It is challenging for crowd counting models to generalize to new scenes due to domain shifts in training and test data. Although domain adaptation approaches have made notable progress in bridging the domain gap, they require target domain data. In this paper, we propose a novel framework for cross-scene crowd counting, which unifies domain generalization and adaptation. For domain generalization, we train a model only using single-domain data and the model can be generalized to any scene with satisfying performance. Regarding domain adaptation, we use both source and target domain data to further improve the performance. We first design a generation network that diversifies the generated samples to cover the unseen target domains as much as possible by minimizing mutual information. This approach simulates training data in various domains, thereby enhancing the model's generalization ability. Then we develop a pixel-wise supervised contrastive loss function that pulls the human heads in the source images and generated images closer to each other and pushes them further away from the background. This loss helps extract a domain-invariant feature representation, thus improving the model's generalization ability. Moreover, if information about the target domain is available, our generalization method can be easily applied as an adaptation method by replacing the mutual information minimization loss with the mutual information maximization loss. This can further improve cross-scene crowd counting performance. The experimental results demonstrate the strong generalizability of our method across different datasets.

Applying existing vehicle re-identification methods directly to the re-identification task of E-bikes comes with high costs for capturing and annotating a specific dataset, and it is prone to missing small E-bikes in dense street scenes. In this paper, an innovative E-bikes re-identification system (E-reID) is proposed to address the challenge of E-bikes re-identification for dense small packed object in complex street scenes with only need for a small detection dataset of E-bikes. This system decomposes the task of re-identification for small E-bikes in complex backgrounds into two sub-tasks: instance segmentation and instance retrieval. The instance segmentation is composed of a specific object detection branch that trained with the custom detection dataset to avoid missing the small E-bikes and a MASK branch trained with publicly available datasets containing similar objects such as motorcars and bicycles. For the instance retrieval task, this paper tested methods such as SIFT matching and HSV histogram for matching the same E-bike in different scenarios. The E-reID system built in this paper demonstrates good performance in the custom re-identification dataset of E-bikes. This paper provides an effective and cost-efficient solution to the re-identification of small-target E-bikes in complex scenes.

Existing local dynamic route planning algorithms, when directly applied to terrain following/terrain avoidance, or dynamic obstacle avoidance for large and medium-sized fixed-wing aircraft, fail to simultaneously meet the requirements of real-time performance, long-distance planning, and the dynamic constraints of large and medium-sized aircraft. To deal with this issue, this paper proposes the Motion Dynamic RRT based Fluid Field - PPO for dynamic TF/TA routing planning. Firstly, the action and state spaces of the proximal policy gradient algorithm are redesigned using disturbance flow fields and artificial potential field algorithms, establishing an aircraft dynamics model, and designing a state transition process based on this model. Additionally, a reward function is designed to encourage strategies for obstacle avoidance, terrain following, terrain avoidance, and safe flight. Experimental results on real DEM data demonstrate that our algorithm can complete long-distance flight tasks through collision-free trajectory planning that complies with dynamic constraints, without the need for prior global planning.

Predicting the trajectory of pedestrians in crowd scenarios is indispensable in self-driving or autonomous mobile robot field because estimating the future locations of pedestrians around is beneficial for policy decision to avoid collision. It is a challenging issue because humans have different walking motions, and the interactions between humans and objects in the current environment, especially between humans themselves, are complex. Previous researchers focused on how to model human-human interactions but neglected the relative importance of interactions. To address this issue, a novel mechanism based on correntropy is introduced. The proposed mechanism not only can measure the relative importance of human-human interactions but also can build personal space for each pedestrian. An interaction module, including this data-driven mechanism, is further proposed. In the proposed module, the data-driven mechanism can effectively extract the feature representations of dynamic human-human interactions in the scene and calculate the corresponding weights to represent the importance of different interactions. To share such social messages among pedestrians, an interaction-aware architecture based on long short-term memory network for trajectory prediction is designed. Experiments are conducted on two public datasets. Experimental results demonstrate that our model can achieve better performance than several latest methods with good performance.

Crowd counting models in highly congested areas confront two main challenges: weak localization ability and difficulty in differentiating between foreground and background, leading to inaccurate estimations. The reason is that objects in highly congested areas are normally small and high-level features extracted by convolutional neural networks are less discriminative to represent small objects. To address these problems, we propose a learning discriminative features framework for crowd counting, which is composed of a masked feature prediction module (MPM) and a supervised pixel-level contrastive learning module (CLM). The MPM randomly masks feature vectors in the feature map and then reconstructs them, allowing the model to learn about what is present in the masked regions and improving the model's ability to localize objects in high-density regions. The CLM pulls targets close to each other and pushes them far away from background in the feature space, enabling the model to discriminate foreground objects from background. Additionally, the proposed modules can be beneficial in various computer vision tasks, such as crowd counting and object detection, where dense scenes or cluttered environments pose challenges to accurate localization. The proposed two modules are plug-and-play, incorporating the proposed modules into existing models can potentially boost their performance in these scenarios.

With the development of data acquisition technology, RGB color information is widely collected to strengthen the 3D point cloud. To some extent, RGB color information contains the prior relation about the spatial position of objects. However, the existing point cloud segmentation networks based on deep learning do not pay much attention to it. To remedy the lack in this area, we propose a color-difference correntropy guided convolution network, which introduces correntropy to optimize the measurement of color-difference. Meanwhile, we select points in the local neighborhood via the color-difference guided module, and construct an ordered sequence of points with correlation information, which not only facilitates the feature extraction by directly applying the convolution but also fully studies the correlation between the color information and spatial position of the point cloud. Moreover, we fuse the sequence features extracted by convolution with the geometric features acquired by MLP to get new features with more abundant semantic information, thus improving the segmentation performance. On both indoor and outdoor datasets, the experimental results demonstrate the effectiveness and superiority of the proposed method by the comparison experiments and ablation experiments.

In the field of video self-supervised learning, contrastive instance learning methods suffer from a lack of semantic information, resulting in inadequate generalization in downstream tasks. Although optical flow can provide some semantic information, it requires significant computational cost prior to training. To address this, we propose a Video self-supervised Cross-pathway training model based on Slow and Fast pathways (VCSF). This model separately extracts temporal and spatial features from pure RGB video frames, and uses the complementary representations of the two pathways to conduct cross-pathway training. Additionally, we propose a motion perception module in the low-frame-rate space to enhance the network's ability to perceive rapidly changing human motion. We conducted extensive experiments in downstream missions of UCF101 and HMDB51, and obtained state-of-the-art results in models using the UCF101 data set for self-supervised pre-training, including motion recognition and nearest neighbor retrieval.

In real-world crowd counting applications, the crowd densities in an image vary greatly. When facing density variation, humans tend to locate and count the targets in low-density regions, and reason the number in high-density regions. We observe that CNN focus on the local information correlation using a fixed-size convolution kernel and the Transformer could effectively extract the semantic crowd information by using the global self-attention mechanism. Thus, CNN could locate and estimate crowds accurately in low-density regions, while it is hard to properly perceive the densities in high-density regions. On the contrary, Transformer has a high reliability in high-density regions, but fails to locate the targets in sparse regions. Neither CNN nor Transformer can well deal with this kind of density variation. To address this problem, we propose a CNN and Transformer Adaptive Selection Network (CTASNet) which can adaptively select the appropriate counting branch for different density regions. Firstly, CTASNet generates the prediction results of CNN and Transformer. Then, considering that CNN/Transformer is appropriate for low/high-density regions, a density guided adaptive selection module is designed to automatically combine the predictions of CNN and Transformer. Moreover, to reduce the influences of annotation noise, we introduce a Correntropy based optimal transport loss. Extensive experiments on four challenging crowd counting datasets have validated the proposed method.

Counting objects in crowded scenes remains a challenge to computer vision. The current deep learning based approach often formulate it as a Gaussian density regression problem. Such a brute-force regression, though effective, may not consider the annotation displacement properly which arises from the human annotation process and may lead to different distributions. We conjecture that it would be beneficial to consider the annotation displacement in the dense object counting task. To obtain strong robustness against annotation displacement, generalized Gaussian distribution (GGD) function with a tunable bandwidth and shape parameter is exploited to form the learning target point annotation probability map, PAPM. Specifically, we first present a hand-designed PAPM method (HD-PAPM), in which we design a function based on GGD to tolerate the annotation displacement. For end-to-end training, the hand-designed PAPM may not be optimal for the particular network and dataset. An adaptively learned PAPM method (AL-PAPM) is proposed. To improve the robustness to annotation displacement, we design an effective transport cost function based on GGD. The proposed PAPM is capable of integration with other methods. We also combine PAPM with P2PNet through modifying the matching cost matrix, forming P2P-PAPM. This could also improve the robustness to annotation displacement of P2PNet. Extensive experiments show the superiority of our proposed methods.

Bone age, as a measure of biological age (BA), plays an important role in a variety of fields, including forensics, orthodontics, sports, and immigration. Despite its significance, accurate estimation of BA remains a challenge due to the uncertainty error between BA and chronological age (CA) caused by individual diversity and the difficult integration of multiple factors, such as sex, and identified or measured anatomical structures, into the estimation process. To address problems, we propose an uncertainty-aware and sex-prior guided biological age estimation from orthopantomogram images (OPGs), named UASP-BAE, which models uncertainty errors while setting sex dimorphism as tractive features to enhance age-related specific features, aiming to improve the accuracy of BA estimation. Furthermore, considering the global relevance of the anatomic structure, such as the mandible, teeth, maxillary sinus, etc., a cross-attention module based on CNN and self-attention is proposed to mine the local texture and global semantic features of OPGs. Moreover, we design a novel age composition loss by cross-entropy, probability bias, and regression functions, aiming at evaluating BA's uncertainty errors and results to obtain an accurate and robust model. On 10703 OPGs from 5.00 to 25.00 years of age, our model had a best MAE value of 0.8005 years and higher than the comparison popular algorithms, which also demonstrates the method's potential for improved accuracy in BA estimation.

Predicting air quality in fine spatiotemporal granularity is of great importance for air pollution control and urban sustainability. However, existing studies are either focused on predicting station-wise future air quality, or inferring current air quality for unmonitored regions. How to accurately forecast future air quality for these unmonitored regions in a fine granularity remains an unexplored problem. In this paper, we propose the Self-Supervised Hierarchical Graph Neural Network (SSH-GNN), for fine-grained air quality forecasting in a semi-supervised way. Specifically, to augment spatially sparse air quality observations, SSH-GNN first approximates the city-wide air quality distribution based on historical readings and various urban contextual factors (e.g., weather conditions and traffic flows). Then, we propose a hierarchical recurrent graph neural network to make city-wide predictions, which encodes the spatial hierarchy of urban regions for long-range spatiotemporal correlation modeling. Moreover, by leveraging spatiotemporal self-supervision strategies, SSH-GNN exploits both universal topological and contextual patterns to further enhance the forecasting effectiveness. Extensive experiments on two real-world datasets show that SSH-GNN significantly outperforms the state-of-the-art algorithms.

In this paper, we propose a deep weight global registration (DWG-Reg) algorithm for poor initialization and partially overlapping point clouds registration problem. Our DWG-Reg is based on three modules: a bidirectional nearest search strategy for correspondence, a convolutional network for correspondence confidence prediction which consists of Hybird Distance Generator, optimal annealing Parameter Prediction network and a robust kernel function, a weighted optimizer algorithm for closed-form pose estimation. Experimental results show that our DWG-Reg achieves state-of-the-art performance compared to existing non-deep learning and recent deep learning methods. Our source code will open at https://github.com/BiaoBiaoLi/DWG-Reg.

Pedestrian trajectory prediction is an important but difficult task in self-driving or autonomous mobile robot field because there are complex unpredictable human-human interactions in crowded scenarios. There have been a large number of studies that attempt to understand humans' social behavior. However, most of these studies extract location features from previous one time step while neglecting the vital velocity features. In order to address this issue, we propose a novel feature-cascaded framework for long short-term network (CF-LSTM) without extra artificial settings or social rules. In this framework, feature information from previous two time steps are firstly extracted and then integrated as a cascaded feature to LSTM, which is able to capture the previous location information and dynamic velocity information, simultaneously. In addition, this scene-agnostic cascaded feature is the external manifestation of complex human-human interactions, which can also effectively capture dynamic interaction information in different scenes without any other pedestrians' information. Experiments on public benchmark datasets indicate that our model achieves better performance than the state-of-the-art methods and this feature-cascaded framework has the ability to implicitly learn human-human interactions.

In this study, the authors present a novel individual retrieval method based on oral cavity point cloud data and correntropy‐based registration algorithm. Since the three‐dimensional oral cavity data contains a large amount of noise and outliers, it may lead to a decrease in registration accuracy, which affects the accuracy of retrieval rate. Therefore, the authors introduce the correntropy into the rigid registration algorithm to solve this problem. Then, they filter the matched point cloud data and then use the mean squared error to judge the individual differences of the model data. Finally, the accurate retrieval of the oral cavity data is realised. Experimental results demonstrate the proposed retrieval three‐dimensional model algorithm can be successfully searched under different model data, which can help forensics use the characteristics of biological individuals to accurately search and identify, and improve recognition efficiency.

In this paper, noted by the regular geometric structure of indoor scene, a biased down-sampling scheme is designed to automatically adjust the local sampling rate according to the local density and distribution. Our down-sampling results can effectively remain the main structure while greatly reduce the data number for the following work. Moreover, an improved Iterative Closest Point (ICP) algorithm for point clouds registration is proposed with the prior of structure information. Sampled structured data is weighted to give their contributions for registration. This leads the parameter estimation to naturally focus on aligning the structures of indoor scenes. The experimental results demonstrate the effectiveness of the proposed method on improving the registration accuracy with the same level of down-sampling data.

The aim of trajectory planning is to generate a feasible, collision-free trajectory to guide an autonomous vehicle from the initial state to the goal state safely. However, it is difficult to guarantee that the trajectory is feasible for the vehicle and the real path of the vehicle is collision-free when the vehicle follows the trajectory. In this paper, a state-increment statistical model (SISM) is proposed to describe the kinodynamic constraints of a vehicle by modeling the controller, the actuator, and the vehicle model jointly. The SISM consists of Gaussian distributions of lateral error increments in all state subspaces which are composed of the curvature radius, the velocity, and the lateral error. It is a data-driven modeling approach that can improve the SISM via increasing the number of samples of the increment-state, which is composed of the state and its corresponding increment of the lateral error. According to the SISM, the experience cost functions are designed to evaluate the trajectories for searching the best one with the lowest cost, and the real path can be predicted directly according to the planned trajectory and the vehicle state. The predicted path can be utilized effectually to evaluate the safety of the vehicle motion.

Owing to their universal approximation capability and online learning manner, kernel adaptive filters have been widely used in nonlinear systems modeling. Under Gaussian assumption, traditional kernel adaptive algorithms utilize the well-known mean square error(MSE) as a cost function to get optimal solutions. For non-Gaussian situations, MSE will not properly represent the statistics of the error, and hence degrade the performance. In recent years, an information theoretic learning(ITL) based criterion called Maximum Correntropy Criterion(MCC) has been proposed and applied in robust adaptive filtering. The correntropy is a generalized correlation measure in kernel space, which uses Gaussian kernel as a default kernel function. Of course, Gaussian kernel is not always the best choice. Recently, a more flexible definition of correntropy, called generalized correntropy, has been proposed. With a proper shape parameter, the generalized correntropy may get better performance than original correntropy with Gaussian kernel. In this paper, we take advantages of both kernel methods and generalized correntropy to develop a new kernel adaptive algorithm called Generalized Kernel Maximum Correntropy(GKMC) algorithm. We analyze theoretically the stability and steady-state performance of the new algorithm. In addition, we propose a Quantized GKMC(QGKMC) algorithm to curb the growth of the network size in GKMC while maintaining the performance. Simulation results confirm the theoretical expectations and show superior performance compared with existing methods.

This paper proposes an obstacle avoidance method for navigation of a mobile robot in uncertain environments based on a novel neural learning algorithm, namely least mean p-norm extreme learning machine (LMP-ELM) and Q-learning. The proposed obstacle avoidance method comprises of two behavior modules, Viz., an avoidance behavior and goal-seeking behavior. At the learning phase, the two modules are independently designed using the proposed LMP-ELM and Q-Learning. And then they are combined to navigate the mobile to the goal position without colliding with obstacles based on a switching function at the running phase. The LMP-ELM is used to realize the state-action mapping of the Q-learning. In the novel LMP-ELM, the computationally simple extreme learning machine architecture is maintained but a novel error criterion, namely the least mean p-power (LMP) error criterion provides a mechanism to update the output weights sequentially. The LMP error criterion aims to minimize the mean p-power of the error that is the generalization of the mean square error criterion used in the ELM. The effectiveness of the proposed method is verified by a series of simulations.

A novel scheme for diagnosing sensor failures in a flight control system is presented. In the proposed scheme, a set of self-organizing fuzzy systems named as SAFISs are applied as the online approximators for recognizing the sensor outputs in order to determine the failure detection, identification and accommodation (FDIA). SAFIS is an online learning fuzzy system with concurrent structure and parameter learning. The rules of the SAFIS are added or deleted based on the input data without predefining them by trial and error. The efficiency of the proposed scheme is demonstrated by simulation examples where soft failures in the angular rate gyros are successfully diagnosed.

In the traditional trajectory planning methods, a feasible, collision-free trajectory is generated to guide the vehicle. But generally the vehicle cannot follow the trajectory without tracking deviation because of the vehicle kinematical constraints and the performance of control algorithm. In this paper, State-Statistical Model (SSM) based trajectory-band planning method is proposed to predict the vehicle motion during the vehicle tracks the trajectory. In this method, the statistics of historical states are used to build the SSM which is a normal distribution model of tracking deviation in different segments of curvature radius and velocity. According to the SSM, the inaccessible states of vehicle can be obtained to search the best trajectory and the tracking deviation boundary can be calculated on the trajectory. Then the best trajectory is used as the base line to generate the trajectory-band of which the halfband width is the deviation boundary value. As a result, the trajectory-band can represent the maximum range of vehicle motion accurately.