动画演示与算法教学研究

算法向来就是计算机教学中的难点，一般算法教学方法很难有效帮助学生理解算法。通过分析算法动画演示的认知作用，强调只有好的算法动画演示才能有效促进算法学习，然后从认知主体需要出发，提出设计好算法动画演示的四个原则。说明只有认真调查研究每一个算法的演示目标和重点，合理安排演示内容和形式，才能设计出一个好的算法动画演示系统。     

Designing Animated Transitions to Convey Aggregate Operations

Data can be aggregated in many ways before being visualized in charts, profoundly affecting what a chart conveys. Despite this importance, the type of aggregation is often communicated only via axis titles. In this paper, we investigate the use of animation to disambiguate different types of aggregation and communicate the meaning of aggregate operations. We present design rationales for animated transitions depicting aggregate operations and present the results of an experiment assessing the impact of these different transitions on identification tasks. We find that judiciously staged animated transitions can improve subjects' accuracy at identifying the aggregation performed, though sometimes with longer response times than with static transitions. Through an analysis of participants' rankings and qualitative responses, we find a consistent preference for animation over static transitions and highlight visual features subjects report relying on to make their judgments. We conclude by extending our animation designs to more complex charts of aggregated data such as box plots and bootstrapped confidence intervals.     

浅析中国本土戏曲角色与动画角色的融合

20世纪申后期,中国有很多经典的极富艺术魅力的动画角色一直印在我们的脑海中。像美猴王、葫芦娃、九色鹿、神笔马良、阿凡提等,角色造型风格各异。让人印象深刻。而如今大量动画作品在风格上跟风日美的痕迹,国产动画一定程度上失去了自己原有的民族性风格。进入新世纪。动画创作者开始尝试一些新的艺术手段来创作动画．而中国的传统戏曲具有独特的东方审美价值和艺术魅力,时值今日,动画工作者们一直都在尝试使用各种各样的艺术方式来进行动画创作。中国的戏曲文化博大精深。我们生活在这样一个文化氛围中。创作出具有本土文化特色的戏曲动画和塑造中国戏曲动画角色是万众期待的。     

Easy-to-use authoring system for Noh (Japanese traditional) dance animation and its evaluation

Noh is a genre of Japanese traditional theater, a kind of musical drama. Similar to other dance forms, Noh dance (shimai) can also be divided into small, discrete units of motion (shosa). Therefore, if we have a set of motion clips of motion units (shosa), we can synthesize Noh dance animation by composing them in a sequence based on the Noh dance notation (katatsuke). However, it is difficult for researchers and learners of Noh dance to utilize existing animation systems to create such animations. The purpose of this research is to develop an easy-to-use authoring system for Noh dance animation. In this paper, we introduce the design, implementation, and evaluation of our system. To solve the problems of existing animation systems, we employ our smart motion synthesis technique to compose motion units automatically. We improved the motion synthesis method by enhancing the algorithms for detecting body orientation and constraints between the foot and ground to handle Noh dance motions correctly. We classify motion units as either pattern units, which are specific forms of motion, represented as shot motion clips, or locomotion units, generated on the fly to denote movement towards a specific position or direction. To handle locomotion-type motion units, we implemented a module to generate walking motion based on a given path. We created several Noh dance animations using this system, which was evaluated through a series of experiments. We also conducted a user test to determine the usefulness of our system for learners of Noh dance.     

A Study of the Effect of Doughnut Chart Parameters on Proportion Estimation Accuracy

Pie and doughnut charts nicely convey the part–whole relationship and they have become the most recognizable chart types for representing proportions in business and data statistics. Many experiments have been carried out to study human perception of the pie chart, while the corresponding aspects of the doughnut chart have seldom been tested, even though the doughnut chart and the pie chart share several similarities. In this paper, we report on a series of experiments in which we explored the effect of a few fundamental design parameters of doughnut charts, and additional visual cues, on the accuracy of such charts for proportion estimates. Since mobile devices are becoming the primary devices for casual reading, we performed all our experiments on such device. Moreover, the screen size of mobile devices is limited and it is therefore important to know how such size constraint affects the proportion accuracy. For this reason, in our first experiment we tested the chart size and we found that it has no significant effect on proportion accuracy. In our second experiment, we focused on the effect of the doughnut chart inner radius and we found that the proportion accuracy is insensitive to the inner radius, except the case of the thinnest doughnut chart. In the third experiment, we studied the effect of visual cues and found that marking the centre of the doughnut chart or adding tick marks at 25% intervals improves the proportion accuracy. Based on the results of the three experiments, we discuss the design of doughnut charts and offer suggestions for improving the accuracy of proportion estimates.     

浅析Open Flash Chart的使用

Open Flash Chart是基于Web网络应用图表技术,用简单方便配置提供出绚丽动画效果,并且图表类型丰富多彩、数据文件结构清晰而明了。通过Open Flash Chart可以生成线图、饼状图、柱状图、雷达图、区域图以及组合图表等,设定颜色、字体、背景等CSS样式,为用户提供了大量可选择的数据图表显示方式。     

Reverse‐Engineering Visualizations: Recovering Visual Encodings from Chart Images

We investigate how to automatically recover visual encodings from a chart image, primarily using inferred text elements. We contribute an end‐to‐end pipeline which takes a bitmap image as input and returns a visual encoding specification as output. We present a text analysis pipeline which detects text elements in a chart, classifies their role (e.g., chart title, x‐axis label, y‐axis title, etc.), and recovers the text content using optical character recognition. We also train a Convolutional Neural Network for mark type classification. Using the identified text elements and graphical mark type, we can then infer the encoding specification of an input chart image. We evaluate our techniques on three chart corpora: a set of automatically labeled charts generated using Vega, charts from the Quartz news website, and charts extracted from academic papers. We demonstrate accurate automatic inference of text elements, mark types, and chart specifications across a variety of input chart types.     

Using animation to help students learn computer algorithms

This paper compares the effects of graphical study aids and animation on the problem-solving performance of students learning computer algorithms. Prior research has found inconsistent effects of animation on learning, and we believe this is partly attributable to animations not being designed to convey key information to learners. We performed an instructional analysis of the to-be-learned algorithms and designed the teaching materials based on that analysis. Participants studied stronger or weaker text-based information about the algorithm, and then some participants additionally studied still frames or an animation. Across 2 studies, learners who studied materials based on the instructional analysis tended to outperform other participants on both near and far transfer tasks. Animation also aided performance, particularly for participants who initially read the weaker text. These results suggest that animation might be added to curricula as a way of improving learning without needing revisions of existing texts and materials. Actual or potential applications of this research include the development of animations for learning complex systems as well as guidelines for determining when animations can aid learning.     

Flash动画短片的制作

Flash是当今Internet上最流行的动画作品制作工具,是一种交互式动画设计工具,可以制作丰富多彩的矢量动画,并且用它可以将音乐、声效、动画以及富有新意的界面融合在一起,以制作出高品质的动画效果。通过掌握二维动画短片的设计与制作原理,结合Flash软件进行二维动画短片的设计与制作,完成从初期的剧本创意,造型、场景设计,绘制脚本、设计稿、元件,到最终在Flash软件中实现二维动画短片。     

黑白图像的矢量化

通过向Ｉｎｔｅｒｎｅｔ网页中加入质量高、制作精美的动画,可以增加网页的生动性,提高其表现力。Ｉｎｔｅｒｎｅｔ上的一些应用,如远程教学等,也需要通过大量的动画来提高质量,增强效果,而用以往的动画制作系统所制作的动画的数据量往往很大,经Ｉｂｎｔｅｒｎｅｔ传送所需时间之长令人难以忍受,新的动画制作系统多使用矢量菜进行动画制作,为使动画制作更加方便,提高制作效率,希望能通过某种手段自动完成图像矢量化,针对     

A relation-based model for animating adaptive behavior in dynamicenvironments

Over the past few decades many advances have been made in computer animation, which has largely replaced traditional hand-drawn animation. However, the traditional path model used in animation has not changed. This model as based on predefined paths does not effectively address the needs of scene animation, which demands unpredictable environmental influences, multiple motion interactions, and personal behaviors. Some of the suggested approaches to scene animation are sensor-effector model, rule-based model, and predefined environment model, but these approaches don't completely solve the problem. This paper presents a relation-based model for dealing with the important issues of scene animation. Two fundamental principles of our model are: the specification of atomic units of motion (relations), and the ability to combine these atomic units to produce sophisticated behaviors. Each relation models a simple responsive behavior between two objects, and has its own sensor, response, duration, strength, and state. The dynamic states of relations can be interactively structured into hierarchical layers that produce complex scene behaviors. During the animation, structured relations are dynamically triggered by either its sensing condition(s) or the state of the environment. The variable state-control hierarchies facilitate on-line scene behavior animations. Several dancing examples for the use of our model are illustrated     

Reusing view-dependent animation

In this paper we present techniques for reusing view-dependent animation. First, we provide a framework for representing view-dependent animations. We formulate the concept of a view space, which is the space formed by the key views and their associated character poses. Tracing a path on the view space generates the corresponding view-dependent animation in real time. We then demonstrate that the framework can be used to synthesize new stylized animations by reusing view-dependent animations. We present three types of novel reuse techniques. In the first we show how to animate multiple characters from the same view space. Next, we show how to animate multiple characters from multiple view spaces. We use this technique to animate a crowd of characters. Finally, we draw inspiration from cubist paintings and create their view-dependent analogues by using different cameras to control different body parts of the same character.     

Animation toolkit based on a database approach for reusing motions and models

As animations become more readily available, simultaneously the complexity of creating animations has also increased. In this paper, we address the issue by describing an animation toolkit based on a database approach for reusing geometric animation models and their motion sequences. The aim of our approach is to create a framework aimed for novice animators. Here, we use an alternative notion of a VRML scene graph to describe a geometric model, specifically intended for reuse. We represent this scene graph model as a relational database. A set of spatial, temporal, and motion operations are then used to manipulate the models and motions in an animation database. Spatial operations help in inserting/deleting geometric models in a new animation scene. Temporal and motion operations help in generating animation sequences in a variety of ways. For instance, motion information of one geometric model can be applied to another model or a motion sequence can be retargeted to meet additional constraints (e.g., wiping action on a table can be retargeted with constraints that reduce the size of the table). We present the design and implementation of this toolkit along with several interesting examples of animation sequences that can be generated using this toolkit.     

基于形变模型的真实感三维人脸动画研究

论文提出了一种新的基于三维人脸形变模型,并兼容于MPEG-4的三维人脸动画模型。采用基于均匀网格重采样的方法建立原型三维人脸之间的对齐,应用MPEG-4中定义的三维人脸动画规则,驱动三维模型自动生成真实感人脸动画。给定一幅人脸图像,三维人脸动画模型可自动重建其真实感的三维人脸,并根据FAP参数驱动模型自动生成人脸动画。     

基于线型草图的多源3维动画传输

为了对3维动画进行鲁棒地传输,提出了一种基于线型草图的3维动画传输方法,该方法可以把多个源网格的动画传输到一个目标网格。该方法由以下几个步骤组成:(1)使用线型草图在源网格和目标网格间建立映射;(2)使用差分均值坐标(differential mean value coordinates),根据源动画来变形目标网格;(3)对齐各部分变形后的目标网格,通过求解最小化约束函数,以获取光滑的目标网格,从而生成目标动画的关键帧;(4)对由步骤(3)产生的结果进行插值,即可产生完整的目标对象的3维动画。通过对上述几个方面的深入研究,以及将这些成果集成在原型系统中的结果表明,该方法具有以下特点:①既不需要源网格和目标网格有相同的顶点数和三角面片数,也不需要有类似的拓扑信息;②源动画既可以是3维的,也可以是2维视频或Flash;③目标对象可以是无结构化的点云数据。实践表明,该方法直观易用,可以生成逼真的3维动画。最后通过从狗、猫、蛇、人体的3维动画与2维车轮视频的合成来产生复杂的马车动画,对该方法进行了验证。另外,原型系统还通过产生其他几个例子来进一步验证其通用性和鲁棒性。     

Sketching 3D Animations

We are interested in providing animators with a general-purpose tool allowing them to create animations using straight-ahead actions as well as pose-to-pose techniques. Our approach seeks to bring the expressiveness of real-time motion capture systems into a general-purpose multi-track system running on a graphics workstation. We emphasize the use of high-bandwidth interaction with 3D objects together with specific data reduction techniques for the automatic construction of editable representations of interactively sketched continuous parameter evolution. In this paper, we concentrate on providing a solution to the problem of applying data reduction techniques in an animation context. The requirements that must be fulfilled by the data reduction algorithm are analyzed. From the Lyche and Mørken knot removal strategy, we derive an incremental algorithm that computes a B-spline approximation to the original curve by considering only a small piece of the total curve at any time. This algorithm allows the processing of the user's captured motion in parallel with its specification, and guarantees constant latency time and memory needs for input motions composed of any number of samples. After showing the results obtained by applying our incremental algorithm to 3D animation paths, we describe an integrated environment to visually construct 3D animations, where all interaction is done directly in three dimensions. By recording the effects of user's manipulations and taking into account the temporal aspect of the interaction, straight-ahead animations can be defined. Our algorithm is automatically applied to continuous parameter evolution in order to obtain editable representations. The paper concludes with a presentation offuture work.     

Self adaptive animation based on user perspective

In this paper we present a new character animation technique in which the animation adapts itself based on the change in the user’s perspective, so that when the user moves and their point of viewing the animation changes, then the character animation adapts itself in response to that change. The resulting animation, generated in real-time, is a blend of key animations provided a priori by the animator. The blending is done with the help of efficient dual-quaternion transformation blending. The user’s point of view is tracked using either computer vision techniques or a simple user-controlled input modality, such as mouse-based input. This tracked point of view is then used to suitably select the blend of animations. We show a way to author and use such animations in both virtual as well as augmented reality scenarios and demonstrate that it significantly heightens the sense of presence for the users when they interact with such self adaptive animations of virtual characters.     

An approach to effortless construction of program animations

Program animation systems have not been as widely adopted by computer science educators as we might expect from the firm belief that they can help in enhancing computer science education. One of the most notable obstacles to their adoption is the considerable effort that the production of program animations represents for the instructor. We present here an approach to reduce such a workload based on the automatic generation of visualizations and animations. The user may customize them in a user-friendly way to construct more expressive program animations. These operations are carried out by means of a user-friendly manipulation based on the metaphor of office documents. We have applied this approach to the functional paradigm by extending the WinHIPE programming environment. Finally, we report on the successful results of an evaluation performed to measure its ease of use.     

Automatic Conversion of Mesh Animations into Skeleton-based Animations

Recently, it has become increasingly popular to represent animations not by means of a classical skeleton‐based model, but in the form of deforming mesh sequences. The reason for this new trend is that novel mesh deformation methods as well as new surface based scene capture techniques offer a great level of flexibility during animation creation. Unfortunately, the resulting scene representation is less compact than skeletal ones and there is not yet a rich toolbox available which enables easy post‐processing and modification of mesh animations. To bridge this gap between the mesh‐based and the skeletal paradigm, we propose a new method that automatically extracts a plausible kinematic skeleton, skeletal motion parameters, as well as surface skinning weights from arbitrary mesh animations. By this means, deforming mesh sequences can be fully‐automatically transformed into fullyrigged virtual subjects. The original input can then be quickly rendered based on the new compact bone and skin representation, and it can be easily modified using the full repertoire of already existing animation tools.