Light invariant photometric stereo

An imaging setup that enables unsynchronized photometric stereo (PS) for Lambertian objects based on modulated light sources is presented. Knowing the specific frequency of the modulated light source allows to filter out any other light in the scene. This creates an image that depends only on the particular light source while ignoring the ambient light. Moreover, if the scene is illuminated by multiple modulated sources with different frequencies, repeating this process for every frequency will produce a sequence of images with the corresponding illumination. This sequence is then used as an input to the PS algorithm for 3D reconstruction. The proposed approach, named Light Invariant Photometric Stereo (LIPS), was verified on both synthetic and real-world data. LIPS eliminates the need for synchronization between the sources and the camera and significantly outperformed the classical PS method in an illuminated environment.