Measuring coral reef terrain roughness using 'Structure-from-Motion' close-range photogrammetry

Leon, J. X., Roelfsema, Chris M., Saunders, Megan I. and Phinn, Stuart R. (2015) Measuring coral reef terrain roughness using 'Structure-from-Motion' close-range photogrammetry. Geomorphology, 242 21-28. doi:10.1016/j.geomorph.2015.01.030

Author Leon, J. X.
Roelfsema, Chris M.
Saunders, Megan I.
Phinn, Stuart R.
Title Measuring coral reef terrain roughness using 'Structure-from-Motion' close-range photogrammetry
Journal name Geomorphology   Check publisher's open access policy
ISSN 0169-555X
Publication date 2015-08-01
Year available 2015
Sub-type Article (original research)
DOI 10.1016/j.geomorph.2015.01.030
Open Access Status Not yet assessed
Volume 242
Start page 21
End page 28
Total pages 8
Place of publication Amsterdam, Netherlands
Publisher Elsevier
Language eng
Subject 1904 Earth-Surface Processes
Abstract Our understanding of Earth surface processes is rapidly advancing as new remote sensing technologies such as LiDAR and close-range digital photogrammetry become more accessible and affordable. A very-high spatial resolution digital terrain model (DTM) and orthophoto mosaic (mm scale) were produced using close-range digital photogrammetry based on ‘Structure-from-Motion’ (SfM) algorithms for a 250 m transect along a shallow coral reef flat on Heron Reef, Great Barrier Reef. The precise terrain data were used to characterise surface roughness, a critical factor affecting ecological and physical processes on the reef. Three roughness parameters, namely the root mean square height, tortuosity (or rugosity) and fractal dimension, were derived and compared in order to asses which one better characterises reef flat roughness. The typical relief across the shallow reef flat was 0.1 m with a maximum value of 0.42 m. Coral reef terrain roughness, as characterised by the three chosen parameters, generally increased towards the middle of the transect where live coral covers most of the reef flat and decreases towards the edges of the transect. The fractal dimension (values ranging from 2.2 to 2.59) best characterised reef roughness, as evidenced by a closer agreement with the distribution of known coral benthic substrates. This is the first study quantifying scale-independent roughness of a coral reef at benthic and biotope/patch levels (cm-m). The readily available and cost-effective methods presented are highly appropriate for data collection, processing and analysis to generate very-high spatial resolution DTMs and orthophoto mosaics of shallow and energetic coral reefs.
Keyword Structure-from-motion (SfM)
Agisoft photoscan
Fractal dimension
Coral reef
Heron Reef
Remote sensing
Close range photography
Roughness measurements
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID FS100100024
Institutional Status UQ

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Created: Tue, 17 Mar 2015, 02:12:35 EST by Mr Chris Roelfsema on behalf of School of Geography, Planning & Env Management