Terrain changes from images acquired on opportunistic flights by SfM photogrammetry
Acquiring data to analyse change in topography is often a costly endeavour requiring either extensive, potentially risky, fieldwork and/or expensive equipment or commercial data. Bringing the cost down while keeping the precision and accuracy has been a focus in geoscience in recent years. Structure...
Main Authors: | , , , , |
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Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2017-03-01
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Series: | The Cryosphere |
Online Access: | http://www.the-cryosphere.net/11/827/2017/tc-11-827-2017.pdf |
Summary: | Acquiring data to analyse change in topography is often a costly endeavour
requiring either extensive, potentially risky, fieldwork and/or expensive
equipment or commercial data. Bringing the cost down while keeping the
precision and accuracy has been a focus in geoscience in recent years.
Structure from motion (SfM) photogrammetric techniques are emerging as
powerful tools for surveying, with modern algorithm and large computing power
allowing for the production of accurate and detailed data from low-cost,
informal surveys. The high spatial and temporal resolution permits the
monitoring of geomorphological features undergoing relatively rapid change,
such as glaciers, moraines, or landslides. We present a method that takes
advantage of light-transport flights conducting other missions to
opportunistically collect imagery for geomorphological analysis. We test and
validate an approach in which we attach a consumer-grade camera and a simple
code-based Global Navigation Satellite System (GNSS) receiver to a helicopter
to collect data when the flight path covers an area of interest. Our method
is based and builds upon Welty et al. (2013),
showing the ability to link GNSS data to images without a complex physical or
electronic link, even with imprecise camera clocks and irregular time lapses.
As a proof of concept, we conducted two test surveys, in September 2014 and
2015, over the glacier Midtre Lovénbreen and its forefield, in
northwestern Svalbard. We were able to derive elevation change estimates
comparable to in situ mass balance stake measurements. The accuracy and
precision of our DEMs allow detection and analysis of a number of processes
in the proglacial area, including the presence of thermokarst and the
evolution of water channels. |
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ISSN: | 1994-0416 1994-0424 |