融合手绘风格的卡通角色动画生成方法

手绘风格的卡通动画具有灵活、自然、表现力强等特点.为了快速地创作体现手绘风格的卡通角色动画,提出一种基于多视点手绘图的动画生成方法.首先利用手绘图构建角色的三维网格和骨架子空间模型;然后结合姿态重建和微分域网格变形算法,创建一组与多视点手绘图相匹配的视点相关模型,以表达手绘风格;最后通过运动标注和启发式泛化算法将手绘风格融入输入的运动序列,使生成的动画既保留运动序列的原始特征,又体现手绘图的笔画风格.实验结果表明,该方法能够有效地生成体现手绘风格的卡通角色动画.     

应用运动模糊方法仿真铅笔画纹理

通过分析真实铅笔纹理的特点,提出了一种基于运动滤波器的仿真铅笔纹理的新方法.首先对用户输入的图像进行边缘检测,提取轮廓信息,然后对传统白噪声生成法进行改进,将参考图像由RGB色彩空间转换到HSV色彩空间,通过亮度值控制噪声点的产生几率,最后应用运动模糊方法代替传统的线积分卷积(LIC)方法模拟铅笔纹理,得到具有素描风格的结果图像.实验结果表明,该方法生成效果接近于手绘风格,且无需用户交互,适合于动画制作等很多领域的应用.     

一种基于混合模型的实时虚拟人服装动画方法

实时服装动画生成技术能够为三维虚拟角色实时地生成逼真的服装动态效果,在游戏娱乐、虚拟服装设计展示等领域有着广泛的应用前景.其难点在于如何建立服装动画计算模型,在实时计算的前提下获得最佳的服装动画生成效果.在对服装模型与人体模型在运动过程中发生的位置冲突(collision,也称碰撞)进行分析的基础上,研究并提出了一种基于混合模型的实时虚拟人服装动画计算模型.首先,根据服装动画样本数据中服装与人体发生位置冲突的信息,对服装与人体的运动相关性进行分析;在此基础上,提出并实现一种新的混合策略,将具有较好服装动态模拟效果的动力学计算模型与具有较高计算效率的几何变形方法进行混合,建立支持实时计算且效率可动态控制的服装动画计算模型.实验结果表明,该计算模型能够实时地生成具有较好视觉逼真性的服装动画.     

手绘艺术动画的计算机辅助设计方法综述

近年来随着计算机技术广泛应用于手绘艺术动画的制作,出现了许多新的手绘艺术动画的计算机辅助设计和制作方法。这些方法概括为五类：①结合三维动画技术实现艺术动画制作;②引入中国传统的艺术元素制作手绘动画;⑧基于视频流生成动画;,④使用素材重用的方法制作手绘动画;⑤结合中间帧自动或半自动生成技术制作动画。文章对这些方法进行了介绍,并指出中间帧生成技术能够保持绘画者的手绘风格,突出手绘动画的艺术特征;并进一步说明了结合中间帧生成技术辅助制作动画的关键,是寻求一种自然高效的交互方式来定义始末关键帧中图形元素间的对应关系,以及根据此对应关系自动或半自动生成中间帧的方法。     

探究融合手绘风格的卡通角色动画生成方法

动画产业是我国最近几年兴起新兴产业,由目情况前来看,动画产业有发展成我国主流产业的态势。由此可见,动画越来越受国民的喜爱。而动画在制作过程中并没有预想的容易。实际上制作动画最基本的要求就是角色的动作神态都必须要自然、生动、灵活并且表现力要强,要想达到理想效果,制作过程是十分复杂繁琐的。但是如果将手绘风格融入到卡通角色动画中,那么效果就大不一样了。因此本文对融合手绘风格的卡通角色动画生成方法进行探究,期望得到真正有效的方法。     

一种铅笔画仿真新方法

通过分析铅笔画的艺术特点,提出一种基于图像的铅笔画仿真方法。首先对用户输入的图像进行Unsharp Mask（USM）锐化提取细节信息,并进行颜色放大处理以增强对比度,然后采用基于点的向量场技术生成笔画方向,最后应用线积分卷积（LIC）得到具有素描风格的结果图像。为了更好地模拟铅笔纹理,改进了传统的纹理生成方法,提出将锐化后的结果图像代替白噪声图作为LIC的输入。实验结果表明,该方法的生成效果更接近于手绘风格,且无需用户交互,适合于动画制作等很多领域的应用。     

综合多层语义特征与深度卷积网络的手绘图像检索方法

针对手绘图像检索领域中手绘图像的语义特征,为了深度发掘手绘图像的语义特征,并获得高效、准确的检索结果,提出一种基于多层语义特征和深度卷积网络的融合网络的方法.首先提出针对手绘图像语义特征的分层的概念,并构建与多层语义特征相对应的多层深度卷积神经网络来学习不同层次的深度特征,然后通过特征融合,实现多层深度语义特征的融合,形成最终的特征描述子,达到高精度的检索.在基准数据库Flickr15k上的实验结果表明该方法是可行、有效的.     

具有层次素描纹理的素描画绘制方法

针对现有的计算机非真实感绘制(NPR)技术关于素描画的绘制方法的实现效果与手绘风格存在一定差异的问题,设计了一种能够产生层次素描纹理的方法,并将其与多像素宽边缘线条融合,生成具有层次感素描纹理的素描画。首先对原始图像做去噪、增强等预处理,用微分算子提取多像素宽的轮廓线条;再通过膨胀和腐蚀处理并将结果相减生成多层双边轮廓线条,用运动模糊处理多层双边线条得到素描纹理;最后融合边缘和素描纹理,得到素描效果图像。通过对不同特点的图像进行实验,证明该方法得到的素描画的效果比较接近手绘风格。     

计算机生成剪纸风格流水动画

针对手工制作剪纸风格流水动画极其费工、费时的问题,提出一种用计算机手段生成剪纸风格流水动画的方法.首先对手工剪纸中的流水纹样进行分类,构建它们的静态结构模型,并对于各种类型的水波纹建立不同的动态控制机制;在生成流水动画时,对各种波纹在时空上进行有机组合,包括浪花纹在流水波纹上的出现位置与动态控制,以及在有移动物体情况下物体和水面交界处各种纹样的控制.采用文中系统,用户只需进行少量交互确定流水波纹的位置,便能生成运动流畅的剪纸风格流水动画.最后给出了平稳水波、激烈水波以及水上移动物体与水面相交流水波纹的动画图例.     

基于概要图的数字地形生成方法

针对地形生成算法在易用性、可控性、真实感、速度等方面难以平衡的问题, 提出了一种基于概要图的地形生成方法. 该方法使用生成对抗网络, 在隐空间中对地形坡度、坡向等信息建模, 使生成的地形符合用户手绘概要图约束. 提出基于地形高度图的概要图提取算法, 可从真实地形高度图中提取出类似用户手绘效果的概要图, 快速构建数据集. 提出多尺度地形细节填充算法, 通过引入多尺度的概念, 使地形纹理细节得到了动态补充, 真实感美观度大幅提升. 提出了基于用户反馈的地形满意度评价方法, 并据此进行实验验证, 结果表明该地形生成方法可以准确高效地生成符合用户预期的数字地形.     

Feature matching and affine transformation for 2D cell animation

This paper presents an application for feature matching and affine transformation in computer graphics. The study case considered is 2D cell animation, which is still a labor-intensive process in current cartoon film production. One key problem in automating 2D cell animation in inbetween frame generation. The objective of our work is to investigate how to automatically generate inbetweening from pairs of hand-drawn 2D key frames. Our technique first establishes the correspondence of feature points and then estimates the affine transformation between each pair of 2D key frames. The inbetween frames are then automatically generated by interpolation.     

一种快速的基于物理模型的织物模拟

提出了一种基于物理模型的实时动态模拟织物的方法。模拟织物的运动一直都是虚拟仿真的重要课题,在电影、游戏和虚拟现实中大量用到,但是逼真的模拟往往需要高昂的计算代价。文章通过对织物物理和几何属性分析。构造出一个带约束的物理模型。使用一种自适应的迭代法,最大限度地利用了局部时间和空间上的模拟参数,大大提高了计算的效率。并根据织物的物理特性,优化共轭梯度法,综合各种算法的优点,不断优化算法。可以实时地并且精确地模拟织物的运动。     

Kinect动作捕捉技术在三维动画教学中的应用与实践

针对传统三维角色动画制作成本高、时间长的问题,文章介绍了一种应用Kinect动作捕捉技术实现高效制作三维角色动画的方法。该方法借助Kinect体感摄像机捕捉真人的动作生成骨骼关节的关键帧数据并输出bvh动作路径文件,然后把bvh动作路径数据导入C4D软件中,就可以驱动角色模型完成角色动画的制作。把这种方法运用到三维角色动画教学实践中,有利于提高学生学习的兴趣和效率。     

Non-linear Rough 2D Animation using Transient Embeddings

Traditional 2D animation requires time and dedication since tens of thousands of frames need to be drawn by hand for a typical production. Many computer-assisted methods have been proposed to automatize the generation of inbetween frames from a set of clean line drawings, but they are all limited by a rigid workflow and a lack of artistic controls, which is in the most part due to the one-to-one stroke matching and interpolation problems they attempt to solve. In this work, we take a novel view on those problems by focusing on an earlier phase of the animation process that uses rough drawings (i.e., sketches). Our key idea is to recast the matching and interpolation problems so that they apply to transient embeddings, which are groups of strokes that only exist for a few keyframes. A transient embedding carries strokes between keyframes both forward and backward in time through a sequence of transformed lattices. Forward and backward strokes are then cross-faded using their thickness to yield rough inbetweens. With our approach, complex topological changes may be introduced while preserving visual motion continuity. As demonstrated on state-of-the-art 2D animation exercises, our system provides unprecedented artistic control through the non-linear exploration of movements and dynamics in real-time.     

Research problems in clothing simulation

Clothing simulation and animation are of great importance in computer animation. If cloth simulations could be improved to the point that they could generate realistic cloth motion in real-time, they would find uses in many aspects of daily life such as in fashion design and manufacturing. The area of cloth simulation and animation is full of technical challenges: creating more realistic results, achieving faster run-times, and developing methods capable of constructing and simulating more complex garments. This paper provides an overview of the key procedures involved in the creation of clothed characters, describes the current state-of-the-art techniques, and proposes the research problems that most require further study. Three technical aspects of cloth simulation are considered in this paper: garment construction, physically based simulation, and collision resolution.     

Animated 3D Line Drawings with Temporal Coherence

Producing traditional animation is a laborious task where the key drawings are first drawn by artists and thereafter inbetween drawings are created, whether it is by hand or computer‐assisted. Auto‐inbetweening of these 2D key drawings by computer is a non‐trivial task as 3D depths are missing. An alternate approach is to generate all the drawings by extracting lines directly from animated 3D models frame by frame, concatenating and rendering them together into an animation. However, animation quality generated using this straightforward method bears two problems. Firstly, the animation contains unsatisfactory visual artifacts such as line flickering and popping. This is especially pronounced when the lines are extracted using high‐order derivatives, such as ridges and valleys, from 3D models represented in triangle meshes. Secondly, there is a lack of temporal continuity as each drawing is generated without taking its neighboring drawings into consideration. In this paper, we propose an improved approach over the straightforward method by transferring extracted 3D line drawings of each frame into individual 3D lines and processing them along the time domain. Our objective is to minimize the visual artifacts and incorporate temporal relationship of individual lines throughout the entire animation sequence. This is achieved by creating correspondent trajectory of each line from each frame and applying global optimization on each trajectory. To realize this target, we present a fully automatic novel approach, which consists of (1) a line matching algorithm, (2) an optimizing algorithm, taking into account both the variations of numbers and lengths of 3D lines in each frame, and (3) a robust tracing method for transferring collections of line segments extracted from the 3D models into individual lines. We evaluate our approach on several animated model sequences to demonstrate its effectiveness in producing line drawing animations with temporal coherence.     

Comic character animation using Bayesian estimation

The motion of comic characters includes different types of movements, such as walking or running. In a comic, a movement may be described by a series of non‐continuous poses in a sequence of contiguous frames. Each pose exists in a frame. We synthesize an animation according to still comic frames. In this paper, we propose a model to analyze time series of a character's motion using the non‐parametric Bayesian approach. Then we can automatically generate a sequence of motions by using the estimated time series. Experimental results show that the built time series model best matches the given frames. Furthermore, unnatural distortions of the results are minimized. Copyright © 2011 John Wiley & Sons, Ltd.     

基于Kinect的人体姿态估计优化和动画生成

为了生成更准确流畅的虚拟人动画,采用Kinect设备捕获三维人体姿态数据的同时,使用单目人体三维姿态估计算法对Kinect的彩色信息进行骨骼点数据推理,从而实时优化人体姿态估计效果,并驱动虚拟人物模型生成动画。首先,提出了一种时空优化的骨骼点数据处理方法,以提高单目估计人体三维姿态的稳定性;其次,提出了一种Kinect和遮挡鲁棒姿势图（ORPM）算法融合的人体姿态估计方法来解决Kinect的遮挡问题;最后,研制了基于四元数向量插值和逆向运动学约束的虚拟人动画系统,其能够进行运动仿真和实时动画生成。与仅利用Kinect捕获人体运动来生成动画的方法相比,所提方法的人体姿态估计数据鲁棒性更强,具备一定的防遮挡能力,而与基于ORPM算法的动画生成方法相比,所提方法生成的动画在帧率上提高了两倍,效果更真实流畅。     

布料仿真技术在游戏中的设计和实现

近几年来,布料仿真技术广泛应用于游戏开发中,本文针对游戏在实时性和交互性方面的特殊需求,结合“网络游戏公共技术平台关键技术研究”项目,对布料的物理模型、模型求解以及碰撞检测和处理等方面进行了分析和设计,并在此基础上实现了几种布料动画的模拟。     

MA3D：三维造型动画系统的OOP实现

本文介绍了一个基于ＯＯＰ程序设计方法的三维造型动车集成系统，在该系统中，造型与动画具有统一的数据结构，系统提供的命令语言使得用户能够定义模型及其运动，系统输出的数据文件用以描述动画的每一帧画面，它们可以作为生成三维浓淡图的绘制程序的输入，从而生成三维动车画面。目前，系统提供了以线框图形式进行动画预演的工具。