Polar-Photometric Stereo Under Natural Illumination

We present a 3D shape reconstruction method that leverages both photometric and polarimetric cues. Unlike many active methods that require controlled lighting condition, our method can be used under unknown and uncontrolled natural illumination (both indoor and outdoor). We use two circularly polarized spotlights to boost the polarization cues corrupted by the environment lighting, as well as to provide photometric cues. We solve surface normals with two polarization images by combining the polarimetric and photometric constraints. To mitigate the effect of uncontrolled environment light in photometric constraints, we es-timate a lighting proxy map and iteratively refine the normal and lighting estimation. We perform experiments under various natural illumination conditions and compare our results with state-of-the-arts photometric stereo and shape from polarization methods. Our method achieves good accuracy and can be used in flexible environment.