中文摘要：

三维模型外观瑕疵模拟一直是真实感绘制中的热点问题. 为了增强自然环境下场景的真实感, 提出一种模拟被雨流冲刷三维模型外观的方法. 首先提出三维模型在自然环境中的暴露程度、三维模型表面法向与污染源方向对模型表面的污染程度的定义, 并对污渍堆积进行模拟; 然后针对三维模型表面高斯曲率与平均曲率确定凹凸区域;最终剔除凸区域的污渍并绘制凹区域的污渍, 模拟雨流冲刷后的表面. 将文中方法应用到多个三维模型进行实验并与其他方法进行比较的结果表明, 该方法对于模拟被雨水冲刷三维模型的外观简单、可行, 并且具有很强的真实感.

英文摘要：

3D model blemishes simulation has always been a hot issue in the research of photo-realistic rendering.In this paper, we propose a method to simulate the appearances of the 3D models washed by the rain. Firstly, wedefines the exposure degree of the 3D models in the natural environment and the contamination degree of the appearancesof the 3D models influenced by the surface normal and the direction of the pollution sources. And thenwe simulate the phenomenon of dust accumulation on the model appearance. Thirdly, the mean curvature andGaussian curvature are analyzed to determine the convex and concave areas. Finally, we remove the stains in theconvex region and render the stains in the concave area to simulate the appearance of 3D models washed by therain. We apply our method to more 3D models. Compared with others methods, ours is more practical, simplerand has a stronger sense of reality.