CAREER: Reusable, Realistic Motion Libraries for Computer Animation

动画是一种非常强大的表达媒介。用静止的图像或文字来表达那些复杂甚至不可能表达的想法，可以很容易地通过动画序列来传达。不幸的是，即使通过动画传达的概念很简单，制作动画的过程也异常困难。事实上，这也是计算机动画如此占据主导地位的原因之一--它有望实现制作过程的自动化，从而显著简化制作过程。遗憾的是，将创意转化为计算机动画的过程仍然很不简单。例如，动画片《玩具总动员2》需要200名高技能的计算机和动画专家花三年多的时间非常努力地工作。我的职业目标是开发概念和算法，使之能够毫不费力地、快速地开发出有效传达创作者意图的现实主义动画。这项研究希望为建立比现在更强大的动画工具奠定理论和实验基础。这样的工具将大大减少熟练动画师所需的制作时间，更重要的是，使普通计算机用户能够通过动画表达他们的想法。这样的工具还将帮助教育者更有效地进行教学，并让我们每个人都成为个人和虚构故事的创作者和导演。只有当动画制作变得更容易时，动画才会像今天的图像和文本一样在网络上司空见惯。此外，用于创建真实人体运动的直观方法将进一步支持在远程呈现应用中创建人类化身、新的拟人化的人机接口以及在故事片和视频游戏中创建逼真的数字演员。计算机动画将不会充分发挥其潜力，直到1)动画工具需要很少的技能或不需要技能，2)动画师的创造性不被动画工具的限制所扼杀，3)动画系统对每个拥有计算机和故事的人都是可用的。我希望为这些目标做出重大贡献。这项研究的核心是观察到，在制作逼真的动作序列变得更容易之前，动画师的创造力不会完全实现。这个问题极具挑战性，因为底层的运动物理模型很难创建和控制。我认为解决方案在于创建高度灵活的逼真动作库，以及直观和广泛地修改它们的工具。库的力量来自于重复使用已经存在的高质量动作的能力，减少了对动画技能的需求。在这个范例中，动画的过程转变为选择特定的运动库，并修改一组将原始运动转换为最终动画的运动属性。在我的研究中，我建议开发一种方法来创建和使用足够灵活的真实感运动库，以便在广泛的应用中使用。1995年，我提出了使用运动变换作为创建动画的新方法--一种与传统的从头开始创建动画的方法根本不同的方法。这种变换方法对于修改从现实世界中的演员捕获的逼真的运动数据特别有用。不幸的是，在转型过程中，许多现实主义往往会丢失。最近，我发表了一种新的变换方法，该方法证明了在不违反运动的基本动力学属性的情况下，可以直观地将动画变换成广泛的新序列。通过保持动画角色的动态和生物力学特性的模型来保持真实感。在未来，我将进一步开发可以与真实世界数据相结合的数学模型，以创建可重复使用的情感库。除了保持动作的真实感外，对有效的动画库最重要的要求是可以灵活地调整库以满足动画师的需求。我计划通过将角色的动作分解为基本组件和样式组件来实现这种灵活性，这样我们就可以独立地将这些组件转移到新角色上。例如，动画师可以从从捕获的人类跑步中提取的RunningMotion库开始，生成Achild欢快的跑步序列。这一动作可以通过应用快乐、活跃的动作风格来修改，然后将其转换为一个小孩子的动画角色。这种基本动作、风格和表演角色的分离提供了一个极其强大和灵活的动画范例，可以从非常小的动作数据集生成广泛的动画。本提案的教育部分的主要目标是演示高级动画工具在教育和讲故事中的效用。我特别感兴趣的是向西雅图的高中生介绍这些新的动画工具，以验证我们的研究确实赋予了每一位讲故事的人以易于理解的表达媒介的能力。我还计划开设一门以项目为导向的动画课程，面向从事动画研究、艺术和音乐的本科生和研究生。学生们将一起使用我们的工具来创作一个艺术短片项目。这一协同工作将使艺术家接触到最新的动画技术，并向参与研究的学生提供直接的用户反馈。此外，创建的动画库以及动画工具将通过网络和光盘免费分发，希望它们将有助于动画制作成为跨越教育、经济和文化界限的有效交流媒介。

Animation is a tremendously powerful medium of expression.Ideas that would be complex or even impossible to expresswith still images or words can easily be conveyed usinganimated sequences. Unfortunately, even when the concept tobe conveyed via animation is simple, the process ofproducing the animation is inordinately difficult. Indeed,this is one of the reasons computer animation has become sodominant - it holds the promise of automating, and thussignificantly simplifying, the production process. Sadly,the process of transferring ideas into computer animationsis still far from simple. For example, the animated featurefilm Toy Story 2 required extremely hard work by as many as200 highly skilled computer and animation experts for morethan three years.My career goal is to develop the concepts and algorithmsthat will enable effortless, rapid development of realisticanimations that effectively convey the creator's purpose.This research hopes to create the theoretical andexperimental foundation for building much more powerfulanimation tools than exist today. Such tools will sharplyreduce the production time needed by skilled animators and,more importantly, enable average computer users to expresstheir ideas through animation. Such tools will also helpeducators teach more effectively and allow each one of us tobecome creators and directors of personal and fictionalstories. Only when animation production is easier willanimation be as commonplace on the web as images and textare today. Moreover, intuitive methods for creatingrealistic human motion will further enable the creation ofhuman avatars in tele-presence applications, newanthropomorphic human-computer interfaces, and realisticdigital actors in feature films and video games. Computeranimation will not achieve its full potential until 1)animation tools require little or no skill, 2) an animator'screativity is not stifled by the limitations of theanimation tools, and 3) the animation systems are availableto every person with a computer and a story to tell. I hopeto significantly contribute towards these goals.At the heart of this research is the observation that theanimator's creativity will not be fully realized until itbecomes easier to produce realistic motion sequences. Thisproblem is tremendously challenging because the underlyingphysical models of motion are difficult to create andcontrol. I believe that the solution lies in the creation ofhighly-flexible realistic motion libraries, together withtools to modify them intuitively and extensively. The powerof libraries stems from the ability to reuse alreadyexisting high-quality motion, reducing the need foranimation skills. In this paradigm, the process of animationturns into selecting the specific motion library, andmodifying a set of motion properties that transform theoriginal motion into a final animation.In my research, I propose to develop a methodology forcreating and using realistic motion libraries flexibleenough to be used in a wide range of applications. In 1995,I proposed the use of motion transformation as new way tocreate animations - a method fundamentally different fromthe traditional way of creating animations from scratch.This transformation approach is particularly useful formodifying realistic motion data captured from real-worldactors. Unfortunately, during the transformation process,much of the realism tends to be lost. Recently, I publisheda novel transformation approach which demonstrates thatanimations can be intuitively transformed into a wide rangeof new sequences without violating the fundamental dynamicproperties of motion. The realism is preserved bymaintaining a model of the dynamic and biomechanicproperties of the animated character.In the future, I will further develop mathematical modelsthat can be combined with real-world data to create reusablemotion libraries. Aside from preserving the realism ofmotion, the most important requirement for effective motionlibraries is the flexibility with which the libraries can beadjusted to meet the needs of an animator. I plan to achievethis flexibility by decomposing a character's motion into afundamental component and a style component in a waythat allows us to independently transfer these components tonew characters. For example, the animator can produce achild's cheerful run sequence by starting with a runningmotion library extracted from the captured human run. Thismotion can be modified by applying a happy, exuberant motionstyle, which is then transferred to an animated character ofa small child. Such decoupling of the fundamental motion,style, and performing character provides an extremelypowerful and flexible animation paradigm that can produce awide range of animations from a very small motion dataset.The main goal of the educational component of this proposalis to demonstrate the utility of advanced animation tools ineducation and story-telling. I am particularly interested inintroducing these new animation tools to Seattle high-schoolstudents to verify that our research does indeed empowerevery story-teller with an accessible medium of expression.I am also planning a project-oriented animation courseintended for undergraduate and graduate students involved inanimation research, as well as in art and music. Together,the students will work on using our tools to create anartistic short film project. This synergistic effort willexpose the artists to the latest animation technology andprovide direct user feedback to students involved inresearch. In addition, the created motion libraries as wellas the animation tools, will be freely distributed throughthe web and CDs with the hope that they will help animationbecome an effective communication medium across educational,economic and cultural boundaries.