USING HIGH-RESOLUTION PHOTOMOSAICKING TECHNIQUES TO VALIDATE BENTHIC COVER DATA FROM REMOTE SENSING TECHNOLOGIES
Remote sensing has the ability to acquire uniform data at high spatial resolution across large areas. However, most commonly used reef survey techniques are insufficient for relating precise, detailed ecosystem statistics to airborne or spaceborne measurements, and thus are not ideal for validation of remote sensing products. We present an in situ methodology that can produce geolocated photomosaics of the seafloor community at the scale of a remotely sensed pixel. As part of the COral Reef Airborne Laboratory (CORAL) mission, underwater photographs were collected at 30–50 sites each across Kaneohe Bay, Oahu; Lizard Island, Australia; and Heron Island, Australia. At each site, we collected 400–2000 digital photographs across a minimum area of 10 m x 10 m of the seafloor (CORAL pixels are ~8 m x 8 m). Photographs were processed using Agisoft PhotoScan Pro to generate a single photomosaic at each site. Each photomosaic was then analyzed using standard point-count methods to provide proportional benthic cover of reef functional types (primarily coral, algae and sediment). The high-resolution photomosaics provided detailed and accurate benthic composition data on a spatial scale directly comparable to the remotely sensed pixels. Our work demonstrates that this methodology is a comparatively low-cost, efficient platform for rapidly surveying large areas of reef. We envision this methodology as a vital validation tool for future airborne and satellite missions, which can ultimately provide a comprehensive assessment of global reef condition in relation to biogeophysical forcings.
Peltier, S. A., Bermuda Institute of Ocean Sciences, Bermuda, firstname.lastname@example.org
Hochberg, E. J., Bermuda Institute of Ocean Sciences, Bermuda, email@example.com
Dollar, S. J., University of Hawaii, USA, firstname.lastname@example.org
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