A 3D group object tracking method for honeybees in open spaces

In this paper, we present a 3D group object stable tracking method based on binocular vision, called STBV, which is applied to the observation of flying honeybees in open spaces. Unlike typical multiple objects, group objects exhibit unique characteristics, such as a high population density, similar visual appearance among individuals, and similar motion patterns among individuals. Bees in free flight, as a representative example of such group objects, additionally possess traits such as small physical dimensions, agile motion, and variable target numbers, making effective tracking a formidable challenge. In this case, conventional trajectory construction strategies cause frequent ID switches, further causing instability of reconstructed 3D trajectories. To address this issue, the temporal stability of target instantaneous features and mutual support from binocular observation information are both used to improve the trajectory construction strategy in our paper. To verify our method, a 2D honeybee tracking dataset, HoneyBee2D, and a 3D honeybee tracking dataset, HoneyBee3D, were collected and annotated. The experimental results validate that the new strategy efficiently reduces the number of ID switches in 2D trajectories and consequently promotes the stability of reconstructed 3D trajectories. Furthermore, our reconstructed 3D flight trajectories of bees were used to analyze their motion and behavioral characteristics in a natural state and in an external disturbance state.