Constructing and reconstructing characters, words, and sentences by synthesizing writing motions

In this paper, we investigate the problem of generating and manipulating characters, words, and sentences. First, characters are obtained as the trace of the cross-sectional area between a virtual writing plane and a virtual writing device modeled by a circular cone, which is moving in a three-dimensional space. Such a motion is designed as a sum of weighted and time-shifted B-spline functions. A sequence of weight vectors called control points defines the so-called control polygon, and represents the motion and hence, a character. Characters or control polygons designed in this way are then connected in a systematic way to yield words and sentences, which again are represented as a control polygon, either small or large. Then, we consider transforming the typeface of characters or words to the omitted running styles as seen in Japanese calligraphy. Such a scheme is developed by formulating the problem as an optimal function-approximation problem, which minimizes an input energy of writing motions. Finally, a design example of cursive words is included and also the method is implemented for robotic handwriting. Thus, the paper provides a unified framework for generating and manipulating characters, words, and sentences, which are complex planar patterns, in a systematic as well as theoretically sound fashion. Although we describe the method using Japanese Kana characters, the idea and methodology for constructing and reconstructing characters and character strings is general and is not only limited to Japanese characters