共查询到19条相似文献,搜索用时 156 毫秒
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体素分类与Phong光照模型GPU加速体绘制 总被引:1,自引:1,他引:0
马国军 《计算机工程与设计》2010,31(7)
为了提高体绘制的速度和效果,研究了体数据的分类和计算及其在图形处理单元上加速实现的体绘制算法.分别采用点体素先分类和预积分后分类方法为体数据分配颜色和不透明度,改进了利用不透明度对颜色加权改善绘制效果,根据Phong光照模型对体数据进行渲染.通过查找表软件加速和图形处理单元硬件加速两个方面分别实现并进行比较,实验结果表明,采用图形硬件加速的方法达到实时交互的效果,体绘制性能大大提高. 相似文献
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频域体绘制中的颜色合成 总被引:1,自引:0,他引:1
和传统体绘制算法相比,频域体绘制算法具有较低的算法复杂度,能够更快地完成对三维数据场的显示.然而这种方法却不能简捷有效地表示和处理数据场的深度信息,因此其生成的图象缺少深度的遮挡效果.有鉴于此,Levoy等曾通过诸如线性深度补偿的技术来弥补这一缺憾.尽管如此,运用这种技术得到的结果和传统空域方法仍有明显的差别.本文首先着眼于对空域体绘制方法中广泛采用的离散颜色合成技术的分析,然后引出了透明度密度分布函数的概念,进而推导出连续形式颜色合成过程的解析描述.根据这个结果,只要对三维数据场的透明度分布加以适当限制,就能够通过频域体绘制方法来实现颜色合成,增加绘制的深度效果.作者最后指出,基本频域体绘制方法和Levoy的线性深度补偿方法的实质可以看成是这种颜色合成过程的近似.文中对透明度均匀分布的情况做了详细讨论,并且给出了具体算法,同时用生成的图象实例相应地进行了比较. 相似文献
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为了弥补传统体绘制静止画面时,不能明确判断场值集中部位的不足,提出了一种快速体绘制算法,针对大坝地震反应有限元计算数据场,根据每个单元法线与视线夹角最小的表面来选择剖切方向,将单元剖切成多个四边形面后进行颜色融合和叠加,大大提高了体绘制速度,实现了动态观察体绘制图,从而清楚地分析场值集中部位。 相似文献
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为了实现动态云场景的创建与绘制,文中提出一种基于体绘制的三维云模拟算法。算法用Perlin噪声干扰椭球模型,得到云场景区域内体素颜色的基本数据,然后对体素颜色进行软化模糊和添加阴影处理,建立绘制区域的云数据模型;同时通过ray casting对绘制区域进行体数据采样渲染,模拟出三维云的效果。仿真实验结果表明:该算法模拟出的云场景可让云形状颜色位置动态改变,也可让视点穿过云层,具有动态和交互效果,是一种可行的动态云场景模拟算法。 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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基于数据场特征的直接体绘制方法 总被引:2,自引:0,他引:2
论文在数据点分类的基础上,采用不同的方式计算表面采样点和内部采样点的颜色,改进了物质单一的数据场的光线投射体绘制方法。对物体模型内部的各数据点,采用一种简单的颜色映射经验模型来求解,简化了数据场内部数据点颜色的计算,减少了计算量,提高了绘制效率。 相似文献
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科学计算可视化体绘制算法能反映出体数据的内部信息,在医学,它已经从辅诊断发展成为辅助治疗的重要手段,体可视化技术是医学可视化的重要研究内容,其处理过程包括体数据的获取,模型的建立,数据的映射,绘制等操作,该文介绍了医学可视化中常使用的几种光照模型,针对基于图象空间和对象空间两种体绘制算法,介绍了它们的基本思想方法,并详细阐述了在近期的主要加速技术和提高图象质量方法的新进展,最后给出了实验数据和结论。 相似文献
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Accelerated Walkthroughs of Virtual Environments Based on Visibility Preprocessing and Simplification 总被引:1,自引:0,他引:1
This paper proposes a new preprocessing method for interactive rendering of complex polygonal virtual environments. The approach divides the space that observer can reach into many rectangular viewpoint regions. For each region, an outer rectangular volume (ORV) is established to surround it. By adaptively partitioning the boundary of the ORV together with the viewpoint region, all the rays that originate from the viewpoint region are divided into the beams whose potentially visible polygon number is less than a preset threshold. If a resultant beam is the smallest and intersects many potentially visible polygons, the beam is simplified as a fixed number of rays and the averaged color of the hit polygons is recorded. For other beams, their potentially visible sets (PVS) of polygons are stored respectively. During an interactive walkthrough, the visual information related to the current viewpoint is retrieved from the storage. The view volume clipping, visibility culling and detail simplification are efficiently supported by these stored data. The rendering time is independent of the scene complexity. 相似文献
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Kwan-Liu Ma Michael F. Cohen James S. Painter 《Computer Animation and Virtual Worlds》1991,2(4):135-140
Ray-traced volume rendering has been shown to be an effective method for visualizing 3D scalar data. However, with currently available workstation technology, interactive volume exploration using conventional volume rendering is still too slow to be attractive. This paper describes an enhanced volume rendering method which allows interactive changes of rendering parameters such as colour and opacity maps. An innovative technique is provided which allows the user to plant a ‘seed’ in the volume to rapidly modify local shading parameters. For a fixed viewing position, the user can interactively explore specific regions of interest. Furthermore, a virtual cutting technique with the exploratory seed allows the user to remove surfaces and see the internal structure of the volume. Examples demonstrate these techniques as an attractive option in many applications. 相似文献
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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
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针对交互式动态体绘制算法生成图像质量差的问题,提出一种改进算法,在减少使用插值的同时,通过增加采样点数和使用采样点间距离作为权值等方法进行图像合成。改进的算法使结果图像的质量有了明显改善,同时保持了较快的速度。 相似文献
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Timo Ropinski Jennis Meyer-Spradow Stefan Diepenbrock Jörg Mensmann Klaus Hinrichs 《Computer Graphics Forum》2008,27(2):567-576
We propose a method for rendering volumetric data sets at interactive frame rates while supporting dynamic ambient occlusion as well as an approximation to color bleeding. In contrast to ambient occlusion approaches for polygonal data, techniques for volumetric data sets have to face additional challenges, since by changing rendering parameters, such as the transfer function or the thresholding, the structure of the data set and thus the light interactions may vary drastically. Therefore, during a preprocessing step which is independent of the rendering parameters we capture light interactions for all combinations of structures extractable from a volumetric data set. In order to compute the light interactions between the different structures, we combine this preprocessed information during rendering based on the rendering parameters defined interactively by the user. Thus our method supports interactive exploration of a volumetric data set but still gives the user control over the most important rendering parameters. For instance, if the user alters the transfer function to extract different structures from a volumetric data set the light interactions between the extracted structures are captured in the rendering while still allowing interactive frame rates. Compared to known local illumination models for volume rendering our method does not introduce any substantial rendering overhead and can be integrated easily into existing volume rendering applications. In this paper we will explain our approach, discuss the implications for interactive volume rendering and present the achieved results. 相似文献