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Traffic prediction methods on a single-source data have achieved excellent results in recent years, especially the Graph Convolutional Networks (GCN) based models with spatio-temporal dependency. In reality, various modes of urban transportation operate simultaneously. They influence and complement each other in common space-time occasions, constituting the transportation system dynamically. Thus, traffic data from multiple sources is ostensibly heterogeneous, but internally correlated. The typical single data driven models are, however, not universally applicable for heterogeneous traffic data. To address this issue, we propose a Multi-task Hypergraph Convolutional Neural Network (MT-HGCN) for the multi-source traffic prediction problem. The framework consists of a main task and a related task. Both tasks are based on Hypergraph Convolutional Neural Networks (HGCN) and are devoted to two prediction problems. Furthermore, the tasks are bridged by a feature compress unit, which models the correlation and shares the latent feature to improve the performance of the main task. The node-level forecasting has been evaluated on historical datasets of Beijing to verify the effectiveness of the proposed method. Compared with the state-of-the-arts, the superior performance of the proposed method can be obtained. [ABSTRACT FROM AUTHOR]

Analyzing the traffic state of large citywide networks is an inherently difficult task. Various data issues, traffic signals, stops signs and other flow inhibitors of the network-level traffic state make the analysis more difficult than that under the small-scale local traffic state. To address this challenge, we propose a method based on spatio-temporal non-negative matrix factorization (ST-NMF), which is used for road network traffic pattern analysis. The method can be further extended to traffic data reconstruction and traffic prediction. In order to analyze traffic patterns, the proposed spatio-temporal non-negative matrix factorization model represents the network traffic as a linear combination of several basic patterns, which is also interpreted as the dynamics of spatial traffic characteristics over time in low-dimensional space. By the visual display of the spatial and temporal patterns and the assistance of clustering methods, the traffic pattern features are extracted. In the extended applications, data reconstruction relies on the sampling representation of missing data by ST-NMF, and data prediction is based on the prediction of the temporal patterns by ST-NMF. Through our method, we can not only obtain a high-quality data foundation, but also explore typical spatio-temporal patterns and general predictions of the future traffic state. The analysis results have important guiding significance on the management of intelligent transportation systems. Experiments on real-world traffic data are provided to verify the validity of our proposed approach. [ABSTRACT FROM AUTHOR]

Traffic prediction plays an essential role in intelligent transportation system. Accurate traffic prediction can assist route planing, guide vehicle dispatching, and mitigate traffic congestion. This problem is challenging due to the complicated and dynamic spatio-temporal dependencies between different regions in the road network. Recently, a significant amount of research efforts have been devoted to this area, especially deep learning method, greatly advancing traffic prediction abilities. The purpose of this paper is to provide a comprehensive survey on deep learning-based approaches in traffic prediction from multiple perspectives. Specifically, we first summarize the existing traffic prediction methods, and give a taxonomy. Second, we list the state-of-the-art approaches in different traffic prediction applications. Third, we comprehensively collect and organize widely used public datasets in the existing literature to facilitate other researchers. Furthermore, we give an evaluation and analysis by conducting extensive experiments to compare the performance of different methods on a real-world public dataset. Finally, we discuss open challenges in this field. [ABSTRACT FROM AUTHOR]

Traffic situation generation is of importance in the intelligent transportation field, evaluating and simulating the macroscopic traffic conditions. The government often uses the historical traffic data on the same weekday to analyze the future traffic situations, which works unfavorably due to some traffic-related information deficiency, such as weather, location, traffic accidents, social activities and so on. Therefore, how to accurately generate the traffic situation is a challenging problem. Fortunately, massive traffic-related information spread in social media often indicates the traffic situation variation trend, which provides the sufficient information for the traffic situation generation. In this paper, we propose a novel Text-to-Traffic generative adversarial network framework ($\text{T}^{2}$ GAN), which fuses the traffic data and the semantic information collected from social media to generate the traffic situation. To reduce the huge gap between the above two modalities and improve the authenticity of the generated traffic situation, we raise a global-local loss. Additionally, we build a heterogeneous dataset containing the traffic-related text data collected from social media and the corresponding traffic passenger flow data. Experimental results show that the proposed methods are obviously better than many outstanding traffic situation generation methods based on neural networks. [ABSTRACT FROM AUTHOR]

Probabilistic linear discriminant analysis (PLDA) is a very effective feature extraction approach and has obtained extensive and successful applications in supervised learning tasks. It employs the squared $L_{2}$ -norm to measure the model errors, which assumes a Gaussian noise distribution implicitly. However, the noise in real-life applications may not follow a Gaussian distribution. Particularly, the squared $L_{2}$ -norm could extremely exaggerate data outliers. To address this issue, this article proposes a robust PLDA model under the assumption of a Laplacian noise distribution, called L1-PLDA. The learning process employs the approach by expressing the Laplacian density function as a superposition of an infinite number of Gaussian distributions via introducing a new latent variable and then adopts the variational expectation–maximization (EM) algorithm to learn parameters. The most significant advantage of the new model is that the introduced latent variable can be used to detect data outliers. The experiments on several public databases show the superiority of the proposed L1-PLDA model in terms of classification and outlier detection. [ABSTRACT FROM AUTHOR]

Traffic forecasting is a challenging problem in the transportation research field as the complexity and non-stationary changing of the traffic data, thus the key to the issue is how to explore proper spatial and temporal characteristics. Based on this thought, many creative methods have been proposed, in which Graph Convolution Network (GCN) based methods have shown promising performance. However, these methods depend on the graph construction, which mainly uses the prior knowledge of the road network. Recently, some works realized the fact of the road network graph changing and tried to construct dynamic graphs for GCN, but they do not fully exploit the spatial and temporal properties of the traffic data in the graph construction. In this paper, we propose a novel dynamic graph convolution network for traffic forecasting, in which a latent network is introduced to extract spatial-temporal features for constructing the dynamic road network graph matrices adaptively. The proposed method is evaluated on several traffic datasets and the experimental results show that it outperforms the state of the art traffic forecasting methods. The website of the code is https://github.com/guokan987/DGCN.git. [ABSTRACT FROM AUTHOR]

Traffic flow data has three main characteristics: large amount of noise and incompleteness, temporal and spatial correlation, and dynamic sequential property. Problems of noise, loss and incompleteness could decrease the prediction performance and make it difficult for transportation system management. Inspired by recent work on low rank representation (LRR) and dynamic mode decomposition (DMD), we propose a Low Rank Dynamic Mode Decomposition (LRDMD) model which solves the aforementioned problems simultaneously. LRDMD predicts traffic flow by using a state transition matrix which characterizes the relationship between temporally neighboring fragments of traffic flow with low rank regularization. We conduct experiments of traffic flow prediction of different time intervals using loop coil detector data of Qingdao, and the results show that LRDMD outperforms state-of-the-art methods. [ABSTRACT FROM AUTHOR]

Subspace data representation has recently become a common practice in many computer vision tasks. Low-rank representation (LRR) is one of the most successful models for clustering vectorial data according to their subspace structures. This paper explores the possibility of extending LRR for subspace data on Grassmann manifold. Rather than directly embedding the Grassmann manifold into the symmetric matrix space, an extrinsic view is taken to build the self-representation in the local area of the tangent space at each Grassmannian point, resulting in a localized LRR method on Grassmann manifold. A novel algorithm for solving the proposed model is investigated and implemented. The performance of the new clustering algorithm is assessed through experiments on several real-world data sets including MNIST handwritten digits, ballet video clips, SKIG action clips, and DynTex++ data set and highway traffic video clips. The experimental results show that the new method outperforms a number of state-of-the-art clustering methods. [ABSTRACT FROM AUTHOR]

Traditional synthesis/analysis sparse representation models signals in a one dimensional (1D) way, in which a multidimensional (MD) signal is converted into a 1D vector. 1D modeling cannot sufficiently handle MD signals of high dimensionality in limited computational resources and memory usage, as breaking the data structure and inherently ignores the diversity of MD signals (tensors). We utilize the multilinearity of tensors to establish the redundant basis of the space of multi linear maps with the sparsity constraint, and further propose MD synthesis/analysis sparse models to effectively and efficiently represent MD signals in their original form. The dimensional features of MD signals are captured by a series of dictionaries simultaneously and collaboratively. The corresponding dictionary learning algorithms and unified MD signal restoration formulations are proposed. The effectiveness of the proposed models and dictionary learning algorithms is demonstrated through experiments on MD signals denoising, image super-resolution and texture classification. Experiments show that the proposed MD models outperform state-of-the-art 1D models in terms of signal representation quality, computational overhead, and memory storage. Moreover, our proposed MD sparse models generalize the 1D sparse models and are flexible and adaptive to both homogeneous and inhomogeneous properties of MD signals. [ABSTRACT FROM AUTHOR]

In multicamera video surveillance, it is challenging to represent videos from different cameras properly and fuse them efficiently for specific applications such as human activity recognition and clustering. In this paper, a novel representation for multicamera video data, namely, the product Grassmann manifold (PGM), is proposed to model video sequences as points on the Grassmann manifold and integrate them as a whole in the product manifold form. In addition, with a new geometry metric on the product manifold, the conventional low rank representation (LRR) model is extended onto PGM and the new LRR model can be used for clustering nonlinear data, such as multicamera video data. To evaluate the proposed method, a number of clustering experiments are conducted on several multicamera video data sets of human activity, including the Dongzhimen Transport Hub Crowd action data set, the ACT 42 Human Action data set, and the SKIG action data set. The experiment results show that the proposed method outperforms many state-of-the-art clustering methods. [ABSTRACT FROM PUBLISHER]

Many application scenarios involve sequential data, but most existing clustering methods do not well utilize the order information embedded in sequential data. In this paper, we study the subspace clustering problem for sequential data and propose a new clustering method, namely ordered sparse clustering with block-diagonal prior (BD-OSC). Instead of using the sparse normalizer in existing sparse subspace clustering methods, a quadratic normalizer for the data sparse representation is adopted to model the correlation among the data sparse coefficients. Additionally, a block-diagonal prior for the spectral clustering affinity matrix is integrated with the model to improve clustering accuracy. To solve the proposed BD-OSC model, which is a complex optimization problem with quadratic normalizer and block-diagonal prior constraint, an efficient algorithm is proposed. We test the proposed clustering method on several types of databases, such as synthetic subspace data set, human face database, video scene clips, motion tracks, and dynamic 3-D face expression sequences. The experiments show that the proposed method outperforms state-of-the-art subspace clustering methods. [ABSTRACT FROM PUBLISHER]