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Human Activity Recognition (HAR) utilizing Channel State Information (CSI) extracted from WiFi signals has garnered substantial interest across various domains and applications. This field’s potential paths and applications extend beyond CSI-based HAR and include smart homes, assisted living, security, gaming, surveillance, and context-aware computing. The ability of deep learning algorithms to effectively process and interpret CSI data opens up new possibilities for accurate and robust human activity recognition in real-world scenarios. However, traditional Recurrent Neural Networks (RNN) models, such as Long Short-Term Memory (LSTM) and Gated Recurrent Unit (GRU), rely solely on their internal memory cells to maintain information over time. Important details might be diluted or lost within the memory cells in complex CSI sequences. To address this limitation, we propose a lightweight approach that incorporates a multi-head adaptive attention weight mechanism MHAAM into the HAR framework. The multi-head attention mechanism allows the model to attend to different informative patterns within the CSI data simultaneously, capturing fine-grained temporal dependencies and improving the model’s ability to recognize complex activities. The implemented models effectively filter out noise and irrelevant information by assigning higher weights to informative CSI features, further enhancing activity classification accuracy. Experimental evaluations and comparative analyses of HAR for seven activities demonstrate that attention-based RNN models with multi-head attention consistently outperform traditional RNN models. The multi-head attention mechanism achieves improved generalization and testing for seven common human activities and environments, leading to a higher complex human activity classification accuracy of up to 98.5%. [ABSTRACT FROM AUTHOR]

Monitoring and inferring socio-cognitive behaviors through crowd analysis can help us to understand many processes. Be it people in crowded environments, road traffic or even a flock of fish, situational awareness becomes critical for creating adequate disaster response, providing incident management, exercising control, etc. Recent researches have indicated that crowd modeling is conventionally based on density analysis. However, socio-cognitive behavior studies have demonstrated that crowds often display a wide variety of behaviors that arise spontaneously from the collective motions of unconnected individuals. Therefore, behavior analysis employing physics-based approaches only, thereby neglecting the socio-psychological aspects, may present diverse challenges to accurate inference. This means that by identifying and modeling some of the interacting agents that underpin the evolution of such behaviors, we can deliver contexts that can help in the autonomous analysis of social and antisocial behaviors in crowded environments. This paper discusses these issues from the machine vision perspective. In particular, socio-cognitive models of crowds are linked to low-level mechanisms of crowd modeling and feature extraction. A survey of recent works on crowd behavior analysis is conducted under a proposed behavioral categorization based on the level of the performed analysis and identified behaviors. Finally, discussions and recommendations are provided toward the advancement in the field. [ABSTRACT FROM AUTHOR]

Visual recognition of crowd dynamics has had a huge impact on several applications including surveillance, situation awareness, homeland security and intelligent environments. However, the state-of-the-art in crowd analysis has become diverse due to factors such as: (a) the underlying definition of a crowd, (b) the constituent elements of the crowd processing model, (c) its application, hence (d) the dataset and (e) the evaluation criteria available for benchmarking. Although such diversity is healthy, the techniques for crowd modelling thus developed have failed to establish credibility therefore becoming unreliable and of questionable validity across different research disciplines. This paper aims to give an account of such issues by deducing key statistical evidence from the existing literature and providing recommendations towards focusing on the general aspects of techniques rather than any specific algorithm. The advances and trends in crowd analysis are drawn in the context of crowd modelling studies published in leading journals and conferences over the past 7 years. Finally, this paper shall also provide a qualitative and quantitative comparison of some existing methods using various publicly available crowd datasets to substantiate some of the theoretical claims. [ABSTRACT FROM AUTHOR]