Due to the complex visual environment, such as lighting variations, shadows, and limitations of vision, the accuracy of vacant parking slot detection for the park assist system (PAS) with a standalone around view monitor (AVM) needs to be improved. To address this problem, we propose a vacant parking slot detection method based on deep learning, namely VPS-Net. VPS-Net converts the vacant parking slot detection into a two-step problem, including parking slot detection and occupancy classification. In the parking slot detection stage, we propose a parking slot detection method based on YOLOv3, which combines the classification of the parking slot with the localization of marking points so that various parking slots can be directly inferred using geometric cues. In the occupancy classification stage, we design a customized network whose size of convolution kernel and number of layers are adjusted according to the characteristics of the parking slot. Experiments show that VPS-Net can detect various vacant parking slots with a precision rate of 99.63% and a recall rate of 99.31% in the ps2.0 dataset, and has a satisfying generalizability in the PSV dataset. By introducing a multi-object detection network and a classification network, VPS-Net can detect various vacant parking slots robustly.

The around view monitor system (AVM) has been widely used in passenger vehicles. However, for articulated engineering vehicles (AEV), AVM is difficult to directly apply due to the long body and the articulation angle. In this paper, a flexible technique for variable-angle around view monitor system (VAVM) towards the AEV is proposed, which includes static calibration and dynamic execution. In the static calibration stage, the camera poses in the vehicle coordinate system with the joint of AEV as the coordinate origin can be calibrated using irregularly placed multiple checkerboards without knowing their relative position. This flexible calibration approach makes the variable-angle mapping from the fisheye image to the bird’s eye view image can be directly obtained by updating the camera poses on the tractor according to the articulation angle when the AEV turns. In the dynamic execution stage, an optimization algorithm based on minimizing the photometric error is designed to reduce the cumulative error of the angle sensor. Finally, all the bird’s eye view images are mosaiced and fused to a variable-angle around view image (VAVI). The experimental results show that the VAVM can output globally balanced and seamless VAVIs under different angles and visual environment conditions. Furthermore, the practicability of VAVM is also demonstrated by a real AEV.

Due to distortion, limitations of vision, and occlusion, most of the existing vacant parking slot detection methods with a standalone around view monitor (AVM) are prone to miss some parking slots and incorrectly identify whether the parking slot is vacant. To overcome this problem, we propose a complete method for vacant parking slot detection and tracking during driving and parking. Considering the different conditions of driving and parking, two different deep convolutional neural networks (DCNNs) are used to detect parking slots, of which the vacant parking slot detection network (VPS-Net) is used to detect vacant parking slots during driving, and the directional marking point detection network (DMPR-PS) is used to detect the directional marking points of the target parking slot during parking. Furthermore, in the driving process, we design a new matching rule and tracking management rule based on the Kernelized Correlation Filter (KCF) to track the parking slots, and fuse classification results of multiple frames to determine the occupancy status. In the parking process, since the parking slot is easily blocked by the vehicle, we design another new tracker to track the directional marking points and infer the complete parking slot using tracking results and prior geometric information. To evaluate the proposed method, a labeled video sequence dataset is established. Experiments show that the proposed method has improved the accuracy and continuity of vacant parking slots detection and positioning whether in the driving process or parking process.

Linear feature extraction is crucial for special objects in semantic segmentation networks, such as slot marking and lanes. The objects with linear characteristics have global contextual information dependency. It is very difficult to capture the complete information of these objects in semantic segmentation tasks. To improve the linear feature extraction ability of the semantic segmentation network, we propose introducing the dilated convolution with vertical and horizontal kernels (DVH) into the task of feature extraction in semantic segmentation networks. Meanwhile, we figure out the outcome if we put the different vertical and horizontal kernels on different places in the semantic segmentation networks. Our networks are trained on the basis of the SS dataset, the TuSimple lane dataset and the Massachusetts Roads dataset. These datasets consist of slot marking, lanes, and road images. The research results show that our method improves the accuracy of the slot marking segmentation of the SS dataset by 2%. Compared with other state-of-the-art methods, our UnetDVH-Linear (v1) obtains better accuracy on the TuSimple Benchmark Lane Detection Challenge with a value of 97.53%. To prove the generalization of our models, road segmentation experiments were performed on aerial images. Without data argumentation, the segmentation accuracy of our model on the Massachusetts roads dataset is 95.3%. Moreover, our models perform better than other models when training with the same loss function and experimental settings. The experiment result shows that the dilated convolution with vertical and horizontal kernels will enhance the neural network on linear feature extraction.

In the background of hierarchical diagnosis and treatment, the problems of two-way referral have attracted considerable attention in recent years. Most research of two-way referral mainly focuses on the qualitative research on the operation mechanism and the management mode, but there arefew considerations of decision making method for two-way referral. In this paper, we use stochastic multicriteria acceptability analysis-2 (SMAA-2) to solve the problem of uncertainties of indicator values and weights in two-sided matching decision-making for two-way referral.

The ViBe (Visual Background extractor) algorithm is a moving object detection algorithm, which has good adaptability and real-time performance. Although its performance is excellent, the ViBe algorithm also has some disadvantages, such as easy to introduce ghost, insensitive to the detection of static targets, and easy to detect the shadow area as the foreground. In order to improve its performance, various improved ViBe algorithms emerged recently. In this paper, we firstly introduce the ViBe algorithm in detail, including background modeling, foreground detection and background model updating; Secondly, we introduce and analyze the improved algorithms to address its each shortcoming and to enhance the robustness in time order; Finally, we summarize and prospect the improved ViBe algorithms.