Item: Using Time Lapse Photography to Document Terrain Preferences of Backcountry Skiers
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Title: Using Time Lapse Photography to Document Terrain Preferences of Backcountry Skiers
Proceedings: International Snow Science Workshop Proceedings 2018, Innsbruck, Austria
Authors:
- Diana Saly [ Snow and Avalanche Laboratory, Department of Earth Sciences Montana State University, Bozeman, MT, USA ]
- Jordy Hendrikx [ Snow and Avalanche Laboratory, Department of Earth Sciences Montana State University, Bozeman, MT, USA ]
- Karl Birkeland [ USDA Forest Service National Avalanche Center, Bozeman, MT, USA ]
- Stuart Challender [ Snow and Avalanche Laboratory, Department of Earth Sciences Montana State University, Bozeman, MT, USA ]
- Jerry Johnson [ Snow and Avalanche Laboratory, Department of Earth Sciences Montana State University, Bozeman, MT, USA ]
Date: 2018-10-07
Abstract: This paper presents a method developed to capture the terrain metrics of all visible skiers on an avalanche-prone backcountry slope. A remote time-lapse camera focused on Saddle Peak (a high skier-use backcountry slope in the Bridger Mountain Range of southwest Montana, USA) captured 31,960 photos of 525 skiers descending in ten-second increments on 13 unique days. Skier locations (7,499 location-points) were digitized from the photos, then transformed onto a geo-referenced digital elevation model (DEM) such that terrain metrics could be applied to each of the 7,499 skier locations. Analysis of terrain metrics for each skier point compared slope, profile curvature (downslope), and plan curvature (cross-slope) over days with three different forecasted avalanche hazards (Con, Mod, Low). Terrain metrics on Considerable avalanche hazard days differed significantly from Moderate or Low avalanche hazard days (p-value < 0.001). Skier location-points transformed from the oblique photos to a geographic coordinate system had an observed horizontal spatial accuracy of 49-m with a 95% confidence interval. By capturing all visible skiers on a slope anonymously, the data provides a large and diverse data set of the terrain preferences of backcountry skiers under varying conditions. Time lapse photography presents a simple and inexpensive tool for effectively monitoring skiers in avalanche terrain. Skier images can be useful in determining high-use areas of skier traffic, crowding or congestion issues, documenting avalanches, and recording avalanche control operations. It has also proven to be useful with assisting avalanche emergencies by providing visual survey of the avalanche path including determining number of people (if any) involved, identifying triggers and last seen points, and assessing residual risk to responders.
Object ID: ISSW2018_P04.5.pdf
Language of Article: English
Presenter(s):
Keywords: terrain, avalanche, time-lapse photography.
Page Number(s): 369-372
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