Stitching algorithm applied to camera array images for the visualization of Tubbataha reef grounding scars

Abstract

This paper presents a unique system specifically made to capture and create image mosaics of flat, wide, and shallow coral reefs at the Tubbataha Reefs Natural Park to assist in the rapid assessment of the reef scars caused by the grounding of the USS Guardian last January 17, 2013. This system is composed of an array of underwater cameras coupled with a GPS and depth logging device, and a mosaicking algorithm to stitch the images. The algorithm color corrects the images before creating panoramic strips of images across cameras. Linear regression is applied to the pixel shifts to smoothen values overlooked by the cross correlation function. The strips are then stitched across time to form image mosaics using modified fast image labeling. With an overlap of at least 30% between image frames, strips formed from an array of three cameras cover a distance more than twice the distance covered by a single camera.