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| Titel |
Ground-based structure from motion – multi view stereo (SFM-MVS) for upland soil erosion assessment. |
| VerfasserIn |
Gareth McShane, Mike James, John Quniton, Luke Farrow, Miriam Glendell, Lee Jones, Matthew Kirkham, David Morgan, Martin Evans, Karen Anderson, Murray Lark, Barry Rawlins, Jane Rickson, Timothy Quine, Pia Benaud, Richard Brazier |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250134810
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| Publikation (Nr.) |
 EGU/EGU2016-15576.pdf |
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| Zusammenfassung |
| In upland environments, quantifying soil loss through erosion processes at a high resolution
can be time consuming, costly and logistically difficult. In this pilot study ‘A cost
effective framework for monitoring soil erosion in England and Wales’, funded by the
UK Department for Environment, Food and Rural Affairs (Defra), we evaluate
the use of annually repeated ground-based photography surveys, processed using
structure-from-motion and multi-view stereo (SfM-MVS) 3-D reconstruction software
(Agisoft Photoscan). The aim is to enable efficient but detailed site-scale studies of
erosion forms in inaccessible UK upland environments, in order to quantify dynamic
processes, such as erosion and mass movement. The evaluation of the SfM-MVS
technique is particularly relevant in upland landscapes, where the remoteness and
inaccessibility of field sites may render some of the more established survey techniques
impractical.
We present results from 5 upland sites across the UK, acquired over a 2-year period.
Erosion features of varying width (3 m to 35 m) and length (20 m to 60 m), representing a
range of spatial scales (from 100 m2 to 1000 m2) were surveyed, in upland habitats
including bogs, peatland, upland grassland and moorland. For each feature, around 150
to 600 ground-based photographs were taken at oblique angles over a 10 to 20
minute period, using an uncalibrated Canon 600D SLR camera with a 28 mm lens
(focal length set to infinity). Camera settings varied based upon light conditions
(exposure 100-400 ISO, aperture F4.5 to F8, shutter speed 1/100 to 1/250 second). For
inter-survey comparisons, models were geo-referenced using 20 to 30 ground control
points (numbered black markers with a white target) placed around and within
the feature, with their co-ordinates measured by survey-grade differential GNSS
(Trimble R4). Volumetric estimates of soil loss were quantified using digital surface
models (DSMs) derived from the repeat survey data and subtracted from a modelled
pre-erosion surface (CloudCompare, Golden Software Surfer). We discuss the survey
performance achieved in terms of the time required and the precisions delivered,
and consider the practical application of SfM-MVS for long-term upland erosion
monitoring. |
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