纹理物体表面反射参数的恢复

物体表面反射参数的恢复是新兴的逆向绘制技术的核心问题，提出一种恢复物体表面BRDF模型参数的方法，假定物体表面的BRDF模型可以近似分解为漫射纹理和整体不变的镜面反射分量，则每一点的反射参数可以用Phong模型来近似计算，首先选取物体表面的一片区域，利用该区域在不同视点光照条件下采样的几幅图像，计算得到该区域的平均镜面反射分量，作为整个物体表面的镜面反射分量，然后据此从物体表面各点的采样中分离出漫射分量，计算各点的漫反射参数，得到近似的BRDF模型，实验数据表明算法是有效的。

REFLECTANCE MODELING FOR A TEXTURED OBJECT FROM PHOTOGRAPHS

Inverse rendering is a budding technique. Its goal is to obtain information of illumination, reflectance properties and textures of real objects. Reflectance recovery is a key problem in inverse rendering. An approach to recovering the reflectance properties of a textured object from photographs is introduced. Assuming that the object has a constant specular reflectance property over its surface, the BRDF can be approximated by a constant specular component and a varying diffuse component. Thus the problem becomes much easier to solve. First, a patch on the surface is selected, several pictures are taken under different viewing and lighting conditions for it, and the average specular reflectance parameter value of this patch is recovered and regarded as the value over the whole surface. Then the specular component and the diffuse component of each sample are separated, and with the separated diffuse component, the diffuse reflectance parameters for each point on the surface can be recovered. The test results show that the method is effective for textured objects with constant specular reflectance properties.