Abstract: This paper proposes a new periodic dynamic speech balloons generation method, which provides a new feature to show mood expressions in comics, games and some interactive applications. It presents a mathematic model, which represents a dynamic speech-balloon as the sum of a fixed base curve and a dynamic curve. Every control point of the dynamic curve is represented by a set of Fourier coefficients, and hence the periodic dynamics can be generated by Fourier synthesis. Then, it shows various rendering styles for dynamic speech-balloons rendering in real-time. In addition, it introduces a brush tool with various dynamic templates to intuitively create and edit the mathematic models of dynamic speech balloons. Finally, it presents a prototype system and experimental results demonstrate the effectiveness of the proposed method.

Key words: speech balloons, Fourier series, parametric curves, animation, cartoon

摘要： 动态对白框是动漫、游戏及社交应用中新出现的一种气氛烘托手法，但相关的研究还非常匮乏。为此提出了周期性动态对白框的数学模型，并研究了它的呈现及编辑技术。将动态对白框表达为固定基线和动态曲线的叠加，其动态曲线的每个控制点都表达为一组傅里叶系数，并通过傅里叶合成的方式实现周期性的动态效果。提出了多种对白框的渲染风格，以实现多种实时呈现效果。提出了主题模板和笔式编辑工具，为用户提供直观的方式以编辑、创作包含大量参数的周期性动态对白框模型。实现了周期性动态对白框原型创作系统，并构造出多种动态对白框特效，验证了该技术可实现新颖的、多样化的气氛烘托效果。

关键词: 对白框, 傅里叶级数, 参数曲线, 动画, 卡通