Lightfield Analysis of Curved Mirrors: Reflect Your Perspective, Widen Your View

Mirrors have been used to enable wide field-of-view (FOV) catadioptric imaging. The mapping between the incoming and reflected light rays depends non-linearly on the mirror shape and has been well-studied using caustics. We analyze this mapping using the two-plane lightfield parameterization, which provides valuable insight into the geometric structure of reflected rays. Using this analysis, we study the problem of generating a single-viewpoint virtual perspective image for catadioptric systems, which is unachievable for several common configurations. Instead of minimizing distortions appearing in a single image, we propose to capture all the rays required to generate a virtual perspective by capturing a lightfield. We consider rotationally symmetric mirrors and show that a traditional planar lightfield results in significant aliasing artifacts. We propose axial lightfield, captured by moving the camera along the mirror rotational axis for efficient sampling and to remove aliasing artifacts. This allow us to computationally generate wide FOV virtual perspectives using a wider class of mirrors than before, without using scene priors or depth estimation. We analyze the relationship between the axial lightfield parameters and FOV/resolution of the resulting virtual perspective. Real results using a sphere demonstrate generating 140◦ FOV virtual perspective using multiple 30◦ FOV images.