Photometric Stereo with Area Lights for Lambertian Surfaces

Abstract

This paper presents a photometric stereo technique that uses area lights for normal recovery and 3D geometry reconstruction of mid-sized objects. The object is illuminated in succession by several off-the-shelf LED area lights and images are captured by at least two DSLR cameras. Compared to point light sources, area lights have the advantage of producing high illuminance, resulting in low image noise and fast shutter speed, which is important if the captured object is not completely static during the acquisition of the images, e.g., when capturing a human face. Area lights are standard photo equipment which makes them cheaper, easier to obtain, and install than specialized many-lights hardware. The normal map of the object is recovered by our photometric stereo approach that uses ray tracing techniques to simulate the light transport in the scene. Furthermore, our approach takes the effects of occlusion and interreflections into account. The normal map is iteratively optimized which in turn is utilized to update the depth information of the object. Our synthetic and real-world experiments show that area lights are applicable for photometric stereo at the cost of an increased computational effort.