  4D human perception plays an essential role in a myriad of applications, such
as home automation and metaverse avatar simulation. However, existing solutions
which mainly rely on cameras and wearable devices are either privacy intrusive
or inconvenient to use. To address these issues, wireless sensing has emerged
as a promising alternative, leveraging LiDAR, mmWave radar, and WiFi signals
for device-free human sensing. In this paper, we propose MM-Fi, the first
multi-modal non-intrusive 4D human dataset with 27 daily or rehabilitation
action categories, to bridge the gap between wireless sensing and high-level
human perception tasks. MM-Fi consists of over 320k synchronized frames of five
modalities from 40 human subjects. Various annotations are provided to support
potential sensing tasks, e.g., human pose estimation and action recognition.
Extensive experiments have been conducted to compare the sensing capacity of
each or several modalities in terms of multiple tasks. We envision that MM-Fi
can contribute to wireless sensing research with respect to action recognition,
human pose estimation, multi-modal learning, cross-modal supervision, and
interdisciplinary healthcare research.
