Where and What: Contextual Dynamics-Aware Anomaly Detection in Surveillance Videos.

Anomaly detection in surveillance videos is a challenging task due to the diversity of anomalous video content and duration. In this paper, we consider video anomaly detection as a regression problem with respect to anomaly scores of video clips under weak supervision. Hence, we propose an anomaly detection framework, called Anomaly Regression Net (ARNet), which only requires video-level labels in training stage. Further, to learn discriminative features for anomaly detection, we design a dynamic multiple-instance learning loss and a center loss for the proposed AR-Net. The former is used to enlarge the inter-class distance between anomalous and normal instances, while the latter is proposed to reduce the intra-class distance of normal instances. Comprehensive experiments are performed on a challenging benchmark: ShanghaiTech. Our method yields a new state-of-the-art result for video anomaly detection on ShanghaiTech dataset.

Several computer vision algorithms have been proposed to detect anomalous activities (robberies, murders, vandalism, among others) in videos. According to the learning approach, they can be classified into probabilistic distribution modeling, sparse coding, and deep learning based methods. The main drawbacks of these approaches are (i) extraction of low-level features that do not capture complex behaviors of instances on the scene, (ii) generation of features from irrelevant regions, (iii) overlooking of relationships among objects, and (iv) omission of long-term dependencies. To solve these issues, we propose a deep learning architecture that leverages the relationships among objects. It achieves this by using an attention mechanism and learning long-term dependencies using a multilayer recurrent neural network (multilayer LSTM). An AUC score of 0.749 on the UCF-Crime dataset confirms that the proposed algorithm competes effectively against several state-of-the-art approaches for anomaly detection in surveillance videos. It also explains the relationship between regions in the video frames and the anomaly detections.

For enhancing public safety, a surveillance system is essential. Specifically, video surveillance is the most popular way to maintain safety in public and private areas. The detection and recognition of abnormal activity is difficult due to a complex environment, video quality, and varying noise levels. Addressing the challenges of accuracy and video processing, the proposed study uses a cross-attention network with feature fusion to improve the recognition of abnormal activity in complex scenarios. Cross-attention helps to capture contextual information from different videos. The proposed model combines an innovative method of cross attention and feed-forward attention with latent space representation-based fusion, aiming to improve accuracy. The simulation of the study uses two benchmark datasets, UCF and UCSD and achieves remarkable performance with 97.1 % and 91.31 % accuracy. A simulation study has also demonstrated a comparative analysis with different convolution and attention networks for anomaly detection. This study proposes an effective video processing scheme with wide practical potential. The study also provides a new perspective and methodological basis for future research and applications in related fields.

This paper aims to address the problem of behavioural anomaly detection in surveillance videos. We propose a novel framework tailored towards global video behaviour anomaly detection in complex outdoor scenes involving multiple temporal processes caused by correlated behaviours of multiple objects. Specifically, given a complex wide-area scene that has been segmented automatically into semantic regions where behaviour patterns are represented as discrete local atomic events, we formulate a novel Cascade of Dynamic Bayesian Networks (CasDBNs) to model behaviours with complex temporal correlations by utilising combinatory evidences collected from local atomic events. Using a cascade configuration not only allows for accurate detection of video behaviour anomalies, more importantly, it also improves the robustness of the model in dealing with the inevitable presence of errors and noise in the behaviour representation resulting less false alarms. We evaluate the effectiveness of the proposed framework on a real world traffic scene. The results demonstrate that the framework is able to detect not only anomalies that are visually obvious, but also those that are ambiguous or supported only by very weak visual evidence, e.g. those that can be easily missed by a human observer.

Event detection in crowded surveillance videos is a challenging yet important problem. In this paper, we present our eSur (Event detection system on SURveillance video) system, which is derived from TRECVid'12 surveillance tasks. Currently, eSur attempts to detect two categories of events: 1) pair-wise events (e.g., PeopleMeet, PeopleSplitUp and Embrace); 2) action-like events (e.g., ObjectPut, CellToEar, PersonRuns and Pointing). In eSur system, we first employ people detection and tracking algorithms to locate target persons in 3D space-time domain. Then the video sequences in which target persons occur are partitioned into several spatio-temporal cubes. Visual features (i.e. cubic feature and MoSIFT) are computed over these cubes. After that, a sequence learning method, (namely SVM with dynamic time alignment kernel), is employed to infer the existence of an event for the video sequence. According to the TRECVid SED formal evaluation, eSur has yielded fairly encouraging results on TRECVid'12 dataset.

Intelligent video surveillance systems with anomaly detection capabilities are indispensable for outdoor security. Video anomaly detection (VAD) is usually performed by learning patterns representing normal events and declaring an anomaly when an abnormal pattern is encountered. However, the features of normal patterns in a video often vary with time as real-world videos are non-stationary in nature, which makes its handling essential during VAD. To this end, we propose an approach for anomaly detection in videos, where a novel deep temporally recursive differencing network (DDN) diminishes the adverse effects of the non-stationary nature on VAD. The DDN consists of multiple layers of differencing operators of optimized orders, where every two consecutive layers are separated by a suitable nonlinearity. Spatial and temporal features are extracted from nonoverlapping blocks in video frames and fed to the DDN. While the spatial feature is obtained using a pretrained network, our temporal feature computation involves the use of FlowNetS with a new training strategy that does not require ground truth. The features at the output of DDN are used in a predictor based on autoregression and moving average of the regression errors. Then, the predictor's output estimates are compared to the corresponding actual values for anomaly detection, which also involves block-level selection and consistency check. Qualitative evaluation and quantitative comparison with several existing approaches on multiple standard datasets demonstrate the effectiveness of the proposed VAD approach. An ablation study highlighting the significance of the various components of our approach and a hyperparameter analysis are also provided.

Anomaly detection in videos is the task of identifying frames from a video sequence that depict events that do not conform to expected behavior, which is an extremely challenging task due to the ambiguous and unbounded properties of anomalies. With the development of deep learning, video anomaly detection methods based on deep neural networks have made great progress. The existing methods mainly follow two routes, namely, frame reconstruction and frame prediction. Due to the powerful generalization ability of neural networks, the application of reconstruction-based methods is limited. Recently, anomaly detection methods based on prediction have achieved advanced performance. However, their performance suffers when they cannot guarantee lower prediction errors for normal events. In this paper, we propose a novel future frame prediction model based on a bidirectional retrospective generation adversarial network (BR-GAN) for anomaly detection. To predict a future frame with higher quality for normal events, first, we propose a bidirectional prediction combined with a retrospective prediction method to fully mine the bidirectional temporal information between the predicted frame and the input frame sequence. Then, the intensity and gradient loss between the predicted frame and the actual frame together with an adversarial loss are used for appearance (spatial) constraints. In addition, we propose a sequence discriminator composed of a 3-dimensional (3D) convolutional neural network to capture the long-term temporal relationships between frame sequences composed of predicted frames and input frames; this network plays a crucial role in maintaining the motion (temporal) consistency of the predicted frames for normal events. Such appearance and motion constraints further facilitate future frame prediction for normal events, and thus, the prediction network can be highly capable of distinguishing normal and abnormal patterns. Extensive experiments on benchmark datasets demonstrate that our method outperforms most existing state-of-the-art methods, validating the effectiveness of our method for anomaly detection.

This paper presents a novel hybrid approach for real-time anomaly detection in video surveillance systems by integrating YOLOv8 object detection with advanced motion-based analysis techniques. The proposed system addresses critical limitations of existing single-modality detection methods through innovative fusion of deep learning and temporal analysis. The architecture incorporates parallel processing pipelines for YOLOv8 detection and optical flow computation, combined with an isolation forest-based anomaly decision framework that leverages historical detection patterns. Experimental evalution on a custom dataset of 5,000 surveillance video clips demonstrates superior performance with 92.3% accuracy, 89.7% precision, 94.1% recall, and 91.8% F1-score, while maintaining real-time processing at 30 FPS. The system significantly outperforms traditional approaches with 15.2% accuracy improvement over YOLO-only methods and 18.7% improvement over motion-only techniques. The proposed hybrid framework provides robust anomaly detection capabilities suitable for practical deployment in security-critical surveillance applications with reduced false positive rates and enhanced temporat consistence.

During past few years’ significant usage of video monitoring has been observed in several places. Video monitoring has always helped in improvement of security specific aspects. These systems provide major helping hand in monitoring through multiple object detection methods. However, there are certain challenges related to weather conditions which needs to be addressed. In view of this in this paper, we study multiple object detection in surveillance videos through hybrid deep gaussian mixture ensembles. This method integrates multiple deep gaussian mixture components to form ensembles which helps to develop multiple object detection solutions in surveillance videos. The computational system consists of ensemble of three major deep gaussian mixture components. The ensemble pipeline is formed with augmenting, bagging and stacking methods. The ensemble consists of hybrid object detection paradigm with steps background analysis, video pre-processing, data integration, object detection, foreground detection and post-processing. The computational pipeline is successfully experimented with ViSOR and CDnet 2014 benchmarked datasets. All results are validated with accuracy, precision, sensitivity or recall, specificity, F1-Score and RMSE metrics. Several comparative studies are performed with state-of-the-art methods as well as baselines. The experimental results demonstrate superiority of this method in comparison with other methods. Ablation studies have also been performed here with superior results. This system presents robustness in multiple object detection for real life challenges such as sudden illumination variation, shadow presence, long term occlusion and formation of dynamic backgrounds. It provides cost-effective, more profitable, efficient and sustainable real time multiple object detection solutions

Fast fire flame detection in surveillance video using logistic regression and temporal smoothing

For abnormal gait detection in surveillance videos, the existing methods suffer from that they are unable to recognize novel types of anomalies if the corresponding prototypes have not been included in the training data for supervised machine learning but it is impractical to foresee all types of anomalies. This research aims to solve the problem in an unsupervised manner, which does not rely on any prior knowledge regarding abnormal prototypes and avoids time-consuming machine learning over large-scale high-dimensional features. The intuition is that normal gait is nearly periodic signal and anomalies may disturb such periodicity. Hence, the time-varying ratio of width to height of a walking person is transformed to frequency domain using Fast Fourier Transform (FFT), and the standard deviation over spectrum is used as an indicator of anomalies, subject to any sudden change to break the normally periodical walking rhythm. The experimental results demonstrate its precision.

Anomaly detection in crowd surveillance videos is a critical task for ensuring public safety and security. In this research paper, we propose a comprehensive framework for anomaly detection using deep learning techniques, specifically Recurrent Neural Networks (RNNs), Convolutional Neural Networks (CNNs), and Generative Adversarial Networks (GANs). Our objective is to narrow the gap between computational complexity and detection effectiveness while satisfying the demand for explainability in anomaly detection systems. The proposed framework leverages the UCSD Ped2 dataset and focuses on incorporating spatial constraints to enhance anomaly detection performance. We introduce novel approaches for feature extraction and anomaly detection using GANs, aiming to capture essential spatial and temporal information while reducing computational complexity. Specifically, we develop encoders within the GAN framework to map input data to a lower-dimensional latent space and perform anomaly detection based on the similarity between latent codes. Through extensive experimentation and evaluation, we compare the performance of RNNs, CNNs, and GANs in detecting anomalies in crowd surveillance videos. Various evaluation metrics, including precision, recall, F1 score, ROC-AUC, and PR-AUC, is considered to assess the effectiveness of each approach. Additionally, they studied hyperparameters such as learning rate, batch size, network architecture, and GAN-specific parameters to optimize anomaly detection performance. Our results demonstrate the usefulness of the proposed framework in achieving robust and explainable anomaly detection in crowd surveillance videos. By combining advanced deep learning techniques with spatial constraints and explainability considerations, our research contributes to the development of more reliable and interpretable anomaly detection systems for real-world applications.

In this paper, global abnormal events detection in the crowded scene is proposed. The proposed algorithm is based on a hierarchical approach. The method uses the histogram of optical flow orientation as a feature descriptor along with the magnitude of the optical flow to capture the motion. The nonlinear one-class support vector machine (SVM) classification algorithm is used to learn the normal events from the training data. After learning, one-class SVM detects abnormal events in the frame. The algorithm is fast with improved accuracy since it omits the background subtraction step and adopts hierarchy. The proposed method is tested on benchmark UMN unusual crowd activity dataset which contain global abnormal events. Promising results are reported which evaluates the performance of the proposed method.

Crowd Event Detection in Surveillance Video - An Approach based on Optical Flow High-frequency Feature Analysis

Anomaly event detection in crowd scenes is extremely important; however, the majority of existing studies merely use hand-crafted features to detect anomalies. In this study, a novel unsupervised deep learning framework is proposed to detect anomaly events in crowded scenes. Specifically, low-level visual features, energy features, and motion map features are simultaneously extracted based on spatiotemporal energy measurements. Three convolutional restricted Boltzmann machines are trained to model the mid-level feature representation of normal patterns. Then a multimodal fusion scheme is utilized to learn the deep representation of crowd patterns. Based on the learned deep representation, a one-class support vector machine model is used to detect anomaly events. The proposed method is evaluated using two available public datasets and compared with state-of-the-art methods. The experimental results show its competitive performance for anomaly event detection in video surveillance.