排序方式: 共有15条查询结果,搜索用时 15 毫秒
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Tomoyuki Nishita Hiroshi Iwasaki Yoshinori Dobashi Eihachiro Nakamae 《Computer Graphics Forum》1997,16(3):C357-C364
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
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Jean-Paul Smets-Solanes 《Computer Graphics Forum》1996,15(3):289-300
This paper shows that an adequate use of vectorfields can solve most inconsistencies related to texture mapping that appear in current animation and rendering systems based on implicit objects. The method used is based on the concept of a virtual skin. A skin with its own texture mapping is spread over an implicit object and is constrained to stick to the deformation of the implicit object. A vectorfield is used to compute the relationship between the motion of the skin and the deformation of the object. Visual and implementation issues are discussed with respect to typical applications of implicit objects in computer graphics. 相似文献
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提出了一种基于二维轮廓线与超二次曲面型元球模型的造型方法,以实现简单、快速三维模型原型构造.给定一条二维轮廓线,首先使用圆或椭圆去逼近它.然后对每一个圆或椭圆设置第三个维度的参数,能够获得相应的超椭球体型元球.最后混合所有元球的场,并对所有元球的形状参数进行优化,得到一个解析的元球隐式曲面.通过调整元球的位置或形状参数构造出的曲面能够方便地实现形状的修改.模型的不同组成部分可以在不同的投影平面上勾画轮廓线相似地进行设计.该造型方法支持简单的建模操作,如布尔加、减或准扫成体生成,以生成各种复杂形状的模型.此方法能够广泛地应用在计算机图形学或计算机辅助设计领域中的概念设计阶段的原型设计工作中. 相似文献
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基于广义元球的一般约束变形 总被引:5,自引:0,他引:5
在计算机动画和形状设计中,变形是一个非常重要的工具.基于广义元球所具有的特殊势函数分布,提出了一个新的包含点、线、面和体约束的一般变形模型.用户定义一系列约束、每个约束的影响半径和偏移量,变形模型根据每个约束和其影响半径产生该约束的广义元球.广义元球确定了一个以约束点集为中心的势函数,该势函数在约束点集处为1,在影响半径处渐变为0.模型直接对整个空间进行变形,而与物体的表示无关,并且变形可由偏移量和广义元球的参数来细微调整.实验表明,该一般约束变形模型不仅有效,而且使传统方法难以做到的线、面、体约束变形成 相似文献
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基于元球隐式曲面表示,提出一个对给定3维物体表面采样数据进行自动曲面重建的方法。首先由空间采样点获取它们的球逼近表示;然后使用这些球作为元球的初始估计,构造出一张初始的元球隐式曲面;最后通过一个能量优化过程调整每个元球的形状参数,得到最终的隐式曲面。球的位置与形状的有效估计和局部支撑的元球核函数的使用极大地加速了曲面优化过程。实验结果表明该方法是有效而实用的。 相似文献
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1IntroductionComputertechnologyisnowchangingtheformandfunctionoftraditionalart.Oneinspiringaspectamongmostapplicationsinthefieldofartinvolvingcomputergraphicsisdigitalpainting.Aninteractivepaintsystemallowsanartisttoworkonasingleimage['].Whitteddescr... 相似文献
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针对目前云在各种实时应用中逼真度较差的问题,采用细胞自动机建模,把云的绘制分为预处理和实时运行2个阶段来处理;引入云的阴影关联表及变形球光照纹理数据库来提高绘制效率;同时,对云的光照散射模型中的相位函数进行了改进,使模拟的云沿视点方向呈现各向异性。实验表明:在不影响云模拟实时性的前提下,该方法有效提高了云模拟的逼真度,能够生成真实的三维光照云,满足了各种实时应用的需要。 相似文献
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