Dear colleagues,
My co-authors and I are happy to announce the publication of the following paper in Remote Sensing in Ecology and Conservation:
Bagchi, C., Medina, J., Irschick, D.J., Maji, S. and Christiansen, F. (2025), Automated extraction of right whale morphometric data from drone aerial photographs. Remote Sens Ecol Conserv.
https://doi.org/10.1002/rse2.70001
Abstract
Aerial photogrammetry is a popular non-invasive tool to measure the size, body morphometrics and body condition of wild animals. While the method can generate large datasets quickly, the lack of efficient processing tools can create bottlenecks that delay management
actions. We developed a machine learning algorithm to automatically measure body morphometrics (body length and widths) of southern right whales (Eubalaena australis, SRWs) from aerial photographs (n = 8,958) collected by unmanned aerial vehicles in
Australia. Our approach utilizes two Mask R-CNN detection models to: (i) generate masks for each whale and (ii) estimate points along the whale’s axis. We annotated a dataset of 468 images containing 638 whales to train our models. To evaluate the accuracy
of our machine learning approach, we compared the model-generated body morphometrics to manual measurements. The influence of picture quality (whale posture and water clarity) was also assessed. The model-generated body length estimates were slightly negatively
biased (median error of -1.3%), whereas the body volume estimates had a small (median error of 6.5%) positive bias. After correcting both biases, the resulting model-generated body length and volume estimates had mean absolute errors of 0.85% (SD = 0.75) and
6.88% (SD = 6.57), respectively. The magnitude of the errors decreased as picture quality increased. When using the model-generated data to quantify intra-seasonal changes in body condition of SRW females, we obtained a similar slope parameter (-0.001843,
SE = 0.000095) as derived from manual measurements (-0.001565, SE = 0.000079). This indicates that our approach was able to accurately capture temporal trends in body condition at a population level.
The paper is Open Access and can be accessed from the following link:
Best regards,
Fredrik Christiansen
Senior Researcher
Marine Mammal Research
Department of Ecoscience
Aarhus University, Denmark