Anomaly detection in crowded scenes: technologies, challenges and opportunities

Abstract

The paper discusses advancements in intelligent video surveillance systems, particularly focused on anomaly detection in
crowded environments. These systems aim to enhance public safety by automatically detecting unusual behavior and potential threats
in real-time. Traditional video surveillance, relying heavily on human monitoring, faces limitations like reduced concentration and
slow response times. In contrast, intelligent surveillance uses machine learning and AI algorithms to process vast amounts of video
data, identifying patterns that deviate from normal behavior. Crowd anomaly detection is essential in densely populated areas like
transportation hubs, stadiums, and public squares. The diversity of anomalies, ranging from minor disruptions to serious threats such
as theft or terrorist attacks, presents a challenge for these systems. Anomalies can be difficult to detect due to their unpredictable
nature, and what constitutes an anomaly varies depending on the context. The paper highlights the need for robust systems that can
adapt to various environmental conditions and distinguish between normal variations and genuine threats. While supervised machine
learning models show promise, they often require large amounts of labeled data, which is difficult to obtain in real-world settings.
Unsupervised models and deep learning techniques, such as Convolution Neural Networks, have been effective in analyzing crowd
behavior and detecting anomalies. However, these methods still face challenges, including scalability, high false positive rates, and
the need for real-time processing in large-scale environments. The paper concludes by addressing the limitations of current crowd
anomaly detection methods, such as their computational costs, ethical concerns, and inability to detect novel anomalies. It suggests
directions for future research, including the integration of advanced learning techniques to improve system performance and
scalability.