Rapid Acquisition of Specular and Diffuse Normal Maps from Polarized Spherical Gradient Illumination
Rapid Acquisition of Specular and Diffuse Normal Maps from Polarized Spherical Gradient Illumination
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DOI：
10.2312/egwr/egsr07/183-194
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发表时间：
2007-06
期刊：
影响因子：
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通讯作者：
Wan-Chun Ma;Tim Hawkins;Pieter Peers;Charles-Félix Chabert;Malte Weiss;P. Debevec
中科院分区：
文献类型：
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作者：
Wan-Chun Ma;Tim Hawkins;Pieter Peers;Charles-Félix Chabert;Malte Weiss;P. Debevec
我们使用四种球面渐变照明模式，从物体的漫反射或镜面反射来估计物体的表面法线贴图。与传统的光度学立体不同，球形图案允许从任意数量的视点同时估计法线。我们提出了两种偏振照明技术，允许独立测量对象的漫反射和镜面法线贴图。对于散射材料，我们表明镜面法线贴图产生了细节表面形状的最佳记录，而漫反射法线由于次表面散射而偏离真实表面法线，并且这种影响依赖于波长。我们展示了这种捕获技术的几个应用。首先，我们使用时分多路照明从多个观察位置同时捕捉面部表现的法线贴图。其次，我们证明了基于镜面反射分量的高分辨率法线贴图可以与结构光3D扫描一起使用，使用现成的数字静止相机快速获得高分辨率的面部表面几何图形。最后，我们提出了一个实时着色模型，该模型使用镜面反射和漫反射颜色通道的独立估计法线贴图来再现一些感知上重要的次表面散射效果。
We estimate surface normal maps of an object from either its diffuse or specular reflectance using four spherical gradient illumination patterns. In contrast to traditional photometric stereo, the spherical patterns allow normals to be estimated simultaneously from any number of viewpoints. We present two polarized lighting techniques that allow the diffuse and specular normal maps of an object to be measured independently. For scattering materials, we show that the specular normal maps yield the best record of detailed surface shape while the diffuse normals deviate from the true surface normal due to subsurface scattering, and that this effect is dependent on wavelength. We show several applications of this acquisition technique. First, we capture normal maps of a facial performance simultaneously from several viewing positions using time-multiplexed illumination. Second, we show that highresolution normal maps based on the specular component can be used with structured light 3D scanning to quickly acquire high-resolution facial surface geometry using off-the-shelf digital still cameras. Finally, we present a realtime shading model that uses independently estimated normal maps for the specular and diffuse color channels to reproduce some of the perceptually important effects of subsurface scattering.