Research Of Diffusion Effects In Painting CAD

Nowadays, the development of painting CAD systems becomes more and more rapidly. In this technical report, we present a generic and novel model traditional painting CAD system that captures a wide range of styles of all dry and wet strokes.The system includes a novel and fast brush model to reach implement various stroke-styles of traditional CAD painting; and it could be bent by pressing, folding, or wrinkling according to the user's operation. But its design of the 3D brush is a simplified one as we avoid much of the subtle brush display work. Besides, we promote a simple ink diffusion method and implement it on GPU (not very expensive). Thus we derive real time painting experience for users. Our method for ink diffusion is based on Fick's diffusion law but imposes our own boundary assertion; it can produce a number of various painting effects, with a certain degree of "anisotropism". In the final case, we study the 12 kinds of most commonly used pigments and calculate their scattering and absorbing coefficients for further realistic rendering.