Investigators: Susan Piacenza, Joseph Piacenza (OSU), John Faller (CSU Fullerton), Nathan Robinson (Oceanografic Valencia - Spain), Tabitha Siegfried
The recent commercialization of unoccupied aerial vehicles (UAVs) has facilitated their incorporation into a variety of ecological studies. While UAVs are able to provide accurate visual data from an aerial perspective, these devices remain limited in their ability to accurately measure the size of smaller organisms (i.e.< 2 m). We have developed and tested a stereo-video camera (SVC) system that was mounted onto a commercially-available UAV. We used the SVC-UAV to conduct remote body-size measurements for two marine species: the green sea turtle (Chelonia mydas) and the nurse shark (Ginglymostoma cirratum). When comparing SVC measurements to those taken by hand, the SVC-UAV had a mean absolute error (MAE) of 4.44 cm (n=6) for green sea turtles and 7.16 cm (n=1) for the nurse shark. Using a linear model, we estimated the slope of the SVC versus hand measurements for green sea turtles to be 1.085 (±0.099 SE). Using model selection, based on a global model predicting MAE from animal distance to the SVC and body size, the top ranked model was the intercept-only model. This indicates that neither animal distance nor body size strongly influenced measurement error. Incorporating SVC systems into UAVs can allow for relatively accurate measurements of surface-dwelling marine species. To our knowledge, there is no other stand-alone SVC for UAVs available that offers similar accuracy and utility.
The recent commercialization of unoccupied aerial vehicles (UAVs) has facilitated their incorporation into a variety of ecological studies. While UAVs are able to provide accurate visual data from an aerial perspective, these devices remain limited in their ability to accurately measure the size of smaller organisms (i.e.< 2 m). We have developed and tested a stereo-video camera (SVC) system that was mounted onto a commercially-available UAV. We used the SVC-UAV to conduct remote body-size measurements for two marine species: the green sea turtle (Chelonia mydas) and the nurse shark (Ginglymostoma cirratum). When comparing SVC measurements to those taken by hand, the SVC-UAV had a mean absolute error (MAE) of 4.44 cm (n=6) for green sea turtles and 7.16 cm (n=1) for the nurse shark. Using a linear model, we estimated the slope of the SVC versus hand measurements for green sea turtles to be 1.085 (±0.099 SE). Using model selection, based on a global model predicting MAE from animal distance to the SVC and body size, the top ranked model was the intercept-only model. This indicates that neither animal distance nor body size strongly influenced measurement error. Incorporating SVC systems into UAVs can allow for relatively accurate measurements of surface-dwelling marine species. To our knowledge, there is no other stand-alone SVC for UAVs available that offers similar accuracy and utility.
All sea turtle species in US waters are on the US Endangered Species List. Since the in-water research conducted by the Piacenza QMCE Lab on endangered species is remote and encounters with animals are less than 5 minutes, we do not require scientific research permits from federal or state agencies. We have consulted with the relevant state and federal agencies to ascertain if scientific research permits are required. If you encounter sea turtles or other endangered marine species in the wild, do not approach them or follow them, as this could result in unintentional harm. Please see the NOAA webpage Marine Wildlife Viewing Guidelines for best practices. Research conducted in Eleuthera was permitted by the Bahamian Department of Marine Resources (permit MA\&MR/FIS/9).