基于形状控制函数和自适应细分的皱纹建模方法

逼真的皱纹模型能极大地提高三维人脸建模的相似度。为获得精确位置和形状的三维皱纹曲线,运用基于特征的图像匹配方法使二维图像和三维模型匹配对齐。针对皱纹3个方向视图的不同形状,分别提出3个形状控制函数,即皱纹横截面形状控制函数、深度衰减函数和宽度衰减函数。横截面形状控制函数能真实自然地表达皱纹截面的凹形纹路和两边圆形凸起,深度和宽度衰减函数分别控制皱纹深度方向和宽度方向的衰减程度。用户只需定义几个直观的参数便能生成各种形状的皱纹模型。此外,提出一种皱纹影响区域的定义方法和网格自适应细分技术,不仅保证了皱纹建模的效果,而且能提高建模效率。通过实验结果与照片的对比,表明本文方法能生成各种真实自然的皱纹,对人脸建模的相似度有很大提高。

Wrinkle modeling based on shape control functions and adaptive subdivision

Realistic wrinkles are an extremely important contribution for enhancing the realism of three dimensional (3D) face model.For different shapes of the wrinkle in three views, this paper proposes three shape control functions for each view, namely, cross-sectional shape control function (CSCF), depth attenuation function (DAF) and width attenuation function (WAF).CSCF is used to realistically and naturally express the furrows and bulges of wrinkles. Depth attenuation function and width attenuation function are applied to control the attenuation variations of the depth and width. Users can create various wrinkles just defining several intuitive parameters. Meanwhile, an image matching technique based on feature is employed to obtain three dimensional wrinkle lines. And a simple adaptive subdivision approach is proposed in the predefined influence region to adjust the resolution around the wrinkle mesh for better results and enhance the efficiency of wrinkle modeling simultaneously. Comparing experiment results with the corresponding image demonstrates that our method can generate realistic and natural wrinkles and can greatly improve the similarity of face model.