Drone photogrammetry and KMeans point cloud filtering to create high resolution topographic and inundation models of coastal sediment archives

作者：Callow, J. N.^*; May, S. M.; Leopold, M.

来源：Earth Surface Processes and Landforms, 2018, 43(12): 2603-2615.

DOI：10.1002/esp.4419

• structure from motion (SfM)
• photogrammetry
• remotely piloted aircraft systems (RPAS)
• point cloud filtering
• KMeans
• coastal washover deposit
• digital elevation model (DEM)

Coastal areas are vulnerable to the impacts of tropical cyclones (TC), tsunamis and other water super-elevation events, but the frequency of these events is often poorly represented by conventional records. Coastal overwash deposits (including washover fans) can provide a longer-term archive of event frequency. Because of their low-gradient geomorphic form, washover fans require high accuracy (centimetre-resolution) topographic models to understand patterns of connectivity and dynamics that control archive formation. Using images collected by a remotely piloted aircraft system (RPAS, or drone') and Structure-from-Motion (SfM) photogrammetry techniques, we apply a novel point-cloud filtering technique based on KMeans classification of the R-G-B colour of each X-Y-Z point to remove vegetation and create a centimetre-resolution and accuracy bare-earth digital terrain model (DTM) of a washover fan in Exmouth Gulf (Western Australia). Using the RPAS-SfM orphophoto and DEM data, supported by ground-penetrating radar (GPR) and field stratigraphic analysis, we show how this approach can be applied to understand dynamics controlling low-gradient geomorphic landforms, using an example of a washover fan sedimentary archive in northwestern Australia created by extreme overwash events. Our approach reveals the likely role of backflooding and terrestrial runoff in creating backwater environment for sub-aqueous deposition and good sediment preservation and identifies key areas to target for detailed dating and stratigraphic analysis of a potentially decadal to sub-millennial resolution sediment archive of TC activity.

• 出版日期2018-9-30