Calibration of Housing Parameters for Underwater Stereo-Camera Rigs

When using perspective cameras underwater, the underwater housing with its glass interface between water and air causes the light rays to change their direction due to refraction. In applications where geometrical properties of images are exploited without explicitly modeling refraction, i.e. when using the perspective pinhole camera model, this leads to a systematical error. This error is depending on the housing configuration like distance between camera and glass interface and angle between glass interface normal and optical axis. In this paper, we analyze the calibration of those parameters using a camera model explicitly considering refraction. The goal is to determine those parameters without the need of handling a calibration target underwater, which is cumbersome, if not impossible.