PT - JOURNAL ARTICLE AU - Francisco Romero-Ferrero AU - Mattia G. Bergomi AU - Robert Hinz AU - Francisco J. H. Heras AU - Gonzalo G. de Polavieja TI - idtracker.ai: Tracking all individuals in large collectives of unmarked animals AID - 10.1101/280735 DP - 2018 Jan 01 TA - bioRxiv PG - 280735 4099 - http://biorxiv.org/content/early/2018/03/14/280735.short 4100 - http://biorxiv.org/content/early/2018/03/14/280735.full AB - Our understanding of collective animal behavior is limited by our ability to track each of the individuals. We describe an algorithm and software, idtracker.ai, that extracts from video all trajectories with correct identities at a high accuracy for collectives of up to 100 individuals. It uses two deep networks, one detecting when animals touch or cross and an-other one for animal identification, trained adaptively to conditions and difficulty of the video.