体素跳跃和光线终止等。实验结果表明,该算法对于内部包含大量空体素的体数据重建能起到明显的加速作用。  相似文献   

8.
为提高光线投射算法的绘制速度和图像绘制质量,提出了一种针对类球形对象的改进光线投射算法。该算法首先设置球形包围盒的方法剔除对最后绘图结果没有影响的光线投射,用快速求交的方法来提高获取采样点的速度,通过自适应采样的方法加入新的采样点来提高绘制图像的质量。实验结果表明该算法不仅比传统方法绘制出的图像质量清晰,并且提高了算法的执行速度。  相似文献   

9.
光线投射算法中重采样的设计和实现   总被引:3,自引:0,他引:3       下载免费PDF全文
体绘制技术在医学成像和科学可视化领域有着极为广泛的应用,但由于其巨大的计算开销,限制了其实时动态体绘制的应用,因此许多研究人员致力于静态体绘制加速算法的研究,为了提高体绘制速度。分析了三维规则数据场重采样的原理。光线投射算法中对3D数据场重采样的实现方法;根据具体重建对象,提出了在3D数据场重采样中采用球形包围盒的方法,给出了人体头部和眼球的三维可视化结果,实验表明:这种算法能有效地减少重采样的计算量,并使求交计算更加简单。  相似文献   

10.
体视化是地学信息三维可视化研究的前沿技术之一,体绘制算法的效率直接关系到体视化的效果。本文在研究已有光线投射体绘制改进算法的基础上,提出利用线性八叉树数据结构对光线投射体绘制算法进行改进研究,不仅实现了体数据的压缩。而且能对压缩体数据进行直接体视化。在PC机上的实验表明,该方法具有时间复杂度与数据复杂度基本无关的特点.加速效果明显。最后,文章指出了该方法的适用范围。  相似文献   

11.
Modern supercomputers enable increasingly large N‐body simulations using unstructured point data. The structures implied by these points can be reconstructed implicitly. Direct volume rendering of radial basis function (RBF) kernels in domain‐space offers flexible classification and robust feature reconstruction, but achieving performant RBF volume rendering remains a challenge for existing methods on both CPUs and accelerators. In this paper, we present a fast CPU method for direct volume rendering of particle data with RBF kernels. We propose a novel two‐pass algorithm: first sampling the RBF field using coherent bounding hierarchy traversal, then subsequently integrating samples along ray segments. Our approach performs interactively for a range of data sets from molecular dynamics and astrophysics up to 82 million particles. It does not rely on level of detail or subsampling, and offers better reconstruction quality than structured volume rendering of the same data, exhibiting comparable performance and requiring no additional preprocessing or memory footprint other than the BVH. Lastly, our technique enables multi‐field, multi‐material classification of particle data, providing better insight and analysis.  相似文献   

12.
三维真实感地形的生成一直是计算机图形学领域中的焦点课题,研究了基于层次细节的实时优化自适应网格动态地形渲染算法,采用了基于地形块包围盒的可见性投影剔除技术的实时优化策略,提出了嵌套包围球方法和屏幕空间误差法相结合的优化算法来改进误差判据,以提高地形绘制的快速性,给出了该层次细节模型在地形渲染中的实现方法。实验证明,通过对实时优化自适应网格算法的实现和优化,在保证一定的地形渲染效果的前提下,减少了开销同时提高了实时渲染速度。  相似文献   

13.
ACCELERATINGRAYTRACINGTHROUGHPOLYGONPROJECTION¥JinXiaogang;WanHuagen;PengQunsheng(StateKeyLaboratoryofCADandCGDepartmentofApp...  相似文献   

14.
While using hierarchical search structures has been proved as one of the most efficient acceleration techniques when rendering complex scenes, automatic creation of appropriate hierarchies is not solved yet. Well‐known algorithms for automatic creation of bounding volume hierarchies are not enough. Higher performance is achieved by introducing spatial uniform subdivision, although algorithms proposed up to now are not truly automatic, as they need some parameters to be adjusted. In this paper we present a full‐automatic hierarchy creation scheme that structures the scene in a hybrid way, combining bounding volumes and voxel grids in the same tree, selecting the search structure that best fits to each scene region. It uses no parameters at all. This efficient proposal relies on a new cost model that estimates the goodness of a hybrid hierarchy if used for rendering the scene. ACM CSS: I.3.7 Computer Graphics—Three‐Dimensional Graphics and Realism  相似文献   

15.
Curvature-dependent triangulation of implicit surfaces   总被引:11,自引:0,他引:11  
Implicit surfaces appear in many applications, including medical imaging, molecular modeling, computer aided design, computer graphics and finite element analysis. Despite their many advantages, implicit surfaces are difficult to render efficiently. Today's real-time graphics systems are heavily optimized for rendering triangles, so an implicit surface should be converted to a mesh of triangles before rendering. Our algorithm polyonalizes an implicit surface. The algorithm generates a mesh of close-to-equilateral triangles with sizes dependent on the local surface curvature. We assume that the implicit surface is connected and G1 is smooth (that is, the tangent plane varies continuously over the surface). The algorithm requires an evaluator for the implicit function defined at all points in space, an evaluator for the function gradient defined at points near the surface, and a bounding box around the surface. The output of the algorithm is good for applications requiring a well-behaved triangulation, such as rendering systems and finite element partial differential equation (PDE) solvers  相似文献   

16.
Spacetime ray tracing for animation   总被引:1,自引:0,他引:1  
Techniques for the efficient ray tracing of animated scenes are presented. They are based on two central concepts: spacetime ray tracing, and a hybrid adaptive space subdivision/boundary volume technique for generating efficient, nonoverlapping hierarchies of bounding volumes. In spacetime ray tracing, static objects are rendered in 4-D space-time using 4-D analogs to 3-D techniques. The bounding volume hierarchy combines elements of adaptive space subdivision and bounding volume techniques. The quality of hierarchy and its nonoverlapping character make it an improvement over previous algorithms, because both attributes reduce the number of ray/object intersections that must be computed. These savings are amplified in animation because of the much higher cost of computing ray/object intersections for motion-blurred animation. It is shown that it is possible to ray trace large animations more quickly with space-time ray tracing using this hierarchy than with straightforward frame-by-frame rendering  相似文献   

17.
This paper introduces a real‐time rendering method for single‐bounce glossy caustics created by GGX microsurfaces. Our method is based on stochastic light culling of virtual point lights (VPLs), which is an unbiased culling method that randomly determines the range of influence of light for each VPL. While the original stochastic light culling method uses a bounding sphere defined by that light range for coarse culling (e.g., tiled culling), we have further extended the method by calculating a tighter bounding ellipsoid for glossy VPLs. Such bounding ellipsoids can be calculated analytically under the classic Phong reflection model which cannot be applied to physically plausible materials used in modern computer graphics productions. In order to use stochastic light culling for such modern materials, this paper derives a simple analytical solution to generate a tighter bounding ellipsoid for VPLs on GGX microsurfaces. This paper also presents an efficient implementation for culling bounding ellipsoids in the context of tiled culling. When stochastic light culling is combined with interleaved sampling for a scene with tens of thousands of VPLs, this tiled culling is faster than conservative rasterization‐based clustered shading which is a state‐of‐the‐art culling technique that supports bounding ellipsoids. Using these techniques, VPLs are culled efficiently for completely dynamic single‐bounce glossy caustics reflected from GGX microsurfaces.  相似文献   

18.
Direct visualization of volume data   总被引:5,自引:0,他引:5  
A combination of segmentation tools and fast volume renderers that provides an interactive exploration environment for volume visualization is discussed. The tools and renderers include mechanisms that distribute volume data across multiple processors, as well as image compositing techniques and solutions to representation problems in the selection and display of subregions within bounding volumes. A volume visualization technique using the interactive control of images rendered directly from volume data coupled with a user-controlled semantic classification tool is described. The variations of parallel volume rendering being explored on the Pixel-Planes 5 system and the region-of-interest selection methods and the interactive tools used by the system are presented. The flexibility and power of combining volume rendering with region-of-interest selection techniques are demonstrated using examples of medical imaging applications  相似文献   

19.
王华  朱丽华  顾耀林 《计算机工程》2008,34(10):274-276
针对旋转曲面场景提出一种基于综合包围盒技术快速光线跟踪算法。根据二次曲线的局部单调性原理,将母线划分成多个单调区间,连接所有单调区间构造一棵二叉树,在光线跟踪阶段对每个单调区间再剖分,得到的子区间作为二叉树的叶子节点,使用综合包围壳方法为每个子区间计算合适的包围壳。实验结果表明该算法对旋转曲面场景逼近程度好,绘制的图形质量高,平均绘制速率比Kajiya传统算法提高40%。  相似文献   

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