Multi-view clustering (MVC) with bipartite graph has been extensively studied to rapidly handle multi-source heterogeneous information via sparse anchors. However, most existing methods follow a two-stage learning paradigm that first learns continuous label matrix and then discretizes it, not only bringing extra trade-off parameters but yielding suboptimal solutions. Also, numerous methods still exhibit limited scalability for large-scale problems. Thus, this paper proposes two novel models for discrete, trade-off parameter-free and rapid MVC. First, the Bipartite Graph Discrete Reconstruction (BGDR) model uniquely leverages the discrete label matrices of both samples and anchors to dynamically reconstruct a consensus bipartite graph across views. This concise reconstruction style eliminates redundant computations, and anchor labels enable to enrich cluster partition information during reconstruction, enhancing both accuracy and efficiency. The final clustering outcomes are directly acquired via discrete sample labels. Second, to free the optimization time overheads from the limitation of sample size, we further devise the Compact Graph Discrete Reconstruction (CGDR) model, which reconstructs a smaller compact affinity graph among anchors for significant acceleration. Original sample labels are then gained by label propagation. Systematic experiments illuminate that both models reach superior outcomes in term of efficacy and efficiency.

Multiview clustering aims to detect the consistent graph structure across each view, and has garnered extensive attention in recent years. However, the graph quality determines the clustering performance and cannot be updated in most methods, while the label extraction also relies on post-processing (e.g. spectral rotation). As a consequence, multiple objective functions are optimized independently, making it difficult to achieve one-pass clustering. Motivated by this, Graph-Free Multiview Clustering with Anchor (GMCA) is proposed towards coherence (in optimization), simplicity (in hyperparameters). Considering that similarity only exist among samples in the same cluster for ideal assignments, a label-based reverse framework is proposed for the first time to achieve feature approximation via graph-free factorization. Although non-negative label matrix exhibits indicative interpretability, cluster independence is overlooked, thus non-negative and orthogonal constraint is further imposed and proved beneficial for ideal graph backtracking. Besides, to prevent optimization from focusing on extreme approximating loss caused by redundant features, the Frobenius norm is employed, while allocating flexible view weights as collateral benefit. Comparison experiments with fourteen state-of-the-art methods are performed on eight real-world data sets, while our method exceeds the second-best method by up to$4.85\%$in clustering accuracy and keeps running time linear with samples number.

This paper introduces a Gaussian-enhanced multi-agent reinforcement learning framework for developing scalable evasion strategies in dynamic pursuit scenarios. The proposed methodology addresses two critical challenges in unknown environments: sparse reward structures and local optima convergence, while enhancing escape feasibility through probabilistic decision-making. By integrating Gaussian process regression with Q-function approximation, the framework enables efficient online parameter adaptation and demonstrates improved sample efficiency in high-dimensional state spaces. Comprehensive simulations and physical experiments across terrestrial and aerial robotic platforms validate the framework’s effectiveness and robustness in complex evasion tasks. The architecture’s modular design permits generalization to multi-agent pursuit-evasion scenarios with variable participant numbers, establishing a versatile foundation for strategic interactions in large-scale autonomous systems.

Fuzzy clustering and its derivatives have been widely applied for handling overlapping clusters through probabilistic membership assignment, yet their performance degrades under cumulative outlier interference. To cope with this limitation, we propose the Outlier Resistant Fuzzy Clustering via Row Sparse Discriminative Embedding Projection (RFCDE), which introduces an adaptive sample contribution vector to resist the outliers, a row-sparse membership refinement strategy to enhance normal sample attention, and a projection-guided prototype learning module to mitigate representation bias. Furthermore, a discriminative embedding objective is designed to effectively mitigate extraneous feature effects. These modules form a unified iterative architecture that improves clustering reliability in a low-dimensional framework. Comparative experiments on real-world datasets validate its broad applicability.

Graph-based clustering technique has garnered significant attention due to precise information characterization by pairwise graph similarity. Nevertheless, the post-processing step in traditional methods often limits clustering effects because of crucial information loss. Therefore, the Constrained Laplacian Rank (CLR) theory emerges to directly obtain discrete labels from optimally structural graph, achieving desirable outcomes. However, CLR suffers from substantial time overhead, making it infeasible for large-scale data analysis. To overcome this issue, we propose Anchor-based CLR (ACLR), a simple yet effective method for efficient large-scale clustering. The ACLR method comprises four stages: (1) anchors that roughly cover original data are opted to prepare bipartite graph construction; (2) a novel two-step probability transition (TSPT) strategy initializes a small-scale graph with random walk probability among anchors; (3) the main ACLR model alternately optimizes the graph connected structure and directly produces discrete anchor labels, achieving a time complexity independent of the number of samples due to dramatically reduced graph scale; and (4) labels are propagated from anchors to samples using$K$-NN algorithm. Extensive experiments demonstrate that ACLR yields superior accuracy and efficiency, particularly when applied to large-scale data. The codes are available athttps://github.com/MarathonZhenyuMa/2025-TKDE-ACLR.

Video inpainting aims to complete missing frames visually convincingly by balancing high-frequency detailed textures and low-frequency semantic structures. Conventional approaches utilize generative adversarial and reconstruction losses for optimizing output frames, each favoring different frequency aspects, to achieve this equilibrium. However, employing both loss types concurrently often results in a conflict between perceptual and distortion qualities, mainly due to their distinct frequency preferences. In response, this letter introduces the Waveletbased Transformer network for Video Inpainting (WTVI). WTVI employs a 2D discrete wavelet transform (DWT) to decompose frames into various frequency bands, ensuring the preservation of spatial information. It then independently completes missing regions in each band using Transformer network. To mitigate inter-frequency conflicts, we apply reconstruction loss to the low-frequency bands and adversarial loss to the high-frequency bzands. Additionally, we innovate High-frequency Cross-Attention (HCA) and Low-frequency Cross-Attention (LCA) modules to enhance frequency dependency learning beyond the spatialtemporal scope and to align features across bands. Our experiments confirm that WTVI surpasses previous methods, significantly improving both quantitative and qualitative performance.

Recently, anchor-based strategy is getting a lot of attention, which extends spectral clustering to reveal the dual relation between samples and features. However, the acquisition of clustering results follows the relaxed-discrete procedure, which might lead to serious information loss. Given that, local-global fuzzy clustering with anchor graph is proposed in this article, which jointly completes subspace learning and clustering. With the construction of anchor graph, we first impose the fuzzy constraint on the indicator matrix, which is beneficial for revealing the ambiguity and uncertainty in clustering tasks. Thereafter, we introduce the graph divergence regularization term for maximizing the variance of fuzzy indicator matrix, which not only avoids the trivial solutions in local graph learning, but also enhances the separability of data for explicit global structure. In this way, the local graph loss and global divergence regularization term are able to jointly capture the critical clustering structure. Finally, we can obtain the clustering results in accordance with the optimal fuzzy indicator matrix, which is updated alternately by the presented coordinate descent method in optimization process. Therefore, the desirable discrete labels come out automatically under the fuzzy strategy without extra discretization operations, which conforms to reality. The effectiveness of our method will be demonstrated through comprehensive experimental results.

The unsupervised nature of clustering has attracted significant interest. In particular, researchers delve into exploring the superiority of fuzzy clustering in flexibly handling computations involving uncertain data. However, outliers can present considerable challenges by distorting the measurement of similarity between samples, and biases in projection subspace learning may impede accurate partitioning. In this article, we propose a robust discriminant embedding projection fuzzy clustering with optimal mean (RPFCOM) method. First, the weighted loss function term distinguishes outliers and normal samples through boolean weight, thereby inducing row sparsity in the learning of projection subspace. The distribution of boolean weight penalizes outliers with large errors in the projection subspace. Second, we incorporate minimizing projection reconstruction information learning while suppressing redundant features, where the optimal mean dynamically corrects the projection learning bias. And the embedding of discriminative information further strengthens the capability of differentiating normal samples. Finally, the proposed method adaptively updates the boolean weight to identify outliers, which joints fuzzy membership matrix constructed from the maximum entropy graphs, enhancing the stability in distinguishing normal sample clusters. Comprehensive experimental validation on noise contaminated dataset has demonstrated the superiority of RPFCOM.

Embedded feature selection approach guides subsequent projection matrix (selection matrix) learning through the acquisition of pseudolabel matrix to conduct feature selection tasks. Yet the continuous pseudolabel matrix learned from relaxed problem based on spectral analysis deviates from reality to some extent. To cope with this issue, we design an efficient feature selection framework inspired by classical least-squares regression (LSR) and discriminative K-means (DisK-means), which is called the fast sparse discriminative K-means (FSDK) for the feature selection method. First, the weighted pseudolabel matrix with discrete trait is introduced to avoid trivial solution from unsupervised LSR. On this condition, any constraint imposed into pseudolabel matrix and selection matrix is dispensable, which is significantly beneficial to simplify the combinational optimization problem. Second, the$\ell_{2,p}$-norm regularizer is introduced to satisfy the row sparsity of selection matrix with flexible$p$. Consequently, the proposed FSDK model can be treated as a novel feature selection framework integrated from the DisK-means algorithm and$\ell_{2,p}$-norm regularizer to optimize the sparse regression problem. Moreover, our model is linearly correlated with the number of samples, which is speedy to handle the large-scale data. Comprehensive tests on various data terminally illuminate the effectiveness and efficiency of FSDK.

Spectral clustering (SC) has been applied to analyze varieties of data structures over the past few decades owing to its outstanding breakthrough in graph learning. However, the time-consuming eigenvalue decomposition (EVD) and information loss during relaxation and discretization impact the efficiency and accuracy especially for large-scale data. To address above issues, this brief proposes a simple and fast method named efficient discrete clustering with anchor graph (EDCAG) to circumvent postprocessing by binary label optimization. First of all, sparse anchors are adopted to accelerate graph construction and obtain a parameter-free anchor similarity matrix. Subsequently, inspired by intraclass similarity maximization in SC, we design an intraclass similarity maximization model between anchor-sample layer to cope with anchor graph cut problem and exploit more explicit data structures. Meanwhile, a fast coordinate rising (CR) algorithm is employed to alternatively optimize discrete labels of samples and anchors in designed model. Experimental results show excellent rapidity and competitive clustering effect of EDCAG.

As a simple yet effective method, least squares regression (LSR) is extensively applied for data regression and classification. Combined with sparse representation, LSR can be extended to feature selection (FS) as well, in which$\ell_{1}$regularization is often applied in embedded FS algorithms. However, because the loss function is in the form of squared error, LSR and its variants are sensitive to noises, which significantly degrades the effectiveness and performance of classification and FS. To cope with the problem, we propose a generalized and robust LSR (GRLSR) for classification and FS, which is made up of arbitrary concave loss function and the$\ell_{2,p}$-norm regularization term. Meanwhile, an iterative algorithm is applied to efficiently deal with the nonconvex minimization problem, in which an additional weight to suppress the effect of noises is added to each data point. The weights can be automatically assigned according to the error of the samples. When the error is large, the value of the corresponding weight is small. It is this mechanism that allows GRLSR to reduce the impact of noises and outliers. According to the different formulations of the concave loss function, four specific methods are proposed to clarify the essence of the framework. Comprehensive experiments on corrupted datasets have proven the advantage of the proposed method.

In the past few years, visual tracking methods with convolution neural networks (CNNs) have gained great popularity and success. However, the convolution operation of CNNs struggles to relate spatially distant information, which limits the discriminative power of trackers. Very recently, several Transformer-assisted tracking approaches have emerged to alleviate the above issue by combining CNNs with Transformers to enhance the feature representation. In contrast to the methods mentioned above, this article explores a pure Transformer-based model with a novel semi-Siamese architecture. Both the time-space self-attention module used to construct the feature extraction backbone and the cross-attention discriminator used to estimate the response map solely leverage attention without convolution. Inspired by the recent vision transformers (ViTs), we propose the multistage alternating time-space Transformers (ATSTs) to learn robust feature representation. Specifically, temporal and spatial tokens at each stage are alternately extracted and encoded by separate Transformers. Subsequently, a cross-attention discriminator is proposed to directly generate response maps of the search region without additional prediction heads or correlation filters. Experimental results show that our ATST-based model attains favorable results against state-of-the-art convolutional trackers. Moreover, it shows comparable performance with recent "CNN + Transformer" trackers on various benchmarks while our ATST requires significantly less training data.

Feature selection and feature extraction, in the field of data dimensionality reduction, are the two main strategies. Nevertheless, each of these two strategies has its own advantages and disadvantages. The features chosen by feature selection method have complete physical meaning. However, feature selection cannot reveal the implicit structural information of the samples. In this article, the methods proposed by us combine both feature selection and feature extraction, called joint feature selection and extraction with sparse unsupervised projection (SUP) and graph optimization SUP (GOSUP). A constraint on the number of nonzero rows of the projection matrix is added, which ensures the sparsity of the projection matrix, and only the features corresponding to the nonzero rows of the projection matrix are selected for the feature extraction procedure. We invoke a newly proposed algorithm to tackle this constrained optimization problem. A new concept of "purification matrix" is invented, the use of which could better eliminate meaningless information of samples in subspace. The performance on several datasets verifies the effectiveness of the proposed method for data dimensionality reduction.

Least squares regression (LSR) is widely applied in statistics theory due to its theoretical solution, which can be used in supervised, semisupervised, and multiclass learning. However, LSR begins to fail and its discriminative ability cannot be guaranteed when the original data have been corrupted and noised. In reality, the noises are unavoidable and could greatly affect the error construction in LSR. To cope with this problem, a robust supervised LSR (RSLSR) is proposed to eliminate the effect of noises and outliers. The loss function adopts$\ell _{2,p}$-norm ($0< p\leq 2$) instead of square loss. In addition, the probability weight is added to each sample to determine whether the sample is a normal point or not. Its physical meaning is very clear, in which if the point is normal, the probability value is 1; otherwise, the weight is 0. To effectively solve the concave problem, an iterative algorithm is introduced, in which additional weights are added to penalize normal samples with large errors. We also extend RSLSR to robust semisupervised LSR (RSSLSR) to fully utilize the limited labeled samples. A large number of classification performances on corrupted data illustrate the robustness of the proposed methods.

Anomaly detection (AD) on hyperspectral images has been widely researched in recent decades due to its high practicability and wide range of application scenarios. Such AD methods derived from low-rank matrix decomposition (LRMD) have appeared rapidly and been applied effectively. However, most of them focused on the use of spectral information and neglected the abundant spatial characteristics. In this letter, a spectral-spatial total variation (TV) (SSTV) regularized low-rank matrix decomposition method with a Schatten 1/2 quasi-norm ($S_{1/2}$) and denoising is proposed. First, to exploit the hyperspectral imagery (HSI) characteristics from the spectral perspective, we propose the low-rank matrix decomposition method with$S_{1/2}$norm and image denoising modules. Second, we incorporate the SSTV regularization by employing a 2-D TV (TV) spatially and 1-D TV along the spectral dimension to realize the maximized utilization of spatial characteristics of HSI. Finally, the alternating direction multiplier method (ADMM) is brought in the calculating process to attain the consequent detection results. The superiority of the proposed method has been demonstrated by the excellent performance on three real datasets.

Anomaly detection has been drawing a great deal of attention by virtue of its practicability among the hyperspectral research area. Low-rank representation (LRR) has been widely employed to detect anomalies from hyperspectral imagery (HSI) effectively while a great number of methods derived from LRR replace rank function with a nuclear norm, which gives rise to a certain amount of error. In this letter, we propose a Schatten 1/2 quasi-norm ($S_{1/2}$) regularized LRR (SRLRR) method with an improved algorithm of establishing the dictionary for hyperspectral anomaly detection. First,$S_{1/2}$regularization is proposed to substitute the initial nuclear norm to approximate the rank function. Second, an improved dictionary construction algorithm based on K-Means++ clustering is presented to integrate the model and improve the performance. Finally, the optimization algorithm through alternating direction multiplier method (ADMM) incorporating a half threshold operator is introduced to attain the eventual results. Our method has been testified on three typical data sets and demonstrates the eminent performance.

Hyperspectral images can provide spectral characteristics related to the physical properties of different materials, which arouses great interest in many fields. Band selection (BS) could effectively solve the problem of high dimensions and redundant information of HSI data. However, most BS methods utilize a single measurement criterion to evaluate band importance so that the assessment of bands is not comprehensive. To dispose of these issues, we propose the hypergraph spectral clustering band selection (HSCBS) method in this letter. First, a novel hypergraph construction method is proposed to combine bands selected by different priority criteria. Second, based on the hypergraph Laplacian matrix, an unsupervised band selection model named HSCBS is presented to cluster the bands into compact clusters with high within-class similarity and low between-class similarity. The results of comprehensive experimental on two public real datasets demonstrate the effectiveness of HSCBS.

As a significant and fundamental task in the remote sensing field, object detection has received increasing attention and research studies. However, geospatial object detection is still a challenge owing to the dramatic variation in object scales, intraclass differences, and interclass similarity from multiscale and multiclass objects. To deal with these problems, an end-to-end feature-reflowing pyramid network (FRPNet) is proposed in this letter. FRPNet has two advantages that contribute to improve object detection accuracy. First, we embed a nonlocal block into the backbone in order to get the relevancy between different regions of the geospatial image for obtaining discriminative features. Furthermore, a feature-reflowing pyramid structure is proposed to generate high-quality feature presentation for each scale through fusing fine-grained features from the adjacent lower level, which improves the detection capability for multiscale and multiclass objects. Experiments on a public remote sensing data set DIOR illustrate that FRPNet can significantly improve the performance when compared to several state-of-the-art detection approaches in terms of mean average precision (mAP).

Unlike object detection in natural images that usually achieved great success, remote sensing imagery has its own challenges to detect and localize multiclass objects, such as large-scale change, uncertain direction, and high density. The context information of the objects is very worthwhile for solving these challenges in remote sensing images. In this letter, we propose a context-driven detection network (CDD-Net) to improve the accuracy of multiclass object detection in remote sensing images. For capturing the local neighboring objects and features, a local context feature network (LCFN) is proposed to learn the local context of the region of interest. Meanwhile, a hybrid attention pyramid network (HAPN) is designed, which can steer the focus to more valuable features. The HAPN inserts a squeeze and excitation block (SEB) and three asymmetric convolution blocks (ACBs) in the feature pyramid network (FPN). The experimental results over the DOTA-v1.5 data set demonstrate that the proposed CDD-Net yields promising results.

Unmanned Aerial Vehicle (UAV) Videos have received active research attention in the remote sensing field by taking full advantage of the bird’s eye view offered by UAV. At the same time, visual tracking approaches based on discriminative correlation filters (DCF) have recently achieved increasing popularity and success. Despite their success, the tracking robustness and accuracy of existing DCF-based trackers are hard to promote in challenging tracking scenarios of aerial videos due to excessive reliance on the response map and fixed linear model update strategy. To resolve these issues, we propose a robust DCF-based tracking framework via an effective pretrained rectification network for UAV-based remote sensing. Specifically, the target-specific rectification network is offline trained to discriminatively classify the target and background. During the online tracking stage, the DCF module performs fast inference to obtain the potential locations of the target. After that, the deep rectification network evaluates the correlation-specific proposals offered by the DCF module and provides precise tracking results. Besides, to achieve a robust and adaptive model update strategy, we propose to finetune both the DCF module and rectification network according to the classification confidence of the estimated result. Extensive experimental results on recent UAV benchmarks demonstrate that our method achieves better performance than other competing algorithms.

Compared with general optical images, remote sensing images (RSIs) capture large areas from high altitudes with a bird’s eye view, which is responsible for the many categories and scale variations of objects in the images, as well as the abundant scene information. Although the complexity of the RSIs presents a significant challenge to the object detection task, the complexity presents opportunities as well. The RSIs contain plenty of object-related context information, which is valuable for boosting the object detection performance. To address the existing issue of poor context utilization in RSIs, we propose a hierarchical context embedding network (HCENet) in this letter. First, we construct a semantic feature pyramid, in which the semantic context aggregation module (SFAM) integrates the semantic contexts included in the adjacent layers of features with a novel feature fusion mechanism. Furthermore, the scene-level context embedding module (SLCEM) extracts the scene context of the overall image by a simple design and is utilized to guide feature classification. Finally, we outperform the popular object detectors on the publicly available DOTA-v1.5 dataset, achieving superior performance.

Accurate object detection in remote sensing images is an essential part of automatic extraction, analysis, and understanding of image information, which potentially plays a significant role in a number of practical applications. However, the scale diversity in remote sensing images presents a substantial challenge for object detection, regarded as one of the crucial problems to be solved. To extract multiscale feature representations and sufficiently exploit semantic context information, this letter proposes a semantic context-aware network (SCANet) model for multiscale object detection. We propose two novel modules, called receptive field-enhancement module (RFEM) and semantic context fusion module (SCFM), to enhance the performance of SCANet. The RFEM dedicates to more robust multiscale feature extraction by paying attention to distinct receptive fields through multibranch different convolutions. For the purpose of utilizing the semantic context information contained in the scene to guide the network to better detection accuracy, the SCFM integrates the semantic context features from the upper level with the lower level features and delivers them hierarchically. Experiments demonstrate that, compared with the state-of-the-art approaches, the SCANet yields superior detection results on the DOTA-v1.5 data set.

Dimension reduction is a critical technology for high-dimensional data processing, where Linear Discriminant Analysis (LDA) and its variants are effective supervised methods. However, LDA prefers to feature with smaller variance, which causes feature with weak discriminative ability retained. In this paper, we propose a novel Ratio Sum for Linear Discriminant Analysis (RSLDA), which aims at maximizing discriminative ability of each feature in subspace. To be specific, it maximizes the sum of ratio of the between-class distance to the within-class distance in each dimension of subspace. Since the original RSLDA problem is difficult to obtain the closed solution, an equivalent problem is developed which can be solved by an alternative optimization algorithm. For solving the equivalent problem, it is transformed into two sub-problems, one of which can be solved directly, the other is changed into a convex optimization problem, where singular value decomposition is employed instead of matrix inversion. Consequently, performance of algorithm cannot be affected by the non-singularity of covariance matrix. Furthermore, Kernel RSLDA (KRSLDA) is presented to improve the robustness of RSLDA. Additionally, time complexity of RSLDA and KRSLDA are analyzed. Extensive experiments show that RSLDA and KRSLDA outperforms other comparison methods on toy datasets and multiple public datasets.

Detecting moving objects from the video sequences has been treated as a challenging computer vision task, since the problems of dynamic background, multi-scale moving objects and various noise interference impact the corresponding feasibility and efficiency. In this paper, a novel spatio-temporal online matrix factorization (STOMF) method is proposed to detect multi-scale moving objects under dynamic background. To accommodate a wide range of the real noise distractions, we apply a specific mixture of exponential power (MoEP) distributions to the framework of low-rank matrix factorization (LRMF). For the optimization of solution algorithm, a temporal difference motion prior (TDMP) model is proposed, which estimates the motion matrix and calculates the weight matrix. Moreover, a partial spatial motion information (PSMI) post-processing method is further designed to implement multi-scale objects extraction in varieties of complex dynamic scenes, which utilizes partial background and motion information. The superiority of the STOMF method is validated by massive experiments on practical datasets, as compared with state-of-the-art moving objects detection approaches.

Multimodal emotion recognition in conversational videos (ERC) develops rapidly in recent years. To fully extract the relative context from video clips, most studies build their models on the entire dialogues which make them lack of real-time ERC ability. Different from related researches, a novel multimodal emotion recognition model for conversational videos based on reinforcement learning and domain knowledge (ERLDK) is proposed in this paper. In ERLDK, the reinforcement learning algorithm is introduced to conduct real-time ERC with the occurrence of conversations. The collection of history utterances is composed as an emotion-pair which represents the multimodal context of the following utterance to be recognized. Dueling deep-Q-network (DDQN) based on gated recurrent unit (GRU) layers is designed to learn the correct action from the alternative emotion categories. Domain knowledge is extracted from public dataset based on the former information of emotion-pairs. The extracted domain knowledge is used to revise the results from the RL module and is transformed into other dataset to examine the rationality. The experimental results on datasets show that ERLDK achieves the state-of-the-art results on weighted average and most of the specific emotion categories.

Visual tracking is a very critical issue in computer vision and video processing. For Discriminative Correlation Filter (DCF)-based tracking methods, it is very essential and meaningful to adaptively incorporate reliable target and surrounding information from video frames. However, most existing DCF-based trackers solely rely on pre-defined and fixed constraints such as a binary mask or quadratic function-based regularization to improve the discrimination. Unfortunately, such attempts fail to adjust the constraints according to the change of tracking circumstance in the video sequence, and thus lead to the lack of reliability of learned filters. To mitigate these problems, we present a novel DCF-based tracking method that introduces an adaptive target-and-surrounding soft mask (ATSM) into the learning formula. The adaptive soft mask that is represented by float numbers contains the detail information for both target region and its surrounding information: first, for the background area, it introduces meaningful background information and suppressing uninformative one; second, for the target area inside the bounding box, it helps to focus on the reliable area and repress the rapidly changing area; third, the target-and-surrounding soft mask is adaptively adjusted based on the variations of the target and its surrounding during the tracking process. By jointly modeling the filter and the adaptive soft mask, our ATSM tracker achieves an efficient integration of meaningful information of both foreground and background and performs favorably against state-of-the-art algorithms on seven well-known benchmarks.

These days, clustering is one of the most classical themes to analyze data structures in machine learning and pattern recognition. Recently, the anchor-based graph has been widely adopted to promote the clustering accuracy of plentiful graph-based clustering techniques. In order to achieve more satisfying clustering performance, we propose a novel clustering approach referred to as the progressive self-supervised clustering method with novel category discovery (PSSCNCD), which consists of three separate procedures specifically. First, we propose a new semisupervised framework with novel category discovery to guide label propagation processing, which is reinforced by the parameter-insensitive anchor-based graph obtained from balanced K -means and hierarchical K -means (BKHK). Second, we design a novel representative point selected strategy based on our semisupervised framework to discover each representative point and endow pseudolabel progressively, where every pseudolabel hypothetically corresponds to a real category in each self-supervised label propagation. Third, when sufficient representative points have been found, the labels of all samples will be finally predicted to obtain terminal clustering results. In addition, the experimental results on several toy examples and benchmark data sets comprehensively demonstrate that our method outperforms other clustering approaches.

Small aerial object detection plays an important role in numerous computer vision tasks, including remote sensing, early warning systems, and visual tracking. Despite existing moving object detection techniques that can achieve reasonable results in normal size objects, they fail to distinguish the small objects from the dynamic background. To cope with this issue, a novel method is proposed for accurate small aerial object detection under different situations. Initially, the block segmentation is introduced for reducing frame information redundancy. Meanwhile, a random projection feature (RPF) is proposed for characterizing blocks into feature vectors. Subsequently, a moving direction estimation based on feature vectors is presented to measure the motions of blocks and filter out the major directions. Finally, variable search region clustering (VSRC), together with the color feature difference, is designed for extracting pixelwise targets from the remaining moving direction blocks. The comprehensive experiments demonstrate that our approach outperforms the level of state-of-the-art methods upon the integrity of small aerial objects, especially on the dynamic background and scale variation targets.

With practical applications such as environment surveillance, agricultural production, and disaster assessment, accurate object detection in remote sensing images is in high demand. Precise detection of object instances in remote sensing images remains considerably challenging due to dense instance stacking, large-scale variations, and complex backgrounds. To solve the mentioned issues, a novel global context-weaving network (GCWNet) is developed for object detection in remote sensing images. We propose two novel modules for feature extraction and refinement, which include the global context aggregation module (GCAM) and the feature refinement module (FRM). GCAM assembles a global context with high-level and low-level features through feature weaving, which facilitates dense object detection. Meanwhile, FRM convolves multiple receptive fields by combining different branches, thereby further refining the features and improving the feature distinction at different scales. Furthermore, we design to alleviate the sample imbalanced problem during training using focal loss and balanced L1 loss to improve object classification and regression, respectively. The experimental results indicate that GCWNet achieves superior performance in object classification and localization on the DOTA-v1.5 dataset, which illustrates the superiority of GCWNet.

Benefit from avoiding the utilization of labeled samples, which are usually insufficient in the real world, unsupervised learning has been regarded as a speedy and powerful strategy on clustering tasks. However, clustering directly from primal data sets leads to high computational cost, which limits its application on large-scale and high-dimensional problems. Recently, anchor-based theories are proposed to partly mitigate this problem and field naturally sparse affinity matrix, while it is still a challenge to get excellent performance along with high efficiency. To dispose of this issue, we first presented a fast semisupervised framework (FSSF) combined with a balanced K -means-based hierarchical K -means (BKHK) method and the bipartite graph theory. Thereafter, we proposed a fast self-supervised clustering method involved in this crucial semisupervised framework, in which all labels are inferred from a constructed bipartite graph with exactly k connected components. The proposed method remarkably accelerates the general semisupervised learning through the anchor and consists of four significant parts: 1) obtaining the anchor set as interim through BKHK algorithm; 2) constructing the bipartite graph; 3) solving the self-supervised problem to construct a typical probability model with FSSF; and 4) selecting the most representative points regarding anchors from BKHK as an interim and conducting label propagation. The experimental results on toy examples and benchmark data sets have demonstrated that the proposed method outperforms other approaches.

Dimensionality reduction (DR) technique has been frequently used to alleviate information redundancy and reduce computational complexity. Traditional DR methods generally are inability to deal with nonlinear data and have high computational complexity. To cope with the problems, we propose a fast unsupervised projection (FUP) method. The simplified graph of FUP is constructed by samples and representative points, where the number of the representative points selected through iterative optimization is less than that of samples. By generating the presented graph, it is proved that large-scale data can be projected faster in numerous scenarios. Thereafter, the orthogonality FUP (OFUP) method is proposed to ensure the orthogonality of projection matrix. Specifically, the OFUP method is proved to be equivalent to PCA upon certain parameter setting. Experimental results on benchmark data sets show the effectiveness in retaining the essential information.

The linear discriminant analysis (LDA) method needs to be transformed into another form to acquire an approximate closed-form solution, which could lead to the error between the approximate solution and the true value. Furthermore, the sensitivity of dimensionality reduction (DR) methods to subspace dimensionality cannot be eliminated. In this article, a new formulation of trace ratio LDA (TRLDA) is proposed, which has an optimal solution of LDA. When solving the projection matrix, the TRLDA method given by us is transformed into a quadratic problem with regard to the Stiefel manifold. In addition, we propose a new trace difference problem named optimal dimensionality linear discriminant analysis (ODLDA) to determine the optimal subspace dimension. The nonmonotonicity of ODLDA guarantees the existence of optimal subspace dimensionality. Both the two approaches have achieved efficient DR on several data sets.

High-dimensional data are highly correlative and redundant, making it difficult to explore and analyze. Amount of unsupervised dimensionality reduction (DR) methods has been proposed, in which constructing a neighborhood graph is the primary step of DR methods. However, there exist two problems: 1) the construction of graph is usually separate from the selection of projection direction and 2) the original data are inevitably noisy. In this article, we propose an unsupervised adaptive embedding (UAE) method for DR to solve these challenges, which is a linear graph-embedding method. First, an adaptive allocation method of neighbors is proposed to construct the affinity graph. Second, the construction of affinity graph and calculation of projection matrix are integrated together. It considers the local relationship between samples and global characteristic of high-dimensional data, in which the cleaned data matrix is originally proposed to remove noise in subspace. The relationship between our method and local preserving projections (LPPs) is also explored. Finally, an alternative iteration optimization algorithm is derived to solve our model, the convergence and computational complexity of which are also analyzed. Comprehensive experiments on synthetic and benchmark datasets illustrate the superiority of our method.

Fusion of multimodal features is a momentous problem for video emotion recognition. As the development of deep learning, directly fusing feature matrixes of each mode through neural networks at feature level becomes mainstream method. However, unlike unimodal issues, for multimodal analysis, finding the correlations between different modal is as important as discovering effective unimodal features. To make up the deficiency in unearthing the intrinsic relationships between multimodal, a novel modularized multimodal emotion recognition model based on deep canonical correlation analysis (MERDCCA) is proposed in this letter. In MERDCCA, four utterances are gathered as a new group and each utterance contains text, audio and visual information as multimodal input. Gated recurrent unit layers are used to extract the unimodal features. Deep canonical correlation analysis based on encoder-decoder network is designed to extract cross-modal correlations by maximizing the relevance between multimodal. The experiments on two public datasets show that MERDCCA achieves the better results.

Discriminative correlation filters (DCF)-based trackers have been increasingly applied to visual tracking due to their high precision while running at high frame rates. However, most recent DCF-based methods solely concentrate on learning the correlation filter with spatial information and thus do not have sufficient descriptive power to discriminate the target from the background in the complex circumstances, such as full occlusion (OCC) and rapid target variation. In this article, we introduce a novel tracking framework that exploits the relationship between the target and its spatiotemporal context to improve tracking accuracy and robustness. Especially, we present our spatiotemporal context model in a hierarchical way, where each layer of the context pyramid is a spatial correlation filter learned from different temporal instances. For gaining an accurate spatiotemporal model, we propose an optimization fusion approach that can adaptively and efficiently learn the effect of each hierarchical layer and exploit these multiple temporal levels of correlation filters for visual tracking. Moreover, an adaptive model update strategy for correlation filters is introduced into the framework to dynamically select proper hierarchical layers, which boosts the temporal diversity of the target appearance, while radically reduces the number of model parameters and guarantees the real-time performance of the tracking method. The experimental results show that, with conventional handcrafted features, our tracker achieves the best success rates among available state-of-the-art trackers with handcrafted features, and provides state-of-the-art performance comparable to those of deep-learning-based trackers on OTB-2013, OTB-2015, VOT-2016, and UAV-20L benchmarks but runs significantly faster than deep trackers.

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In this letter, a novel morphological band selection method is proposed to obtain the most representative bands from hyperspectral image (HSI) in an unsupervised manner. In order to sufficiently process the HSI, we propose to use only a small set of data instead of using the original full data. For the obtained clusters, the differences of spectral response curves are applied to measure the local discrimination capability of bands, of which the local maximum value point is yielded based on the morphological processing. To verify the performance of the proposed method, the robustness of the parameters has been evaluated, while the effectiveness and superiority have been tested on three popular hyperspectral data sets. The experiment results have shown that the proposed method outperforms other methods.

In order to alleviate the negative effect of curse of dimensionality, band selection is a crucial step for hyperspectral image (HSI) processing. In this letter, we propose a novel unsupervised band selection approach to reduce the dimensionality for hyperspectral imagery. In order to obtain the most representative bands, the correlation matrix computed from the original HSI is used to describe the correlation characteristics among bands, while the block-diagonal structure is measured to segment all bands into a series of subspace. After applying the spectral clustering algorithm, the optimal combination of band is finally selected. To verify the effectiveness and superiority of the proposed band selection method, experiments have been conducted on three widely used real-world hyperspectral data. The results have shown that the proposed method outperforms other methods in HSI classification application.

The high-speed target interception plays a vital role in the modern industry with many application scenarios. Due to the difficulties of direct interception in high speed, the head pursuit intercept is frequently considered for the target of re-entering flight vehicle. In this paper, a novel terminal sliding mode control method is proposed for the interception of high-speed maneuvering target, in which the finite convergence guidance law is initially designed under the constraint of intercept angle. By introducing the mathematical model of correlative motion between interceptor and target, the sliding surface is researched and designed to meet the critical conditions of head pursuit intercepting. Meanwhile, considering the dynamic characteristics of both interceptor and target, an adaptive guidance law is therefore proposed to compensate the modelling errors, which goal is to improve the accuracy of interception. The stability analysis is theoretically proved in terms of the Lyapunov method. Numerical simulations are presented to validate the robustness and effectiveness of the proposed guidance law, by which good intercepting performance can be supported.

Artificial awareness is an interesting way of realizing artificial intelligent perception for machines. Since the foreground object can provide more useful information for perception and informative description of the environment than background regions, the informative saliency characteristics of the foreground object can be treated as a important cue of the objectness property. Thus, a sparse reconstruction error based detection approach is proposed in this paper. To be specific, the overcomplete dictionary is trained by using the image features derived from randomly selected background images, while the reconstruction error is computed in several scales to obtain better detection performance. Experiments on popular image dataset are conducted by applying the proposed approach, while comparison tests by using a state of the art visual saliency detection method are demonstrated as well. The experimental results have shown that the proposed approach is able to detect the foreground object which is distinct for awareness, and has better performance in detecting the information salient foreground object for artificial awareness than the state of the art visual saliency method.