We present a privacy-preserving indoor human tracking framework that
fuses millimeter-wave (mmWave) radar and long-wave infrared (thermal)
imaging without using RGB cameras. RGB images are used only for offline
annotation of the UTM multimodal dataset...
We present a privacy-preserving indoor human tracking framework that
fuses millimeter-wave (mmWave) radar and long-wave infrared (thermal)
imaging without using RGB cameras. RGB images are used only for offline
annotation of the UTM multimodal dataset; inference relies solely on
mmWave radar depth, thermal images, and thermal-based pseudo depth.
Using Faster R-CNN with a ResNet50-FPN backbone, we evaluate three
input configurations for human detection and headcount estimation: (1)
radar only, (2) radar + thermal, and (3) radar + thermal + thermal
pseudo depth. The third configuration adds a pseudo-depth channel
generated by a pre-trained monocular thermal depth network
(MonoTher-Depth). On UTM, radar + thermal consistently improves mAP
and counting MAE over radar-only inputs, with larger gains in
multi-person and small/partially occluded scenes. Adding thermal pseudo
depth yields further improvements, especially in complex backgrounds
prone to false positives.
For qualitative tracking analysis, we connect frame-wise detections into
trajectories through a lightweight association step based on bounding-box
overlap and center-point distance, and we examine temporal stability
across the three configurations. These results suggest the feasibility of
practical indoor monitoring—presence, location, headcount, and coarse
trajectory-level analysis—using only mmWave radar, thermal imaging, and
thermal-based pseudo depth.