Stripping away sky reflectance, waves and turbulence for benthic mapping: Imaging the seafloor not the surface
Date
2008
Authors
Hart, D.
Lewis, M.
Ostendorf, B.
Editors
Advisors
Journal Title
Journal ISSN
Volume Title
Type:
Conference paper
Citation
Australasian Remote Sensing and Photogrammetry Conference Proceedings, 29 Sep -3 Oct 2008: 8 p
Statement of Responsibility
Conference Name
Australasian Remote Sensing and Photogrammetry Conference (14th : 2008 : Darwin, Australia)
Abstract
This paper presents the results of an airborne experiment using horizontal and vertical polarising filters on a pair of co-mounted 12.8 megapixel Canon 5D digital cameras. These cameras were mounted in the underside camera port of a light aircraft, both cameras inclined at 30 degrees off-nadir. One camera had the polarisation filter oriented vertically and the other oriented horizontally. Forward-looking, overlapping, oblique aerial photography was captured over known seagrass meadows off the Adelaide metropolitan coastline, plus inland urban water bodies. The portrait oriented field of view allowed a progression on the image from near-nadir to beyond the critical Brewster angle of 53 degrees. Results show the removal of sky reflectance, turbulence and wave action on the vertically-oriented filter imagery compared to the horizontally-oriented filter imagery in both clear and turbid waters. For clear waters the removal of sky reflectance, waves and surface turbulence allowed visualisation of the seafloor suitable for benthic mapping in areas of seagrass. However in turbid water the removal of surface effects still did not allow the seafloor to be visualised due to multiple scatter in the body of the water. This method therefore also has application in differentiating clear and turbid waters on oblique photography.