Adversarial attack strategies for 3D object detection have highlighted the critical importance of addressing security concerns in this domain. However, white-box methods require full access to the victim model in large-scale point cloud applications. To this end, we propose a novel Policy-Driven Black-box Attack (BAT) that is designed to optimize attack locations without necessitating detailed knowledge of the victim models. First, we introduce a density-aware pattern generator that creates scene-adaptive attack clusters. Second, we leverage the deep deterministic policy gradient in deep reinforcement learning to train an attack agent capable of targeting the victim model. Ultimately, the attack agent is iteratively directed towards optimal attack locations through the joint application of critic loss and actor loss. To the best of our knowledge, this represents the first reinforcement learning-based black-box attack applied to practical 3D object detection. Experimental results on the KITTI, nuScenes, and Waymo datasets demonstrate that BAT effectively diminishes the accuracy of notable models. Importantly, BAT significantly enhances the attack success rate (surpassing state-of-the-art both white-box and black-box methods) and increases transferability (by 20 times) through simple deep deterministic policy gradient, thus establishing a new baseline for adversarial attacks in 3D object detection.

Centralized Traffic Engineering (TE) plays a critical role in network management, owing to its potential to achieve optimal or near-optimal network performance. However, the overhead from frequent network-wide traffic measurements required to observe the global network view significantly limits its practical use. To address this issue, we propose an end-to-end learning approach called TEST for routing optimization using sparse Traffic Matrices (TMs) obtained from sparse traffic measurements, which require measuring traffic on only a subset of network nodes. Specifically, to mitigate the impact of unknown traffic demands in unmeasured nodes on network performance, we construct a set of synthesized TMs with diverse traffic patterns adaptively to enhance the robustness of the generated routing policies. To address the missed information in sparsely measured TMs, we leverage historical sparse TM sequences to provide sufficient evidence for generating routing policies. To effectively capture the spatio-temporal relationships in the sparse TM sequence, we propose designing a routing model by integrating a Transformer model with a Graph Convolutional Network (GCN). Extensive experiments conducted on topologies with different scales demonstrate that the proposed TEST achieves promising TE performance under sparse traffic measurements. Additionally, discussions on scenarios involving network failures and traffic changes further highlight its robustness.

Quantum networks, leveraging the principles of quantum mechanics, enable unconditionally secure communication and are emerging as a critical component of next-generation infrastructure. However, the scarcity of quantum network resources results in contention among requests for shared links and qubits. Such contention prolongs processing times and degrades resource utilization efficiency, which in turn leads to imbalanced completion times between high- and low-priority requests. This paper addresses the request scheduling problem by proposing DRL-QN, a scheduling framework based on Reinforcement Learning (RL) that optimizes scheduling sequences, reduces the completion time of network requests, and improves fairness. Specifically, to help the agent better perceive request contention and the network environment, request characteristics and network resources are described as the state, enabling accurate scheduling decisions. Furthermore, to ensure a balanced learning objective, the agent’s training is guided by a multi-objective reward function that simultaneously promotes low completion time and fairness. Extensive simulations demonstrate that the proposed DRL-QN method significantly reduces network completion time by 16.22%–21.25% compared with existing schemes, while achieving fairness comparable to the fairness-optimal method and improving by approximately 6.79%–13.61% over other approaches.

Routing optimization, as a significant part of Traffic Engineering (TE), plays an important role in balancing network traffic and improving quality of service . With the application of Machine Learning (ML) in various fields, many neural network-based routing optimization solutions have been proposed. However, most existing ML-based methods need to retrain the model when confronted with a network unseen during training, which incurs significant time overhead and response delay. To improve the generalization ability of the routing model, in this paper, we innovatively propose a routing optimization method GROM which combines Deep Reinforcement Learning (DRL) and Graph Neural Networks (GNN), to directly generate routing policies under different and unseen network topologies without retraining. Specifically, for handling different network topologies , we transform the traffic-splitting ratio into element-level output of GNN model . To make the DRL agent easier to converge and well generalize to unseen topologies, we discretize the huge continuous traffic-splitting action space. Extensive simulation results on five real-world network topologies demonstrate that GROM can rapidly generate routing policies under different network topologies and has superior generalization ability.

Traffic Engineering (TE) is an efficient technique to balance network flows and thus improves the performance of a hybrid Software Defined Network (SDN). Previous TE solutions mainly leverage heuristic algorithms to centrally optimize link weight setting or traffic splitting ratios under the static traffic demand. Note that as the network scale becomes larger and network management gains more complexity, it is notably that the centralized TE methods suffer from a high computation overhead and a long reaction time to optimize routing of flows when the network traffic demand dynamically fluctuates or network failures happen. To enable adaptive and efficient routing in distributed TE, we propose a Multi-agent Reinforcement Learning method CMRL that divides the routing optimization of a large network into multiple small-scale routing decision-making problems. To coordinate the multiple agents for achieving a global optimization goal in a hybrid SDN scenario, we construct a reasonable virtual environment to meet different routing constraints brought by legacy routers and SDN switches for training the routing agents. To train the routing agents for determining the local routing policies according to local network observations, we introduce the difference reward assignment mechanism for encouraging agents to cooperatively take optimal routing action. Extensive simulations conducted on the real traffic traces demonstrate the superiority of CMRL in improving TE performance, especially when traffic demands change or network failures happen.

Point clouds semantic labeling is an important task in 3D computer vision. Current major researches focus on fully supervised learning. However, point-by-point manual annotations are expensive and time-consuming. To this end, we propose a general point clouds deep active learning framework to ease the annotation burden for researchers. In this work, we propose a conditional random field (CRF) based pseudo labels generation to provide more supervised information for deep neural network (DNN) and employ Golden Loss Correction (GLC) to correct pseudo labeled data training loss. Finally, we propose the Modified Margin acquisition function which can select the most valuable points for labeling. We demonstrate the improvements provided by our proposed method on the S3DIS benchmark.

Recently, laser scanning system is widely used to accurately predict forest inventory attributes. In this work, we propose an efficient framework including Feature Extractor Module and Conditional Adversarial Module for object classification in 3D heterogeneous point clouds. The Feature Extractor Module can aggregate features of objects in point clouds. For domain adaptation task, the Conditional Adversarial Module is proposed to minimize the discrepancy of source and target domains. Since there is no common evaluation benchmark for object classification in 3D point cloud, we build a bench-mark of six tasks from three 3D objects datasets. Evaluations on six tasks with four categories have demonstrated the effectiveness of our proposed framework of object classification. The framework can be applied potentially in forest management.

Nowadays, researchers have developed various deep neural networks for processing point clouds effectively. Due to the enormous parameters in deep learning-based models, a lot of manual efforts have to be invested into annotating sufficient training samples. To mitigate such manual efforts of annotating samples for a new scanning device, this letter focuses on proposing a new neural network to achieve domain adaptation in 3D object classification. Specifically, to minimize the data discrepancy of intra-class objects in different domains, an Asymmetrical Siamese module is designed to align the intra-class features. To preserve the discriminative information for distinguishing inter-class objects in different domains, a Conditional Adversarial module is leveraged to consider the classification information conveyed from the classifier. To verify the effectiveness of the proposed method on object classification in heterogeneous point clouds, evaluations are conducted on three point cloud datasets, which are collected in different scenarios by different laser scanning devices. Furthermore, the comparative experiments also demonstrate the superior performance of the proposed method on the classification accuracy.

Feature matching is a fundamental problem in feature-based remote sensing image registration. Due to the ground relief variations and imaging viewpoint changes, remote sensing images often involve local distortions, leading to difficulties in high-accuracy image registration. To address this issue, in this article, we propose a robust feature matching method called First Neighbor Relation Guided (FNRG) for remote sensing image registration via guided hyperplane fitting. The key idea of FNRG is to exploit the first neighbor relation of feature points between two images for seeking consistent seeds in a parameter-free manner. To boost more consistent matches based on the consistent seeds, we formulate the feature matching problem into an affine hyperplane fitting problem by imposing the motion consistency, and then we design a hyperplane updating strategy to refine the fitting model. We also introduce a locality preserving structure-based cost function to promote the matching performance of the hyperplane updating strategy. Our method can mine consistent matches from thousands of putative ones within only a few milliseconds, and it also can handle the data with a large-scale change, rotation, or severe nonrigid deformation. Extensive experiments on the remote sensing image data sets with different types of image transformations show that the proposed method achieves significant superiority over several state-of-the-art methods.

Scene understanding in 3-D point clouds requires to annotate points manually at the model training stage. To reduce manual efforts in labeling points, this letter focuses on proposing an efficient method to implement semiautomatic segmentation of 3-D objects in 3-D point clouds. Specifically, to handle point clouds with high point density, supervoxels are treated as basic operating units during the object segmentation procedure. To obtain the valuable boundaries for guiding 3-D object segmentation, we propose to filter meaningless boundaries obtained by a traditional boundary detection method. Once valuable boundaries are obtained, we propose a boundary-aware Markov random field (MRF) model to consider the object-boundary constraint into generating the boundary-preserved segmentation results. Extensive experiments on two data sets show the effectiveness of our proposed framework on segmenting 3-D objects from point cloud scenes.

Recently, 3D deep learning technologies require a large amount of supervised 3D point-cloud data to learn statistical models for various ITS-related tasks, e.g. object classification, object detection, object segmentation, etc. However, manually annotating 3D point-cloud data is time-consuming and labor-intensive. Therefore, this paper aims at co-locating 3D objects from mobile LiDAR point clouds without any help of supervised training data. To realize it, we propose a new framework to implement 3D object co-localization for automatically extracting the objects of the same category from different point-cloud scenes. Specifically, to search and exploit the co-information from objects in different point-cloud scenes, we formulate a 3D object co-localization problem as a maximal subgraph matching problem. During the graph construction procedure, to handle the inconsistent representation of objects in different scenes, we propose a multi-scale clustering method to represent objects by a pyramid structure. In addition, because the maximal subgraph matching problem is NP-hard, we propose a stochastic search algorithm to generate the co-localization results. Extensive experiments on the point-cloud data collected by the Reigl VMX450 mobile LiDAR system demonstrate the promising performance of the proposed framework.

Object classification model used in point clouds requires to be retrained when applying on heterogeneous point clouds that are collected from different kinds of laser scanning systems. The model training procedure needs supervised information from the corresponding laser scanning systems. However, the acquisition of supervised information is labor-intensive and time-consuming. This letter proposes a new framework to exploit objects from point clouds with supervised information (source domain) to directly classify objects from heterogeneous point clouds with no supervised information (target domain). More specifically, to alleviate occlusions and point density variations, intraclass variations in object classification, the proposed framework integrates a bag-of-words model to effectively describe 3-D objects of point clouds. To alleviate the difference of point clouds collected from various devices, a joint distribution adaption model is exploited to build an effective feature transformation to accomplish the adaption in the source and target domains. The proposed framework is validated on data sets, which contain three kinds of point clouds. Extensive experiments show the effectiveness of the proposed framework on classifying 3-D objects in heterogeneous point clouds.

Using mobile Light Detection and Ranging point clouds to accomplish road scene labeling tasks shows promise for a variety of applications. Most existing methods for semantic labeling of point clouds require a huge number of fully supervised point cloud scenes, where each point needs to be manually annotated with a specific category. Manually annotating each point in point cloud scenes is labor intensive and hinders practical usage of those methods. To alleviate such a huge burden of manual annotation, in this paper, we introduce an active learning method that avoids annotating the whole point cloud scenes by iteratively annotating a small portion of unlabeled supervoxels and creating a minimal manually annotated training set. In order to avoid the biased sampling existing in traditional active learning methods, a neighbor-consistency prior is exploited to select the potentially misclassified samples into the training set to improve the accuracy of the statistical model. Furthermore, lots of methods only consider short-range contextual information to conduct semantic labeling tasks, but ignore the long-range contexts among local variables. In this paper, we use a higher order Markov random field model to take into account more contexts for refining the labeling results, despite of lacking fully supervised scenes. Evaluations on three data sets show that our proposed framework achieves a high accuracy in labeling point clouds although only a small portion of labels is provided. Moreover, comparative experiments demonstrate that our proposed framework is superior to traditional sampling methods and exhibits comparable performance to those fully supervised models.

Effective extraction of road boundaries plays a significant role in intelligent transportation applications, including autonomous driving, vehicle navigation, and mapping. This paper presents a new method to automatically extract 3-D road boundaries from mobile laser scanning (MLS) data. The proposed method includes two main stages: supervoxel generation and 3-D road boundary extraction. Supervoxels are generated by selecting smooth points as seeds and assigning points into facets centered on these seeds using several attributes (e.g., geometric, intensity, and spatial distance). 3-D road boundaries are then extracted using the α-shape algorithm and the graph cuts-based energy minimization algorithm. The proposed method was tested on two data sets acquired by a RIEGL VMX-450 MLS system. Experimental results show that road boundaries can be robustly extracted with an average completeness over 95%, an average correctness over 98%, and an average quality over 94% on two data sets. The effectiveness and superiority of the proposed method over the state-of-the-art methods is demonstrated.

Automatic annotation of 3D objects in cluttered scenes shows its great importance to a variety of applications. Nowadays, 3D point clouds, a new 3D representation of real-world objects, can be easily and rapidly collected by mobile LiDAR systems, e.g. RIEGL VMX-450 system. Moreover, the mobile LiDAR system can also provide a series of consecutive multi-view images which are calibrated with 3D point clouds. This paper proposes to automatically annotate 3D objects of interest in point clouds of road scenes by exploiting a multitude of annotated images in image databases, such as LabelMe and ImageNet. In the proposed method, an object detector trained on the annotated images is used to locate the object regions in acquired multi-view images. Then, based on the correspondences between multi-view images and 3D point clouds, a probabilistic graphical model is used to model the temporal, spatial and geometric constraints to extract the 3D objects automatically. A new dataset was built for evaluation and the experimental results demonstrate a satisfied performance on 3D object extraction.

This paper proposes a novel approach for traffic sign detection and rapid damage inspection in natural scenes based on mobile laser scanning (MLS) data, including images and point clouds. The inspection results assist traffic management departments to take immediate measures to update and maintain traffic signs after natural disasters leading to many damaged traffic signs. Our approach involves four steps: Firstly, we use a deep learning network, Fast regions with convolutional neural network (Fast R-CNN), to train a traffic sign detector in an open benchmark, where the images are more variable and have a higher resolution. Then, traffic signs in images are detected by using the trained detector. Next, the area of the traffic sign, based on the sign area in the image, is roughly detected in MLS point clouds. Then, an accurate traffic sign is detected. Finally, some placement parameters of the traffic sign are measured for damage inspection and further inventory. Our proposed approach is validated on a set of point-clouds acquired by a RIEGL VMX-450 MLS system. Experimental results demonstrate that the rapidity and reliability of our proposed approach in traffic sign detection and damage inspection are robust.

For survey and maintenance of traffic signs, this paper presents a novel traffic sign occlusion detection method using 3-D point clouds and trajectory data acquired by a mobile laser scanning system. To produce a maintenance guide, our method aims to obtain the degree of occlusion by analyzing the spatial relationship between traffic signs, surroundings, and drivers on the road. First, a detection method considering both reflectance and geometric features is developed to capture traffic signs. Next, to simulate the driver's view, a trajectory-based method is proposed to determine driver's observation location and the corresponding observed traffic sign. Finally, to determine whether a traffic sign is in occlusion, a hidden point removal algorithm is adopted and carried out. Furthermore, we develop two indices to evaluate the degree of occlusion. The proposed method is tested using two point cloud data sets collected by an RIEGL VMX-450 system along a 23.68-km-long urban road. The obtained results illustrate the feasibility of the proposed occlusion detection method.

With rapid development of light detection and ranging (LiDAR) technologies, three dimensional point clouds increasingly become a new approach to sense the world. In our previous work, light poles were detected from mobile LiDAR point clouds without using their locations. In this paper, we improve our previous work by considering location information between two neighboring light poles to reduce false alarm. In the proposed method, the potential light poles are first detected by the extended Hough Forest Framework. Then, a gaussian distribution is exploited to model the distance between two light poles by using locations of those detected light poles. Finally, inaccurately detected light poles are removed by considering the distance between two adjacent objects. We evaluate our proposed method on mobile LiDAR point clouds acquired by RIEGL VMX-450 system. On the basis of the experimental test instances, we demonstrate improved accuracy on light pole detection.

This paper presents a new algorithm to directly extract 3D road boundaries from mobile laser scanning (MLS) point clouds. The algorithm includes two stages: 1) non-ground point removal by a voxel-based elevation filter, and 2) 3D road surface extraction by curb-line detection based on energy minimization and graph cuts. The proposed algorithm was tested on a dataset acquired by a RIEGL VMX-450 MLS system. The results fully demonstrate the effectiveness and superiority of the proposed algorithm.

This paper presents a study of vehicle detection from high-resolution aerial images. In this paper, a superpixel segmentation method designed for aerial images is proposed to control the segmentation with a low breakage rate. To make the training and detection more efficient, we extract meaningful patches based on the centers of the segmented superpixels. After the segmentation, through a training sample selection iteration strategy that is based on the sparse representation, we obtain a complete and small training subset from the original entire training set. With the selected training subset, we obtain a dictionary with high discrimination ability for vehicle detection. During training and detection, the grids of histogram of oriented gradient descriptor are used for feature extraction. To further improve the training and detection efficiency, a method is proposed for the defined main direction estimation of each patch. By rotating each patch to its main direction, we give the patches consistent directions. Comprehensive analyses and comparisons on two data sets illustrate the satisfactory performance of the proposed algorithm.

This paper presents an algorithm for vehicle detection in high-resolution aerial images through a fast sparse representation classification method and a multiorder feature descriptor that contains information of texture, color, and high-order context. To speed up computation of sparse representation, a set of small dictionaries, instead of a large dictionary containing all training items, is used for classification. To extract the context information of a patch, we proposed a high-order context information extraction method based on the proposed fast sparse representation classification method. To effectively extract the color information, the RGB color space is transformed into color name space. Then, the color name information is embedded into the grids of histogram of oriented gradient feature to represent the low-order feature of vehicles. By combining low- and high-order features together, a multiorder feature is used to describe vehicles. We also proposed a sample selection strategy based on our fast sparse representation classification method to construct a complete training subset. Finally, a set of dictionaries, which are trained by the multiorder features of the selected training subset, is used to detect vehicles based on superpixel segmentation results of aerial images. Experimental results illustrate the satisfactory performance of our algorithm.

Semantic labeling of road scenes using colorized mobile LiDAR point clouds is of great significance in a variety of applications, particularly intelligent transportation systems. However, many challenges, such as incompleteness of objects caused by occlusion, overlapping between neighboring objects, interclass local similarities, and computational burden brought by a huge number of points, make it an ongoing open research area. In this paper, we propose a novel patch-based framework for labeling road scenes of colorized mobile LiDAR point clouds. In the proposed framework, first, three-dimensional (3-D) patches extracted from point clouds are used to construct a 3-D patch-based match graph structure (3D-PMG), which transfers category labels from labeled to unlabeled point cloud road scenes efficiently. Then, to rectify the transferring errors caused by local patch similarities in different categories, contextual information among 3-D patches is exploited by combining 3D-PMG with Markov random fields. In the experiments, the proposed framework is validated on colorized mobile LiDAR point clouds acquired by the RIEGL VMX-450 mobile LiDAR system. Comparative experiments show the superior performance of the proposed framework for accurate semantic labeling of road scenes.

This paper presents a spatial-related traffic sign inspection process for sign type, position, and placement using mobile laser scanning (MLS) data acquired by a RIEGL VMX-450 system and presents its potential for traffic sign inventory applications. First, the paper describes an algorithm for traffic sign detection in complicated road scenes based on the retroreflectivity properties of traffic signs in MLS point clouds. Then, a point cloud-to-image registration process is proposed to project the traffic sign point clouds onto a 2-D image plane. Third, based on the extracted traffic sign points, we propose a traffic sign position and placement inspection process by creating geospatial relations between the traffic signs and road environment. For further inventory applications, we acquire several spatial-related inventory measurements. Finally, a traffic sign recognition process is conducted to assign sign type. With the acquired sign type, position, and placement data, a spatial-associated sign network is built. Experimental results indicate satisfactory performance of the proposed detection, recognition, position, and placement inspection algorithms. The experimental results also prove the potential of MLS data for automatic traffic sign inventory applications.

This paper presents a novel method for traffic sign detection and visibility evaluation from mobile Light Detection and Ranging (LiDAR) point clouds and the corresponding images. Our algorithm involves two steps. Firstly, a detection algorithm based on high retro-reflectivity of the traffic sign from the MLS point clouds is designed for sign detection in complicated road scenes. To solve the spatial features of traffic signs, we also create geo-referenced relations between traffic signs and roads according to the normal of ground. Secondly, we propose a visibility estimation method to evaluate the visibility level of the traffic sign based on a combination of visual appearance and spatial-related features. The proposed algorithm is validated on a set of transportation-related point-clouds acquired by a RIEGL VMX-450 LiDAR system. The experiment results demonstrate that the efficiency and reliability of the proposed algorithm in detection traffic signs are robust, and also prove the potential of using mobile LiDAR data for traffic sign visibility evaluation.

The accurate extraction of roads is a prerequisite for the automatic extraction of other road features. This letter describes a method for detecting road boundaries from mobile laser scanning (MLS) point clouds in an urban environment. The key idea of our method is directly constructing a saliency map on 3-D unorganized point clouds to extract road boundaries. The method consists of four major steps, i.e., road partition with the assistance of the vehicle trajectory, salient map construction and salient points extraction, curb detection and curb lowest points extraction, and road boundaries fitting. The performance of the proposed method is evaluated on the point clouds of an urban scene collected by a RIEGL VMX-450 MLS system. The completeness, correctness, and quality of the extracted road boundaries are 95.41%, 99.35%, and 94.81%, respectively. Experimental results demonstrate that our method is feasible for detecting road boundaries in MLS point clouds.

This letter presents a novel rotation-invariant method for object detection from terrestrial 3-D laser scanning point clouds acquired in complex urban environments. We utilize the Implicit Shape Model to describe object categories, and extend the Hough Forest framework for object detection in 3-D point clouds. A 3-D local patch is described by structure and reflectance features and then mapped to the probabilistic vote about the possible location of the object center. Objects are detected at the peak points in the 3-D Hough voting space. To deal with the arbitrary azimuths of objects in real world, circular voting strategy is introduced by rotating the offset vector. To deal with the interference of adjacent objects, distance weighted voting is proposed. Large-scale real-world point cloud data collected by terrestrial mobile laser scanning systems are used to evaluate the performance. Experimental results demonstrate that the proposed method outperforms the state-of-the-art 3-D object detection methods.