Tracking Pedestrian Heads in Dense Crowd

TL;DR

This paper introduces CroHD, a large dataset for head tracking in dense crowds, along with a new head detector and a tracking method that outperforms existing approaches in identity preservation.

Contribution

The paper presents CroHD, a new dataset for head tracking in dense crowds, and introduces HeadHunter, a novel head detector combined with a particle filter for improved tracking.

Findings

HeadHunter outperforms existing detectors in crowded scenes.

The proposed tracker achieves superior identity preservation.

CroHD enables robust evaluation of dense crowd tracking algorithms.

Abstract

Tracking humans in crowded video sequences is an important constituent of visual scene understanding. Increasing crowd density challenges visibility of humans, limiting the scalability of existing pedestrian trackers to higher crowd densities. For that reason, we propose to revitalize head tracking with Crowd of Heads Dataset (CroHD), consisting of 9 sequences of 11,463 frames with over 2,276,838 heads and 5,230 tracks annotated in diverse scenes. For evaluation, we proposed a new metric, IDEucl, to measure an algorithm's efficacy in preserving a unique identity for the longest stretch in image coordinate space, thus building a correspondence between pedestrian crowd motion and the performance of a tracking algorithm. Moreover, we also propose a new head detector, HeadHunter, which is designed for small head detection in crowded scenes. We extend HeadHunter with a Particle Filter and a color histogram based re-identification module for head tracking. To establish this as a strong baseline, we compare our tracker with existing state-of-the-art pedestrian trackers on CroHD and demonstrate superiority, especially in identity preserving tracking metrics. With a light-weight head detector and a tracker which is efficient at identity preservation, we believe our contributions will serve useful in advancement of pedestrian tracking in dense crowds.