Oregon Sea Grant

With this study reserachers present a three program analysis suite that measures baleen whales and compensates for lens distortion and corrects scaling error to produce 11 morphometric attributes from sUAS imagery. The program is freely available and is expected to improve processing efficiency and analytical continuity.

Small, unmanned aircraft systems (sUASs) are fostering novel approaches to marine mammal research, including baleen whale photogrammetry which provide new observational perspectives. Researchers collected vertical images of 89 gray and 6 blue whales using low cost sUASs to examine the accuracy of image based morphometry. Moreover, measurements from 192 images of a 1 m calibration object were used to examine four different scaling correction models. Results indicate that a linear mixed model including an error term for flight and date contained 0.17 m less error and 0.25 m less bias than no correction. Reserachers used the propagation uncertainty law to examine error contributions from scaling and image measurement (digitization) to determine that digitization accounted for 97% of total variance. Additionally, they present a new whale, body-size metric termed Body Area Index (BAI). BAI is scale invariant and is independent of body length(R2 = 0.11), enabling comparisons of body size within and among
populations, and over time.

Authors: Jonathan D. Burnett; Leila Lemos; Dawn Barlow; Michael G. Wing; Todd Chandler; Leigh G. Torres