Using UAV acquired photography and structure from motion techniques for studying glacier landforms: application to the glacial flutes at Isfallsglaciären

Abstract

This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.ABSTRACT: Glacier and ice sheet retreat exposes freshly deglaciated terrain which often contains small-scale fragile geomorphological features which could provide insight into subglacial or submarginal processes. Subaerial exposure results in potentially rapid landscape modification or even disappearance of the minor-relief landforms as wind, weather, water and vegetation impact on the newly exposed surface. Ongoing retreat of many ice masses means there is a growing opportunity to obtain high resolution geospatial data from glacier forelands to aid in the understanding of recent subglacial and submarginal processes. Here we used an unmanned aerial vehicle to capture close-range aerial photography of the foreland of Isfallsglaciären, a small polythermal glacier situated in Swedish Lapland. An orthophoto and a digital elevation model with~2 cm horizontal resolution were created from this photography using structure from motion software. These geospatial data was used to create a geomorphological map of the foreland, documenting moraines, fans, channels and flutes. The unprecedented resolution of the data enabled us to derive morphological metrics (length, width and relief) of the smallest flutes, which is not possible with other data products normally used for glacial landform metrics mapping. The map and flute metrics compare well with previous studies, highlighting the potential of this technique for rapidly documenting glacier foreland geomorphology at an unprecedented scale and resolution. The vast majority of flutes were found to have an associated stoss-side boulder, with the remainder having a likely explanation for boulder absence (burial or erosion). Furthermore, the size of this boulder was found to strongly correlate with the width and relief of the lee-side flute. This is consistent with the lee-side cavity infill model of flute formation. Whether this model is applicable to all flutes, or multiple mechanisms are required, awaits further study.

Evolution of high-Arctic glacial landforms during deglaciation

“…The SfM photogrammetry, with imagery typically obtained using small UAVs, is now commonplace for low-level aerial image acquisition (e.g., Tonkin et al, 2014;Rippin et al, 2015;Ely et al, 2017;Rossini et al, 2018). At Midtre Lovénbreen, a DJI S800 UAV was used to acquire aerial images on 20 July 2014.…”

Mapping Ground Instability in Areas of Geotechnical Infrastructure Using Satellite InSAR and Small UAV Surveying: A Case Study in Northern Ireland

“…We collected~140 close range aerial photographs (RGB/NIR) over the site and processed them to create a VHR ortho-photograph, a photogrammetry-derived dense point cloud and Digital Surface Model (DSM), using a Structure from Motion (SfM) computer vision approach (e.g., [16,17]) computed with AgiSoft PhotoScan Professional software (Educational Licensing; Agisoft LLC, St. Petersburg, Russia). The SfM approach is a multi-view stereo photogrammetric range imaging technique aimed to estimating three-dimensional (3D) structures from two-dimensional (2D) image sequences, usually acquired from a moving platform.…”

“…The SfM approach is a multi-view stereo photogrammetric range imaging technique aimed to estimating three-dimensional (3D) structures from two-dimensional (2D) image sequences, usually acquired from a moving platform. The approach does not require the use of expensive equipment, specialist expertise or extremely long processing times, and can allow the generation of 3D point clouds of vertical accuracy of a few centimeters (e.g., 5 cm [17]). Its emergence has therefore revolutionised 3D topographic surveying in physical geography [16].…”

High-Endurance UAV for Monitoring Calving Glaciers: Application to the Inglefield Bredning and Eqip Sermia, Greenland

“…• tidewater glacier ice flow and iceberg calving (Ryan et al, 2015;Jouvet et al, 2017;Chudley et al, 2019), • surface ice motion of mountain glaciers (Immerzeel et al, 2014;Gindraux et al, 2017), • glacial structures (Tonkin et al, 2016;Ely et al, 2017;Jones et al, 2018), • distribution of organic matter (Hodson et al, 2007;Stibal et al, 2017;Ryan et al, 2018), • spatial albedo patterns (Ryan et al, 2017Podgorny et al, 2018), • supraglacial drainage networks (Rippin et al, 2015), • ice surface melt (Bash et al, 2018).…”