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Open AccessArticle

Mapping Coral Reef Benthos, Substrates, and Bathymetry, Using Compact Airborne Spectrographic Imager (CASI) Data

1
Centre for Spatial Environmental Research, School of Geography, Planning and Environmental Management, University of Queensland, St Lucia, QLD 4072, Australia
2
Research Institute for the Environment and Livelihoods, Charles Darwin University, Casuarina Campus, Darwin, NT 0810, Australia
3
CSIRO Earth Observation & Informatics Future Science Platform, Canberra, ACT 2601, Australia
*
Author to whom correspondence should be addressed.
Remote Sens. 2014, 6(7), 6423-6445; https://doi.org/10.3390/rs6076423
Received: 8 May 2014 / Revised: 4 July 2014 / Accepted: 8 July 2014 / Published: 14 July 2014
This study used a reef-up approach to map coral reef benthos, substrates and bathymetry, with high spatial resolution hyperspectral image data. It investigated a physics-based inversion method for mapping coral reef benthos and substrates using readily available software: Hydrolight and ENVI. Compact Airborne Spectrographic Imager (CASI) data were acquired over Heron Reef in July 2002. The spectral reflectance of coral reef benthos and substrate types were measured in-situ, and using the HydroLight 4.2 radiative transfer model a spectral reflectance library of subsurface reflectance was simulated using water column depths from 0.5–10.0 m at 0.5 m intervals. Using the Spectral Angle Mapper algorithm, sediment, benthic micro-algae, algal turf, crustose coralline algae, macro-algae, and live coral were mapped with an overall accuracy of 65% to a depth of around 8.0 m; in waters deeper than 8.0 m the match between the classified image and field validation data was poor. Qualitative validation of the maps showed accurate mapping of areas dominated by sediment, benthic micro-algae, algal turf, live coral, and macro-algae. A bathymetric map was produced for water column depths 0.5–10.0 m, at 0.5 m intervals, and showed high correspondence with in-situ sonar data (R2 value of 0.93). View Full-Text
Keywords: coral reef; remote sensing; hyperspectral; CASI; spectral angle mapper coral reef; remote sensing; hyperspectral; CASI; spectral angle mapper
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Leiper, I.A.; Phinn, S.R.; Roelfsema, C.M.; Joyce, K.E.; Dekker, A.G. Mapping Coral Reef Benthos, Substrates, and Bathymetry, Using Compact Airborne Spectrographic Imager (CASI) Data. Remote Sens. 2014, 6, 6423-6445.

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