从明暗恢复形状的手绘草图三维建模算法  

Sketch Based Modeling Algorithm Using Shape from Shading

作　　者：谢浩[1] 费广正[2] 吴明峰[1] 李欣[1] 孙国玉[2] 

机构地区：[1]中国传媒大学计算机与软件学院,北京100024 [2]中国传媒大学动画学院,北京100024

出　　处：《工程图学学报》2006年第4期57-65,共9页Journal of Engineering Graphics

基　　金：国家自然科学基金资助项目(60403037)

摘　　要：提出一种通过用户手绘草图进行三维建模的算法,该算法直接利用二维笔触输入,实现简单、快捷的三维动画原型制作。首先从通过鼠标或手写板等绘制的自由曲线中析取包含手绘风格信息的结构化轮廓线,并在轮廓线所围区域中应用距离变换生成距离场;然后利用线性近似的方法从明暗恢复形状算法中获得三维曲面;接着对三维曲面进行对称、缝合和平滑变换得到基本的三维几何体;最后将基本几何体组合并进行编辑。算法强调手绘效果,提供所见即所得的交互风格,可广泛应用于三维动画和游戏的前期模型设计与制作,以及计算机辅助教学系统等领域。A sketch based algorithm for designing freeform models using the technique of Shape from Shading is provided. In the first step, the user drawn contour curve that forms a closed region in a representation called displaced subdivision curve. In the second step, a smooth distance field within the closed region is computed according to the shortest path of each inrerior point to the contour curve, where the distance field can be fine-tuned using some curve adjustment method. A model part is generated on top of the distance field using the technique of shape from shading in the third step. Finally a complete model is obtained by interactively assembling the individual parts generated in the previous steps. The algorithm emphasizes the style of handwriting, and the interactive style of ＇What You See Is What You Get＇. It can be widely used in 3D modeling of the animation, model designing in game and computer aided instruction （CAI） and so on.

关 键 词：计算机应用 建模 从明暗恢复形状 曲线重构 

分 类 号：TP391[自动化与计算机技术—计算机应用技术]