New techniques to measure cliff change from historical oblique aerial photographs and structure-from-motion photogrammetry

Journal of Coastal Research
Olympic National Park; California Coastal Records Project
By: , and 

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Abstract

Oblique aerial photograph surveys are commonly used to document coastal landscapes. Here it is shown that adequate overlap may exist in these photographic records to develop topographic models with Structure-from-Motion (SfM) photogrammetric techniques. Using photographs of Fort Funston, California, from the California Coastal Records Project, imagery were combined with ground control points in a four-dimensional analysis that produced topographic point clouds of the study area’s cliffs for 5 years spanning 2002 to 2010. Uncertainty was assessed by comparing point clouds with airborne LIDAR data, and these uncertainties were related to the number and spatial distribution of ground control points used in the SfM analyses. With six or more ground control points, the root mean squared errors between the SfM and LIDAR data were less than 0.30 m (minimum 1⁄4 0.18 m), and the mean systematic error was less than 0.10 m. The SfM results had several benefits over traditional airborne LIDAR in that they included point coverage on vertical- to-overhanging sections of the cliff and resulted in 10–100 times greater point densities. Time series of the SfM results revealed topographic changes, including landslides, rock falls, and the erosion of landslide talus along the Fort Funston beach. Thus, it was concluded that SfM photogrammetric techniques with historical oblique photographs allow for the extraction of useful quantitative information for mapping coastal topography and measuring coastal change. The new techniques presented here are likely applicable to many photograph collections and problems in the earth sciences.

Additional publication details

Publication type Article
Publication Subtype Journal Article
Title New techniques to measure cliff change from historical oblique aerial photographs and structure-from-motion photogrammetry
Series title Journal of Coastal Research
DOI 10.2112/JCOASTRES-D-16-00095.1
Volume 33
Issue 1
Year Published 2017
Language English
Publisher BioOne, Coastal education and research foundation
Contributing office(s) Pacific Coastal and Marine Science Center
Description 17 p.
First page 39
Last page 55