Inexpensive Aerial Photogrammetry for Studies of Whales and Large Marine Animals
By S. Dawson, M. Hamish Bowman, E. Leunissen, P. Sirguey. Frontiers in Marine Science, 2017
97 citations recorded by the source corpus.
We describe a simple system enabling accurate measurement of swimming marine mammals and other large vertebrates from low-altitude single-frame photogrammetry via inexpensive modifications to a “prosumer” unmanned aerial vehicle (UAV) equipped with gimballed micro4/3 camera and 25 mm lens. Image scale is established via an independently powered LIDAR/GPS data-logging system recording altitude and GPS location at 1 Hz. Photogrammetric calibration of the camera and lens allowed distortion parameters to be rigorously accounted for during image analysis, via a custom-programmed Graphical User Interface running in MATLAB. The datalogger, camera calibration methods and measurement software are adaptable to a wide range of UAV platforms. Mean LIDAR accuracy, measured from 10 bridges 9-39 m above water, was 99.9%. We conducted 136 flights in New Zealand’s subantarctic Auckland Islands to measure southern right whales. Mean lengths of 10 individual whales, each photographed between 7 to 15 times, had CVs (SD/mean) ranging from 0.5-1.8 % (mean = 1.2 %). Repeated measurements of a floating reference target showed a mean error of c.1 %. Our system is relatively inexpensive, easily put together, produces accurate, repeatable measurements from single vertical images, and hence is applicable to a wide range of ecological questions in marine and terrestrial habitats.
Subfields: Aerospace Engineering, Environmental Engineering, Instrumentation
View Paper: https://www.semanticscholar.org/paper/ccde94e35ecbc9a5ccc2b86e5423646bbe151861
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In Aerospace Engineering
Citations in the corpus
- Estimating morphometric attributes of baleen whales with photogrammetry from small UASs: A case study with blue and gray whales (2018, background): “2015) or laser altimeters (Dawson et al. 2017) would reduce the dependency on calibration”
- Population comparison of right whale body condition reveals poor state of the North Atlantic right whale (2020, methodology): “2A), using a custom written graphical user interface (GUI) in MATLAB (Dawson et al. 2017).”
- Maternal body size and condition determine calf growth rates in southern right whales (2018, methodology): “Additional error estimates inherent to the camera and range finder system can be found in Dawson et al. (2017).”