以Lattice Boltzmann Method為基礎的NPR水彩繪畫模擬

Abstract

Non-Photorealistic Rendering (NPR) has been an important research topic in the field of Computer Graphics. Instead of highlighting the realism of CG synthesized images, NPR focus on the representation of the stroke and painter’s style. For the research of NPR watercolor, simulating water diffusion and flow in paper is an important task. In this paper, we implement a NPR watercolor system. Our scene is composed with 3D models. The special visual effects of watercolor paintings are created by simulating the color mixing and the different concentration of watercolor. To achieve the above goal and the “Brush-Washing” effect, the water flow on 2D paper is simulated based on the Lattice Boltzmann Method (LBM). Moreover, the strokes of watercolor are simulated by utilizing the auxiliary bone structures and the shapes of three-dimensional models. A stroke consists of multiple pixels. The color on each pixel is calculated by Phong’s reflection model. Therefore, the color on a stroke gradually transits from pixel to pixel. This approach creates nature and vivid appearances of strokes. In another word, our proposed method creates the tone of strokes automatically based on the 3D information of scene. As shown in the experiment results, our system synthesizes watercolor NPR animation with interesting and nature color, tone and strokes.