共查询到20条相似文献,搜索用时 62 毫秒
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从明暗恢复形状的手绘草图三维建模算法 总被引:2,自引:1,他引:2
提出一种通过用户手绘草图进行三维建模的算法,该算法直接利用二维笔触输入,实现简单、快捷的三维动画原型制作。首先从通过鼠标或手写板等绘制的自由曲线中析取包含手绘风格信息的结构化轮廓线,并在轮廓线所围区域中应用距离变换生成距离场;然后利用线性近似的方法从明暗恢复形状算法中获得三维曲面;接着对三维曲面进行对称、缝合和平滑变换得到基本的三维几何体;最后将基本几何体组合并进行编辑。算法强调手绘效果,提供所见即所得的交互风格,可广泛应用于三维动画和游戏的前期模型设计与制作,以及计算机辅助教学系统等领域。 相似文献
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提出了一种新的基于最小曲面距离的点云精简算法,算法在简化点云数据的同时不损失特征。点云被划分成一系列的三维子网格,根据子网格,找到最近k邻域。散乱点云的k邻域通过二次参数曲面拟合,进一步得到相关曲率。依据提出的曲面距离,对点云进行精简。选择了一些典型的点云,如冲浪、石头、陶俑、牙齿等数据对算法进行了验证。结果表明,可以直接和有效地减少点云数据,同时保持原始模型的几何形状,对点云精简研究有一定的理论和实践意义。通过实验也证明了该算法的可靠性和准确性。 相似文献
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非真实感图形绘制(Non-PhotorealisticRendering,简称NPR)能够反映三维形体的几何要素和设计风格,适合于CAD系统和卡通等艺术效果的显示绘制。利用现代可编程图形显示硬件技术,提出了一种在图像空间实现轮廓线提取和绘制的算法,并通过对Blinn-Phong光照模型的改进设计了一种适合于NPR绘制的改进光照模型。实验表明运算速度能够满足交互系统的实时性需求。 相似文献
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目的 提取马王堆帛画特征色彩,分析帛画色彩间配色关系,为文创产品设计的配色过程提供指导,在设计中更加准确地展现帛画的文化特色。方法 首先使用优化后的K-means聚类算法提取出帛画的特征色彩,生成帛画的标准色卡;然后利用图像中的色彩占比数据和色彩邻接关系,建立色彩网络模型,确定色彩主辅色搭配;最后利用CorelDRAW插件color shuffle自动生成多个配色种群,使用模糊综合评价方法验证帛画特征色彩提取的可行性与运用色彩网络模型辅助配色的可操作性。结论 使用K-means聚类方法提取出的帛画标准色卡应用于设计时具有色彩代表性,构建色彩网络模型和插件辅助配色能够提高设计师的配色效率,为文创产品的配色设计过程提供了新的思路。 相似文献
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一种改进的边界轮廓矢量化算法 总被引:4,自引:0,他引:4
左右于断层测量的反向建模中,物体断面图像序列的区域边界和实现模型重构的基础,如何从边界轮廓精确提取几何特征是实现重构的关键。本文提出一种改进的矢量化算法,该算法的基本思想是首先提取曲率极值点作为初始分段点。然后判定每两个相邻初始分段点之间轮廓线的形状,并区别直线段与曲线段分别进行拟合和矢量化。实践表明,该算法既能准确提取边界形状的特征关键点,又保证了重构后曲面的光滑规整。 相似文献
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由于手机曲面玻璃在生产过程中会产生一些外观缺陷,针对曲面玻璃上缺陷成像难、提取难等问题,提出了一种手机曲面玻璃缺陷检测方法。首先,对曲面玻璃平面部分图像进行形状匹配,并对匹配后的图像进行差分和形态学处理,提取缺陷特征;其次,对曲面玻璃曲边部分图像,使用基于连通域分析和面积阈值分割的缺陷提取算法;再次,对曲面玻璃R角部分图像,采用图像频域增强和对数变换的缺陷提取算法;最后,提取各部分缺陷后,计算得到各类缺陷的特征,通过特征进行缺陷分类,并将得到的缺陷数据与影像测量仪得到的数据进行对比实验。结果表明,该算法能准确提取手机曲面玻璃表面常见的划痕、污点、擦伤和气泡缺陷,并且缺陷尺寸精度测量能达到20μm。 相似文献
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从实测大生产物料的动态表面张力和静态表面张力数据,用表面活性剂在涂布液的扩散和在新表面吸附过程,分析涂布过程出现的余布弊病,并提出解决的办法。 相似文献
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Haoran Chen Hao Zhu Zhichao Huang Wenhui Rong Kai Wu 《Advanced materials (Deerfield Beach, Fla.)》2019,31(50)
A heterogeneous catalytic process involves many surface elementary steps that affect the overall catalytic performance in one way or another. In general, a high‐performance heterogeneous catalyst should meet the main criteria: excellent catalytic activity and high selectivity toward target products. Using surface science techniques, the two‐sidedness of the surface reaction mediations can be explored, from the perspectives of the surface and the molecule manipulations. The surface manipulation refers to a reaction that is mediated by composition and structure of the substrate as well as surface species, while the molecular manipulation relates to a reaction that is mediated by the reacting molecule via the precursor selection, environmental control, or external excitation. The best catalytic system should consist of the most efficient catalyst and the best suitable reacting molecule, in addition to its economic benefit and environmental amity. Recent research progress in surface reaction mediation is outlined, and its two‐sidedness is governed by the Arrhenius equation. This should shed new light on the connection between basic theory and surface reaction mediation strategies. To conclude, challenges and possible opportunities are elaborated for efficient surface reaction mediations. 相似文献
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Heterogenous reactions under transport control can be modelled in terms of a film of reaction products covering the reaction surface. Such a surface defines a unique direction in space which may be used to classify transport processes as transverse or longitudinal. Since crossed-gradient transport occurs, a Péclet number Pe is introduced, representing the ratio of the velocities characterizing transverse and longitudinal transport, with transverse transport being by film diffusion of some reacting species and longitudinal transport corresponding to film flow as with wetting processes. If the influence of viscosity is taken into account in terms of a Schmidt number Sc, the long-wave approximation for the evolution of thin films on reaction surfaces is shown to be equivalent to a distinguished limit Pe 0, Sc , while keeping 1/
. The long-wave approximation is derived by an application of the method of strained variables which leads to a film equation for the spatio-temporal evolution of the film thickness h which represents the crucial element for a complete solution of the thermo-hydrodynamics of the layer. Since film generation due to chemical reaction and film removal due to evaporation may compensate for certain thicknesses h, surface phases are found to occur which correspond to stationary layers of uniform thickness. The evolution of the surface layer is shown to be a generalized reaction-diffusion process, with surface waves representing dynamical transitions between surface phases. 相似文献
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基于球面三角网格逼近的等距曲面逼近算法 总被引:2,自引:0,他引:2
给出了一种基于球面三角网格逼近的等距曲面逼近新算法。利用三角网格逼近基球面,然后计算此三角网格按中心沿在曲面扫凉而成空间区域的边界作为等距曲面的逼近。该算法计算简单,方便地解决了整体误差问题,而且所得到的逼近曲面是与原曲面同次数的NURBS曲面。 相似文献