"Photozoometer": A new photogrammetric system for obtaining morphometric measurements of elusive animals

This work presents and evaluates a new methodology for the measurement of animal morphometrics. With this method, measurements are obtained using 3D image analysis, or photogrammetry, from pairs of pictures taken with a portable instrument incorporating two synchronized cameras. The method facilitates measurements of animals in their natural environment without the need to immobilize or anesthetize the animals or to place any external measuring device in the environment. The proposed methodology is useful if traditional measurements of large animals are not possible or difficult, costly or dangerous, as is the case with wild animals such as elephants, rhinoceroses, hippopotamuses or dangerous or elusive species, such as fighting bulls and ostriches, which would be difficult to measure manually. To evaluate the methodology, zoometric measurements on cows were performed using both the proposed method and traditional methods. In general, the precision obtained by the proposed methodology was greater than or equal to that obtained with conventional instruments. There were no biases or systematic deviations greater than 1 cm and the photogrammetric measurements generally showed an accuracy within 0.5 cm.