基于纹理映射的中国水墨画“干笔飞白”效果的仿真生成

Realization of the Half-Dry Stroke Effect in Chinese Ink-Wash Drawing Based on Texture Mapping

针对中国水墨画“干笔飞白”效果的独特纹理和复杂形状,提出了曲底边四边形的概念和两种笔道表示法:“中心线关键点”表示法、“轮廓线关键点”表示法,并重点研究了从矩形到曲底边四边形的区域映射算法.首先将笔道分割为多个曲底边四边形,应用映射算法和拼合技术,把画家的经典“飞白”笔触绘制为笔道内部纹理.新的笔道表示法和笔道分割机制,使得算法复杂度小、性能高.仿真结果表明,绘制效果既保留了原笔触的纹理特性,又准确贴合了笔道轮廓,整体效果逼真生动.

Half-dry stroke has a special effect in Chinese ink-wash drawing. To simulate its special texture and complex shape, a new concept of quadrilateral with two opposite curve sides (QTOCS) and two representations of dividing strokes (centre-line-key-point-representation and outline-key-point-representation) are presented according to the irregularity of the texture and shape of half-dry strokes. The emphasis is placed on the design of the algorithm of mapping QTOCS to rectangle. First a stroke is divide into several QTOCSs,and then by using the mapping algorithm and attaching technology, the internal texture of the stroke is rendered with drawers′ classic style of drawing. The new representations and mechanism of dividing strokes make the algorithm little complex and excellent in performance. The simulated results indicate that the rendering effect is very lifelike, not only keeping the characteristics of original drawing, but jointing the outlines of strokes correctly.