Lookup NU author(s): Professor Stuart Barr,
Professor Jon Mills
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Photogrammetric processing of archival stereo imagery offers the opportunity to reconstruct glacier volume changes for regions where no such data exist, and to better constrain the contribution to sea-level rise from small glaciers and ice caps. The ability to derive digital elevation model (DEM) measurements of glacier volume from photogrammetry relies on good-quality, well-distributed ground reference data, which may be difficult to acquire. This study shows that ground-control points (GCPs) can be identified and extracted from point-cloud airborne lidar data and used to control photogrammetric glacier models. The technique is applied to midtre Lovenbreen, a small valley glacier in northwest Svalbard. We show that the amount of ground control measured and the elevation accuracy of GCP coordinates (based on known and theoretical error considerations) has a significant effect on photogrammetric model statistics, DEM accuracy and the subsequent geodetic measurement of glacier volume change. Models controlled with fewer than 20 lidar control points or GCPs from sub-optimal areas within the swath footprint overestimated volume change by 14-53% over a 2 year period. DEMs derived from models utilizing 20-25 or more GCPs, however, gave volume change estimates within similar to 4% of those from repeat lidar data (-0.51 m a(-1) between 2003 and 2005). Our results have important implications for the measurement of glacier volume change from archival stereo-imagery sources.
Author(s): Barrand NE, Murray T, James TD, Barr SL, Mills JP
Publication type: Article
Publication status: Published
Journal: Journal of Glaciology
ISSN (print): 0022-1430
ISSN (electronic): 1727-5652
Publisher: International Glaciological Society
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