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1.
自然雪景的构造和绘制   总被引:1,自引:0,他引:1  
合成高度复杂自然场景一直是计算机图形学中的一个富有挑战性的课题。生成雪景或许更加困难,因为利用常用的造型工具,比如多边形和曲面来表达雪的形状非常不方便。该文介绍一种解决这个问题的方法,这种方法采用位移映射(displacement mapping)来构造近处由多边形构造的物体上的雪块,而体纹理映射(volumetric texture mapping)被用来处理远处的复杂物体,比如树木、绘制结果显示,这种方法能够在较少的内存和计算开销的基础上绘制出高度复杂和真实的雪景。  相似文献   

2.
基于参数空间的混合多分辨率绘制   总被引:2,自引:0,他引:2  
冀俊峰  李胜  刘学慧  吴恩华 《软件学报》2004,15(10):1515-1521
根据点和多边形在表示和绘制物体上各自不同的特点,提出了一种有效绘制细节高度复杂物体的多分辨率方法.3D表面被映射到参数平面,经规则采样成为几何图像,P-Quadtrees是基于几何图像建立的四叉树多分辨率层次结构.通过对四叉树的遍历,面向视点的表面用较大多边形面片绘制,光照细节通过法向映射完成;轮廓部分通过视点相关的LOD(level of detail)控制进行细化,使用点来绘制物体复杂精细的轮廓.通过此方法,细节复杂模型的绘制不仅可以被硬件加速,而且无论在表面还是在轮廓部分都能获得很好的视觉效果.  相似文献   

3.
如何模拟具有动态性、不规则性和随机性的自然雪景是当前虚拟现实领域研究的热点,采用位移映射构造近处多边形构造的雪块的方法,采用3ds Max创建雪景模型,导入OpenGL中加纹理映射,结合VC++2010的程序编写,以较小的系统资源消耗达到了更加实时逼真的效果,实现了整片雪花飘荡效果和虚拟雪景的真实模拟,为相关领域的动画模拟研究提供了新的思路。  相似文献   

4.
针对带有微结构表面的几何模型建模困难、模型复杂度高,导致现有阴影绘制算法效率差的问题,提出一种基于高度梯度图的阴影实时绘制方法.为实现实时渲染,首先给出一种微结构描述模型,通过将微结构高度场映射到低精度模型表面来描述复杂微结构模型;然后定义微结构高度梯度图,并据此构建可见点的局部最高点集合.在阴影绘制阶段,通过实时计算梯度空间局部最高点集合遮挡来生成细节阴影.整个阴影绘制算法在图像空间完成,较好地利用了延迟着色的思想和GPU并行计算的特点,可呈现可变形物体在动态场景中的自阴影效果.  相似文献   

5.
杨兵  李凤霞  战守义 《计算机应用》2005,25(10):2362-2364
针对基于Vega等高层平台的视景仿真系统中缺乏实时阴影绘制的缺点,提出改进方法,在场景中加入阴影绘制。研究了虚拟环境中的实时阴影生成算法和Vega提供的扩展机制,确定采用阴影映射(shadow mapping)算法,用OpenGL实现阴影绘制,并使用Vega平台提供的回调机制将阴影绘制集成到场景中,从而使生成的场景真实感更强。  相似文献   

6.
传统的图形绘制集群采用前向着色,存在光照着色功能有限、计算负载难以预测等缺陷。为此,提出基于延期着色的sort-first绘制集群架构,该系统可以实时绘制具有复杂光照效果的多边形场景,并可利用延期着色的负载可预测特性,实现绘制节点间的负载平衡。同时,提出了基于Equalizer改造现有图形绘制引擎,构造基于延期着色的sort-first绘制集群的方法。实验表明,该系统可以在静态负载平衡策略下实现高性能的实时图形绘制,具备良好的可扩展性。  相似文献   

7.
对于形状复杂且不规则的物体,点绘制能实现高的绘制效率,还能获得高质量的绘制效果。该文讨论了点绘制方法的基本原理和基本绘制管道以及点绘制方法的硬件实现,并对今后研究和发展的方向进行了展望。  相似文献   

8.
提出一种完全基于GPU的更准确的折射绘制算法.该算法不需要任何预计算,可直接绘制基于网格表示的复杂物体,能交互式地绘制动态可变形物体的多次折射和全反射现象;通过在正投影空间上进行光线与物体的求交运算来跟踪光线穿过物体的准确路径(包括折射及全反射路径),可以生成真实感很强的折射及全反射图像.最后通过在光线传播路径上使用体绘制中的散射和吸收模型来模拟半透明物体的真实感绘制.  相似文献   

9.
在计算机图形学和几何造型中,物体表面常用多边形网格模型来描述.一个复杂的场景可能会包含大量的多边形,不利于存储、传输及绘制.网格简化技术用于处理计算机图形学领域中广泛使用的多边形网格数据,主要应用领域有科学可视化、实时显示和虚拟现实等.文章给出了网格简化方法的分类,研究了基于边折叠的简化算法,对相关技术及其特点进行了介...  相似文献   

10.
高度复杂植物场景的构造和真实感绘制   总被引:15,自引:1,他引:14  
绘制高度真实感的自然场景是计算机图形学研究领域的一个富有挑战性的难题,植物对象比如草地和树木是虚拟自然场景的重要组成部分,植物类繁多,形态各异,复杂的结构使其无论在造形、存储还是在绘制上都存在相当的困难,为了解决这个难题,根据植在特点,分别采用多边形,纹元和体纹理作为工餐来构成了不同的植物,并且分别给出了不同植物场景的简单构造方法,绘制的结果证明了这些构造和绘制方法是有效可行的。  相似文献   

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在大尺度三维复杂场景中,提出了降雪和积雪快速模拟的方法,采用视景体相关和线性分组变换的方法更新雪粒子系统,改进了降雪绘制的视觉效果。针对场景尺度大、复杂度高的特点,创建视点相关遮挡图(Occlusion Map)来精细绘制近处实体的表面积雪细节,生成积雪灰度纹理图来近似模拟远处地物的整体积雪效果,实现了大场景多细节层次积雪的动态模拟。在积雪绘制过程中,近处积雪细节模拟所需的视景体参数和遮挡图通过CPU获取,将复杂的积雪位置的判定和积雪量的计算从CPU移到GPU中,利用自定义的GPU顶点和片段操作加快了积雪模拟的速度。实验结果表明,在大尺度三维复杂场景交互式操作下,提出的方法能较好地实现雪的绘制和模拟。  相似文献   

13.
The display of natural scenes such as mountains, trees, the earth as viewed from space, the sea, and waves have been attempted. Here a method to realistically display snow is proposed. In order to achieve this, two important elements have to be considered, namely the shape and shading model of snow, based on the physical phenomenon. In this paper, a method for displaying snow fallen onto objects, including curved surfaces and snow scattered by objects, such as skis, is proposed. Snow should be treated as particles with a density distribution since it consists of water particles, ice particles, and air molecules. In order to express the material property of snow, the phase functions of the particles must be taken into account, and it is well-known that the color of snow is white because of the multiple scattering of light. This paper describes a calculation method for light scattering due to snow particles taking into account both multiple scattering and sky light, and the modeling of snow.  相似文献   

14.
视觉SLAM(Simultaneous Localization And Mapping,同时定位与建图)是移动机器人领域的核心技术,传统视觉SLAM还难以适用于高动态场景并且地图中缺少语义信息。提出一种动态环境语义SLAM方法,用深度学习网络对图像进行目标检测,检测动态目标所在区域,对图像进行特征提取并剔除动态物体所在区域的特征点,利用静态的特征点进行位姿计算,对关键帧进行语义分割,在构建语义地图时滤除动态物体的地图点构建出无动态物体干扰的语义地图。在TUM数据集上进行实验,结果显示该方法在动态环境下可以提升88.3%位姿估计精度,并且可同时构建出无动态物体干扰的语义地图。  相似文献   

15.
Layered occlusion map for soft shadow generation   总被引:1,自引:0,他引:1  
This paper presents a high-quality high-performance algorithm to compute plausible soft shadows for complex dynamic scenes. Given a rectangular light source, the scene is rendered from the viewpoint placed at the center of the light source, and discretized into a layered depth map. For each scene point sampled in the depth map, the occlusion degree is computed, and stored in a layered occlusion map. When the scene is rendered from the camera’s viewpoint, the occlusion degree of a scene point is computed by filtering the layered occlusion map. The proposed algorithm produces soft shadows the quality of which is quite close to that of the ground truth reference. As it runs very fast, a scene with a million polygons can be rendered in real-time. The proposed method does not require pre-processing and is easy to implement in contemporary graphic hardware.  相似文献   

16.
When the same objects in different datasets have different positions and shapes, map alignment is necessary to minimise these geometric inconsistencies for successful map integration. In this paper, we propose a method to detect conjugate-point pairs for aligning two polygon datasets by matching the contours of corresponding polygons. This method comprises three processes, including identification of the corresponding polygon pairs, shape approximation with virtual corner-vertices and detection of conjugate-point pairs with our modified vertex-attributed-string-matching (VASM) algorithm. We applied this method to two distinct spatial datasets; a cadastral map and a topographical map of the same urban area. Then, the performance of our method was assessed visually and statistically. Both evaluations showed satisfactory results.  相似文献   

17.
The present study demonstrates the potential of hyperspectral imaging Hyperion data for the mapping of snow grain size and snow mixed objects in the Himalayan region. The spectral signatures collected using a field spectroradiometer for different types of snow grain size and vegetation-/soil-mixed snow were used for the identification/comparison of collected image spectra. Snow grain size was estimated using the spectral angle mapper (SAM) method and compared/validated with the grain sizes obtained from grain index and asymptotic radiative transfer (ART) theory methods. The overall matching area was 81% among different snow grain size classes using SAM and grain index methods. A good match was observed between the class-wise (i.e. fine, medium, and coarse) grain sizes and quantitatively obtained grain sizes using the ART theory; however, the grain diameters obtained from the ART method were small, which may be due to the difference between equivalent grain and effective optical grain size. The obtained grain size was also supported by the field snow conditions of the region. The spectra of mixed snow cover were collected from Hyperion images and compared with the spectra collected from snow mixed objects during field experiments. The vegetation-mixed and contamination/patchy (soil-mixed) snow-cover areas were identified in Hyperion scenes and the results supported using high-resolution images and snow conditions of the region. This study is of importance in the mapping of snow-cover characteristics, which can provide valuable input for climatology, hydrology, and mountain hazard applications.  相似文献   

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