Underwater stereo SLAM with refraction correction

Abstract

This work presents a method for underwater stereo localization and mapping for detailed inspection tasks. The method generates dense, geometrically accurate reconstructions of underwater environments by compensating for image distortions due to refraction. A refractive model of the camera and enclosure is calculated offline using calibration images and produces non-linear epipolar curves for use in stereo matching. An efficient block matching algorithm traverses the precalculated epipolar curves to find pixel correspondences and depths are calculated using pixel ray tracing. Finally the depth maps are used to perform dense simultaneous localization and mapping to generate a 3D model of the environment. The localization and mapping algorithm incorporates refraction corrected ray tracing to improve map quality. The method is shown to improve overall depth map quality over existing methods and to generate high quality 3-D reconstructions.