Multi-scale and real-time non-parametric approach for anomaly detection and localization☆
Highlights
► In this paper we present a non-parametric approach to anomaly detection in surveillance videos. ► The real-time system uses spatio-temporal features, integrated in a multi-scale approach. ► The system can localize anomalies temporally (at frame level) and spatially (within frame). ► The systems has been compared to state-of-the-art approaches on a real-world UCSD dataset. ► According to experiments our method consistently outperforms other real-time approaches.
Section snippets
Introduction and previous work
The real-world surveillance systems currently deployed are primarily based on the performance of human operators that are expected to watch, often simultaneously, a large number of screens (up to 50 [2]) that show streams captured by different cameras. One of the main tasks of security personnel is to perform proactive surveillance to detect suspicious or unusual behavior and individuals [3] and to react appropriately. As the number of CCTV streams increases, the task of the operator becomes
Scene representation
Modeling crowd patterns is one of the most complex contexts for detection of anomalies in video surveillance scenarios. Describing such statistics is extremely complex since, as stated in Section 1, the use of trajectories does not allow to capture all the possible anomalies that may occur, e.g. due to variations of scene appearance and the presence of unknown objects moving in the scene; this is due to the fact that object detection and tracking are often unfeasible both for computational
Real-time anomaly detection
Our system is able to learn from a normal data distribution fed as a training set but can also start without any knowledge of the scene, learning and updating the “normal behavior” profile dynamically, almost without any human intervention. The model can always be updated with a very simple procedure. Despite the simple formulation of this approach our system is able to model complex and crowded scenes, including both dynamic and static patterns.
Our technique is inspired by the one proposed in
Experimental results
We tested our approach on the UCSD1 anomaly dataset presented in [34], which provides frame-by-frame local anomaly annotation. The dataset consists of two subsets, corresponding to different scenes using fixed cameras that overlook pedestrian walkways: one (called Peds1) contains videos of people moving towards and away from the camera, with some perspective distortion; the other (called Peds2) shows pedestrian movement parallel to the
Conclusions
In this paper we have presented a multi-scale non-parametric anomaly detection approach that can be executed in real-time in a completely unsupervised manner. The approach is capable of localizing anomalies in space and time. We have also provided a straightforward procedure to dynamically update the learned model, to deal with scene changes that happen in real-world surveillance scenarios. Dense and overlapping spatio-temporal features, that model appearance and motion information, have been
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