Synthesis of Handwriting Dynamics using Sinusoidal Model

Handwriting production is a complex mechanism of fine motor control, associated with mainly two degrees of freedom in the horizontal and vertical directions. The relation between the horizontal and vertical velocities depends on the trajectory shape and its length. In this work, we explore the generation of handwriting velocities using two sinusoidal oscillations. The proposed method follows the motor equivalence theory and considers that the patterns are stored in the form of a sequence of corner shapes and its relative location in the letter. These points are referred to as the modulation points, where the parameters of the sinusoidal oscillations are modulated to generate required velocity profiles. Depending on the location and shape of the corners, the amplitude, phase, and frequency relations between the two underlying oscillations are changed. Accordingly, this paper presents an efficient method to synthesize the velocity profiles and hence the handwriting. Further, the shape variability in the synthesized data can also be introduced by modifying the position of the modulation points and its corner shapes. The quality of the synthesized handwriting is evaluated using both subjective and quantitative evaluation methods.