Applying an Underwater Photography Technique to Nearshore Benthic Mapping: A Case Study in a Rocky Shore Environment

Abstract

Park, J.-Y.; Choi, J.Y.; and Jeong, E.Y., 2011. Applying an underwater photography technique to nearshore benthic mapping: A case study in a rocky shore environment. Journal of Coastal Research, SI 64 (Proceedings of the 11th International Coastal Symposium), 1764 - 1768. Szczecin, Poland, ISSN 0749-0208 Underwater photography technique was examined to apply digital raster images to nearshore benthic mapping of Dokdo, which is located farthest east from mainland of South Korea. Seabed underwater-photography survey was conducted for three survey lines at the nearshore zone. A total of 315 quasi-orthogonal color JPEG photographs of the seabed were taken sequentially along the survey lines by using an underwater digital camera system. The digital photographs were post-processed for adjusting the color, brightness and geometry of them using digital image processing software. The post-processed sequential photographs of each survey line were stitched as single image mosaics using a photo stitching software. The resulted image mosaics of Lines 1, 2 and D have 2191 x 48482 pixels (similar to 7.5 m x 168 m), 2717 x 43097 pixels (similar to 9.3 m x 148 m) and 4461 x 29720 pixels (similar to 15.2 x 80 m) in image size (image area), respectively. The image mosaics visually show transitional changes and boundaries of geological features thanks to their panoramic areal coverage. Their high image resolution also allows us to easily identify and classify the sedimentary characteristics and sand bedform features as well as certain benthic organisms. M a final process, we added georeference information to the image mosaics to make a 3-D photo surface bathymetry map and put them into a GIS system.