CamSense: A camera-based contact-less heart activity monitoring

Remote Photoplythysmograpy (rPPG) systems enable contactless heart activities (heart rate, heart rate variability) monitoring by estimating Photoplethysmogram (PPG) signal, blood’s volumetric variation in the skin tissues, leveraging the occurred diffused reflection from the exposed skin in skin video. They can primarily monitor heart activities using off-the-shelf video sensors while ensuring the safety of concerned individuals during contagious diseases. However, developing the rPPG systems is challenging due to the marginal presence of PPG signal in the video stream, data variations, limited and noisy rPPG data. In this regard, we propose an end-to-end deep learning-based approach for camera-based contactless sensing CamSense for recovering PPG signals from consecutive raw video frames. Firstly, we design and validate a personalized model to bypass data variation and noise across data collection with a modified objective function under realistic settings. Secondly, we explore and design multi-task learning (MTL) network to address the rPPG data variabilities for learning generalized rPPG representations. We also propose a transfer learning approach that integrates an efficient weight initialization to scale the rPPG systems under different domains and settings for fast and generalized training and inferences. Finally, we offer a new dataset, MPSC-rPPG dataset, containing multiple RGB videos and corresponding PPG ground truth for end–end rPPG network training. We evaluate CamSense on two public datasets and our MPSC-rPPG dataset across multiple subjects and heterogeneous camera sensors such as DSLR and near-infrared sensors with different ground truth provider PPG sensors (wrist, finger) to showcase its’ generalizability. We further validate our components’ design choices by performing ablation studies using different settings. Our developed model approximates accurate PPG signals with an average root mean square error (RMSE) of 0.08, 0.10, and 0.06 for personalized models, MTL model, and transfer learnings on the held-out test videos.

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