In computer graphics (CG), there are various efforts to generate plausible paint effects. However, many previous researches studies have focused on the representation of specific types of paint effects in the domain of non-photorealistic rendering (NPR), even though paint effects are naturally generated by complicated physical laws in the real world.
Moreover, they do not account for the relationship or the interaction between painting components such as binder, solvent, pigment, and paper. The process of absorption of a fluid by a paper also has been largely neglected.
In this dissertation, we present a new method to create realistic paint simulation, utilizing the characteristics of paint, such as fluidity, diffusion, and absorption. At the start point of the research, we observe the process of real painting for designing a paint simulation system. From the observation, we treat the painting elements separately as pigment, binder, solvent, and paper. Adopting smoothed-particle hydrodynamics (SPH), we simulate the fluid motion of the paint and the solvent. We apply viscoelastic force to the binder of the paint because paint is a classic example of a viscoelastic fluid. The viscoelastic movement of the paint generates more realistic paint simulation. To handle the diffusion of the pigment in the solvent, we utilize the mass transfer method. Following Fick`s law, the concentration of pigment changes and they are diffused to the neighbor particle accordingly. During the diffusion in the real world, the pigments spread out irregularly in the fluid. To express the situation, we utilize the curvature based diffusion coefficient. As time elapses, the binder and the solvent are absorbed and, for the most part, the pigment remains on the paper. The Lucas-Washburn equation determines the distance of absorption.
Based on the paint simulation, we apply the specific rendering methods to enhance the visual characteristics of the painting. To generate the paint and binder ...