Video anomaly detection using deep generative models

Video anomaly detection faces three challenges: a) no explicit definition of abnormality; b) scarce labelled data and c) dependence on hand-crafted features. This thesis introduces novel detection systems using unsupervised generative models, which can address the first two challenges. By working directly on raw pixels, they also bypass the last

MoWLD: a robust motion image descriptor for violence detection

© 2015, Springer Science+Business Media New York. Automatic violence detection from video is a hot topic for many video surveillance applications. However, there has been little success in designing an algorithm that can detect violence in surveillance videos with high performance. Existing methods typically apply the Bag-of-Words (BoW) model on local spatiotemporal descriptors. However, traditional spatiotemporal features are not discriminative enough, and also the BoW model roughly assigns each feature vector to only one visual word and therefore ignores the spatial relationships among the features. To tackle these problems, in this paper we propose a novel Motion Weber Local Descriptor (MoWLD) in the spirit of the well-known WLD and make it a powerful and robust descriptor for motion images. We extend the WLD spatial descriptions by adding a temporal component to the appearance descriptor, which implicitly captures local motion information as well as low-level image appear information. To eliminate redundant and irrelevant features, the non-parametric Kernel Density Estimation (KDE) is employed on the MoWLD descriptor. In order to obtain more discriminative features, we adopt the sparse coding and max pooling scheme to further process the selected MoWLDs. Experimental results on three benchmark datasets have demonstrated the superiority of the proposed approach over the state-of-the-arts

Multi-scale Spatial-temporal Interaction Network for Video Anomaly Detection

Video anomaly detection (VAD) is an essential yet challenge task in signal processing. Since certain anomalies cannot be detected by analyzing temporal or spatial information alone, the interaction between two types of information is considered crucial for VAD. However, current dual-stream architectures either limit interaction between the two types of information to the bottleneck of autoencoder or incorporate background pixels irrelevant to anomalies into the interaction. To this end, we propose a multi-scale spatial-temporal interaction network (MSTI-Net) for VAD. First, to pay particular attention to objects and reconcile the significant semantic differences between the two information, we propose an attention-based spatial-temporal fusion module (ASTM) as a substitute for the conventional direct fusion. Furthermore, we inject multi ASTM-based connections between the appearance and motion pathways of a dual stream network to facilitate spatial-temporal interaction at all possible scales. Finally, the regular information learned from multiple scales is recorded in memory to enhance the differentiation between anomalies and normal events during the testing phase. Solid experimental results on three standard datasets validate the effectiveness of our approach, which achieve AUCs of 96.8% for UCSD Ped2, 87.6% for CUHK Avenue, and 73.9% for the ShanghaiTech dataset

Look at Adjacent Frames: Video Anomaly Detection without Offline Training

We propose a solution to detect anomalous events in videos without the need to train a model offline. Specifically, our solution is based on a randomly-initialized multilayer perceptron that is optimized online to reconstruct video frames, pixel-by-pixel, from their frequency information. Based on the information shifts between adjacent frames, an incremental learner is used to update parameters of the multilayer perceptron after observing each frame, thus allowing to detect anomalous events along the video stream. Traditional solutions that require no offline training are limited to operating on videos with only a few abnormal frames. Our solution breaks this limit and achieves strong performance on benchmark datasets.Comment: Accepted in ECCV 2022 RW