Birefractive stereo imaging for single-shot depth acquisition

Abstract

We propose a novel birefractive depth acquisition method, which allows for single-shot depth imaging by just placing a birefringent material in front of the lens. While most transmissive materials present a single refractive index per wavelength, birefringent crystals like calcite posses two, resulting in a double refraction effect. We develop an imaging model that leverages this phenomenon and the information contained in the ordinary and the extraordinary refracted rays, providing an effective formulation of the geometric relationship between scene depth and double refraction. To handle the inherent ambiguity of having two sources of information overlapped in a single image, we define and combine two different cost volume functions. We additionally present a novel calibration technique for birefringence, carefully analyze and validate our model, and demonstrate the usefulness of our approach with several image-editing applications.