3D Gaussian Splatting (3DGS) achieves high-fidelity novel view synthesis, but its application in online long-sequence scenarios is still restricted. Existing methods either rely on slow per-scene optimization or lack efficient frame-wise 3DGS updates, making them unsuitable for online long-sequence videos. In this paper, we propose LongSplat, an online real-time 3D Gaussian reconstruction framework designed for long-sequence image input. The core idea of LongSplat is to maintain a global 3DGS set and design a streaming 3DGS update mechanism that selectively compressing redundant historical Gaussians and introducing new Gaussians by comparing the current observations with the historical Gaussian. To achieve this goal, we design a Gaussian-Image Representation (GIR), which encodes 3D Gaussian parameters into a structured, image-like 2D format. GIR simultaneously enables identity-aware redundancy compression as well as the fusion of current view and historical Gaussians, which are used for online reconstruction and adapt the model to long sequences without overwhelming memory or computational costs. Extensive experiments demonstrate that LongSplat achieves state-of-the-art efficiency-quality trade-offs in real-time novel view synthesis, delivering real-time reconstruction while reducing Gaussian counts by 44% compared to per-pixel prediction paradigms.

Compositional generalization has achieved substantial progress in computer vision on pre-collected training data. Nonetheless, real-world data continually emerges, with possible compositions being nearly infinite, long-tailed, and not entirely visible. Thus, an ideal model is supposed to gradually improve the capability of compositional generalization in an incremental manner. In this paper, we explore Composition-Incremental Learning for Compositional Generalization (CompIL) in the context of the compositional zero-shot learning (CZSL) task, where models need to continually learn new compositions, intending to improve their compositional generalization capability progressively. To quantitatively evaluate CompIL, we develop a benchmark construction pipeline leveraging existing datasets, yielding MIT-States-CompIL and C-GQA-CompIL. Furthermore, we propose a pseudo-replay framework utilizing a visual synthesizer to synthesize visual representations of learned compositions and a linguistic primitive distillation mechanism to maintain aligned primitive representations across the learning process. Extensive experiments demonstrate the effectiveness of the proposed framework.

Most video anomaly detection methods discriminate events that deviate from normal patterns as anomalies. However, these methods are prone to interferences from event-irrelevant factors, such as background textures and object scale variations, incurring an increased false detection rate. In this paper, we propose to explicitly learn event-relevant factors to eliminate the interferences from event-irrelevant factors on anomaly predictions. To this end, we introduce a causal generative model to separate the event-relevant factors and event-irrelevant ones in videos, and learn the prototypes of event-relevant factors in a memory augmentation module. We design a causal objective function to optimize the causal generative model and develop a counterfactual learning strategy to guide anomaly predictions, which increases the influence of the event-relevant factors. The extensive experiments show the effectiveness of our method for video anomaly detection.

Learning multiple pretext tasks is a popular approach to tackle the nonalignment problem in unsupervised video anomaly detection. However, the conventional learning method of simultaneously learning multiple pretext tasks, is prone to sub-optimal solutions, incurring sharp performance drops. In this paper, we propose to sequentially learn multiple pretext tasks according to their difficulties in an ascending manner to improve the performance of anomaly detection. The core idea is to relax the learning objective by starting with easy pretext tasks in the early stage and gradually refine it by involving more challenging pretext tasks later on. In this way, our method is able to reduce the difficulties of learning and avoid converging to sub-optimal solutions. Specifically, we design a tailored sequential learning order for three widely-used pretext tasks. It starts with frame prediction task, then moves on to frame reconstruction task and last ends with frame-order classification task. We further introduce a new contrastive loss which makes the learned representations of normality more discriminative by pushing normal and pseudo-abnormal samples apart. Extensive experiments on three datasets demonstrate the effectiveness of our method.

This paper presents a framework for telepresence operation by touching live video on a touchscreen. Our goal is to enable users to use a smartpad to teleoperate everyday objects by touching the objects’ live video they are watching. To this end, we coined the term “teleinteractive device” to describe such an object with an identity, an actuator, and a communication network. We developed a touchable live video image-based user interface (TIUI) that empowers users to teleoperate any teleinteractive device by touching its live video with touchscreen gestures. The TIUI contains four modules — touch, control, recognition, and knowledge — to perform live video understanding, communication, and control for telepresence operation. We implemented a telepresence operation system that consists of a telepresence robot and teleinteractive devices at a local site, a smartpad with the TIUI at a remote site, and communication networks connecting the two sites. We demonstrated potential applications of the system in remotely controlling telepresence robots, opening doors with access control panels, and pushing power wheelchairs. We conducted user studies to show the effectiveness of the proposed framework.

We propose a novel method of registering less-overlap RGB-D scans. Our method learns global information of a scene to construct a panorama, and aligns RGB-D scans to the panorama to perform registration. Different from existing methods that use local feature points to register less-overlap RGB-D scans and mismatch too much, we use global information to guide the registration, thereby allevi-ating the mismatching problem by preserving global consis-tency of alignments. To this end, we build a scene inference network to construct the panorama representing global in-formation. We introduce a reinforcement learning strategy to iteratively align RGB-D scans with the panorama and re-fine the panorama representation, which reduces the noise of global information and preserves global consistency of both geometric and photometric alignments. Experimental results on benchmark datasets including SUNCG, Matterport, and ScanNet show the superiority of our method.

Video anomaly detection aims to discriminate events that deviate from normal patterns in a video. Modeling the decision boundaries of anomalies is challenging, due to the uncertainty in the probability of deviating from normal patterns. In this paper, we propose a deep evidential reasoning method that explicitly learns the uncertainty to model the boundaries. Our method encodes various visual cues as evidences representing potential deviations, assigns beliefs to the predicted probability of deviating from normal patterns based on the evidences, and estimates the uncertainty from the remained beliefs to model the boundaries. To do this, we build a deep evidential reasoning network to encode evidence vectors and estimate uncertainty by learning evidence distributions and deriving beliefs from the distributions. We introduce an unsupervised strategy to train our network by minimizing an energy function of the deep Gaussian mixed model (GMM). Experimental results show that our uncertainty score is beneficial for modeling the boundaries of video anomalies on three benchmark datasets.

We propose a novel method of exploiting informative video segments by learning segment weights for temporal action localization in untrimmed videos. Informative video segments represent the intrinsic motion and appearance of an action, and thus contribute crucially to action localization. The learned segment weights represent the informativeness of video segments to recognize actions and help infer the boundaries required to temporally localize actions. We build a supervised temporal attention network (STAN) that includes a supervised segment-level attention module to dynamically learn the weights of video segments, and a feature-level attention module to effectively fuse multiple features of segments. Through the cascade of the attention modules, STAN exploits informative video segments and generates descriptive and discriminative video representations. We use a proposal generator and a classifier to estimate the boundaries of actions and classify the classes of actions. Extensive experiments are conducted on two public benchmarks, i.e., THUMOS2014 and ActivityNet1.3. The results demonstrate that our proposed method achieves competitive performance compared with existing state-of-the-art methods. Moreover, compared with the baseline method that treats video segments equally, STAN achieves significant improvements with an increase of the mean average precision from 30.4% to 39.8% on the THUMOS2014 dataset, and from 31.4% to 35.9% on the ActivityNet1.3 dataset, demonstrating the effectiveness of learning informative video segments for temporal action localization.

Abnormal event detection aims to identify the events that deviate from expected normal patterns. Existing methods usually extract normal spatio-temporal patterns of appearance and motion in a separate manner, which ignores low-level correlations between appearance and motion patterns and may fall short of capturing fine-grained spatio-temporal patterns. In this paper, we propose to simultaneously learn appearance and motion to obtain fine-grained spatio-temporal patterns. To this end, we present an adversarial 3D convolutional auto-encoder to learn the normal spatio-temporal patterns and then identify abnormal events by diverging them from the learned normal patterns in videos. The encoder captures the low-level correlations between spatial and temporal dimensions of videos, and generates distinctive features representing visual spatio-temporal information. The decoder reconstrucccts the original video from the encoded features representing by 3D de-convolutions and learns the normal spatio-temporal patterns in an unsupervised manner. We introduce the denoising reconstruction error and adversarial learning strategy to train the 3D convolutional auto-encoder to implicitly learn accurate data distributions that are considered normal patterns, which benefits enhancing the reconstruction ability of the auto-encoder to discriminate abnormal events. Both the theoretical analysis and the extensive experiments on four publicly available datasets demonstrate the effectiveness of our method.

In this paper, we propose a scene-aware context reasoning method that exploits context information from visual features for unsupervised abnormal event detection in videos, which bridges the semantic gap between visual context and the meaning of abnormal events. In particular, we build na spatio-temporal context graph to model visual context information including appearances of objects, spatio-temporal relationships among objects and scene types. The context information is encoded into the nodes and edges of the graph, and their states are iteratively updated by using multiple RNNs with message passing for context reasoning. To infer the spatio-temporal context graph in various scenes, we develop a graph-based deep Gaussian mixture model for scene clustering in an unsupervised manner. We then compute frame-level anomaly scores based on the context information to discriminate abnormal events in various scenes. Evaluations on three challenging datasets, including the UCF-Crime, Avenue, and ShanghaiTech datasets, demonstrate the effectiveness of our method.

Automatically detecting anomalies in videos is a challenging problem due to non-deterministic definitions of abnormal events and lack of sufficient training data. To address these issues, we propose an autoencoder coupled with attention model to discover normal patterns in videos via adversarial learning. Abnormal events are detected by diverging them from the normal patterns with the reconstruction error produced by the autoencoder. To this end, we build an end-to-end trainable adversarial attention-based autoencoder network, called Ada-Net, to make the reconstructed frames indistinguishable from original frames. The Ada-Net combines an autoencoder network and a GAN model that is used to benefit enhancing the reconstruction ability of the autoencoder. To further improve the reconstruction performance, we integrate an attention model into the decoder to dynamically select informative parts of encoding features for decoding. The attenion mechanism is helpful to preserving important information for learning intrinsic normal patterns. Evaluations on four challenging datasets, including the Subway, the UCSD Pedestrian, the CUHK Avenue, and the ShanghaiTech datasets, demonstrate the effectiveness of the proposed method.