GReTA - a novel Global and Recursive Tracking Algorithm in three dimensions

TL;DR

GReTA is a robust 3D multi-target tracking algorithm that effectively handles severe occlusions using a global optimization approach, scalable divide-and-conquer strategy, and validated on diverse datasets.

Contribution

Introduces GReTA, a novel 3D tracking method that addresses occlusion challenges with a global optimization and divide-and-conquer approach, enabling high-quality tracking of hundreds of targets.

Findings

High accuracy in tracking multiple targets with severe occlusions

Effective on synthetic, biological, and benchmark datasets

Scalable to hundreds of targets in complex scenarios

Abstract

Tracking multiple moving targets allows quantitative measure of the dynamic behavior in systems as diverse as animal groups in biology, turbulence in fluid dynamics and crowd and traffic control. In three dimensions, tracking several targets becomes increasingly hard since optical occlusions are very likely, i.e. two featureless targets frequently overlap for several frames. Occlusions are particularly frequent in biological groups such as bird flocks, fish schools, and insect swarms, a fact that has severely limited collective animal behavior field studies in the past. This paper presents a 3D tracking method that is robust in the case of severe occlusions. To ensure robustness, we adopt a global optimization approach that works on all objects and frames at once. To achieve practicality and scalability, we employ a divide and conquer formulation, thanks to which the computational complexity of the problem is reduced by orders of magnitude. We tested our algorithm with synthetic data, with experimental data of bird flocks and insect swarms and with public benchmark datasets, and show that our system yields high quality trajectories for hundreds of moving targets with severe overlap. The results obtained on very heterogeneous data show the potential applicability of our method to the most diverse experimental situations.