Extending FABRIK with model constraints

Forward and Backward Reaching Inverse Kinematics (FABRIK) is a recent iterative inverse kinematics solver that became very popular because of its simplicity, convergence speed and control performance, especially in models with multiple end effectors. In this paper, we extend and/or adjust FABRIK to be used in problems with leaf joints and closed‐loop chains and to control a fixed inter‐joint distance in a kinetic chain with unsteady data. In addition, we provide optimisation solutions when the target is unreachable and a proof of convergence when a solution is available. We also present various techniques for constraining anthropometric and robotic joint models using FABRIK and provide clarifications and solutions to many questions raised since the first publication of FABRIK. Finally, a human‐like model that has been structured hierarchically and sequentially using FABRIK is presented, utilising most of the suggested joint models; it can efficiently trace targets in real time, without oscillations or discontinuities, verifying the effectiveness of FABRIK. Copyright © 2015 John Wiley & Sons, Ltd.     

Vortex particle smoke simulation with an octree data structure

We propose an octree‐based presentation of vortex particles to simulate smoke and gaseous phenomena in a physical way. Vortex particle method prevails over grid‐based method in terms of less numerical dissipation and more detail features, but it suffers from heavy computational overhead due to per‐particle Biot–Savart integration over the entire simulation space. To alleviate this problem, we employ an octree background grid to separate the vortex particles into individual groups. Particles in groups are aggregated as a single super vortex particle to reduce computational cost. The proposed method produces comparable visual result as previous methods with much less computational overhead. Copyright © 2014 John Wiley & Sons, Ltd.     

基于用户体验的文创产品动漫化设计研究

目的提出一种基于用户体验的文创产品动漫化的设计方法,使文创产品设计能够满足用户体验的需求。方法在用户体验研究的基础上,通过分析当前文创产品设计方法的研究现状,以及动漫化表现手法对文创产品设计的影响和意义,归纳总结了用户体验三层次与文创产品动漫化设计表现的映射关系,建立了表达文创产品文化特色的设计方法流程。将鼎文化中鼎的造型进行动漫化设计,以其中具有典型性的文化元素为代表,并对这些文化元素的特征进行动漫化设计表达,得到了满足用户体验的文创产品动漫化设计方案。结论该设计方法解析了用户体验,并将其映射为设计要求,结合动漫化设计表现,使用户在与文创产品接触的过程中获得深层次的用户体验,为文创产品的设计研究提供一种崭新的设计思路。     

基于可编程GPU的骨骼动画

骨骼动画与以前的动画方法相比,具有占用空间小等优点。但是其代价是计算量的增加,从而导致绘制效率的降低。另一方面,近年来可编程GPU技术在三维图形处理领域已得到广泛研究。因此,提出了一种基于GPU实现骨骼动画的方法。该方法借助GPU强大的计算能力,分担了骨骼动画中的顶点更新的计算任务,从而大大提升了骨骼动画的绘制效率。     

Notes on Designing Surficial Elegance

Mastery of technique is as essential as design ability to the production of elegant works. Elegant features can only be realised through an understanding of the systemic logics of the digital environment and a full working knowledge of generative techniques. Benjamin H Bratton of The Culture Industry and Hernan Diaz Alonso of Xefirotarch describe Xefirotarch's wholly visceral, but exacting, approach to the design process. Copyright © 2007 John Wiley & Sons, Ltd.     

动漫图形在包装设计中的创意表现

提出在包装设计中应用动漫图形,应结合商品诉求,运用提炼概括、夸张、拟人、同构、文图结合、图形组合等设计手法进行创意表现,以传达商品信息,吸引消费者。     

An articulated limb motion planner for optimized movement

Task level animation of articulated figures, such as the human body, requires the ability to generate collision-free goal-directed motion of individual limbs in the presence of obstacles. This paper describes a new articulated limb motion planner for goal-directed point-to-point reaching motions. The produced motion avoids obstacles while optimizing an objective function. This two-phase algorithm uses heuristic guided Monte Carlo techniques to create a consistent underlying paradigm. The first phase consists of an existing potential field based random path planner which generates a population of candidate paths. This initial population is fed into the second phase, a genetic algorithm, which iteratively refines the population as it optimizes with respect to the objective function. The refinement process works on the principle of path coherency, the idea that a family of closely related collision-free paths lies in the vicinity of a given collision-free path. This paper focuses on seven different optimization functions. Optimized trajectories produced by the new motion planner are compared to those generated solely by the random path planner. The presented algorithm is flexible in that a wide range of objective functions can be optimized. Applications of the algorithm include task level animation, ergonomics and robotics.     

支持多模即时控制的角色动画库

该文主要介绍了一个支持多模即时控制的角色动画库,包括其整体架构、脚本格式和动画引擎。提出了一种通过以XML作为主要格式的角色定义,将角色、骨架和动作定义相分离以提高动画库的复用性的方法。采用动作有限状态机使得系统能够通过一系列的动画指令来控制动画角色的行为,简化了对动画角色的控制。同时系统通过支持多模输入并在虚拟化身上做出即时反应,增强了虚拟现实应用中的沉浸感、临场参与感和交互性。     

基于参数自适应延时反馈的混沌系统控制及应用

针对延迟反馈法参数较难确定的问题,给出了一种自适应调节反馈系数方法来控制非线性Lorenz混沌系统的方案.数值仿真结果表明,选择适当的延迟时间和反馈系数能够控制系统的不稳定周期轨道、消除混沌,并能使系统从失稳状态进入稳定状态.由于不需要外加参考信号,可以在混沌态的任意时刻施加控制,所以该方法简单易行.同时将以上控制效果应用于动画的控制中,对指定动画角色行为进行控制,使其可以运动到混沌的轨道上或者某一个特殊的轨迹上.     

快速真实地生成树的自然摇曳

快速真实地模拟树在风中的摇曳一直是图形学中的一个挑战性问题．已有的方法,或者计算速度太慢,或者所处理的模型局限在几千个面片之内,难以用较强的真实感进行动画模拟．针对复杂树在风中的自然摇曳,该文提出一种新的方法．一方面,它基于统计数据采用高斯分布来近似逼近实际风力,既可以基于物理性态很好地反映风力的影响,又可以方便树的变形计算;另一方面,根据树的层次结构特点,新方法对树的各个部分分别进行独立的变形计算,然后再根据它们的连接关系进行组合,完整地获得树的变形．新方法对于小振幅的非末梢枝条,是利用静力分析来计算它们的变形,而对于振幅大的末梢枝条则采用Newmark逐步积分法求解其振动方程,这样就可以以较少的计算开销获得变形真实感很强的结果．在对树的各种姿态进行成像时,新方法运用了基于硬件的shadow mapping技术和LOD(Level-Of-Details)技术,以快速生成高度真实感的树．实验表明,对于有近4万个控制节点、近90万个拟合外观模型的三角形的柳树模型,新方法可以对其自然摇曳进行每秒0．6帧的高度真实感的模拟．