TADAR: Thermal Array-based Detection and Ranging for Privacy-Preserving Human Sensing

TL;DR

TADAR introduces a novel thermal array-based system that estimates 3D human positions for privacy-preserving sensing, achieving high detection accuracy and practical application potential in indoor environments.

Contribution

It is the first system to extend thermal array outputs to 3D depth estimation, enabling privacy-preserving human sensing with multi-user detection and ranging capabilities.

Findings

Achieves 88.8% F1 score in multi-user detection

Ranging accuracy of 32.0 cm overall, 20.1 cm within 3 meters

Demonstrates effectiveness in fall detection and occupancy estimation

Abstract

Human sensing has gained increasing attention in various applications. Among the available technologies, visual images offer high accuracy, while sensing on the RF spectrum preserves privacy, creating a conflict between imaging resolution and privacy preservation. In this paper, we explore thermal array sensors as an emerging modality that strikes an excellent resolution-privacy balance for ubiquitous sensing. To this end, we present TADAR, the first multi-user Thermal Array-based Detection and Ranging system that estimates the inherently missing range information, extending thermal array outputs from 2D thermal pixels to 3D depths and empowering them as a promising modality for ubiquitous privacy-preserving human sensing. We prototype TADAR using a single commodity thermal array sensor and conduct extensive experiments in different indoor environments. Our results show that TADAR achieves a mean F1 score of 88.8% for multi-user detection and a mean accuracy of 32.0 cm for multi-user ranging, which further improves to 20.1 cm for targets located within 3 m. We conduct two case studies on fall detection and occupancy estimation to showcase the potential applications of TADAR. We hope TADAR will inspire the vast community to explore new directions of thermal array sensing, beyond wireless and acoustic sensing. TADAR is open-sourced on GitHub: https://github.com/aiot-lab/TADAR.