Automated traffic incident detection with a smaller dataset based on generative adversarial networks.

An imbalanced and small training sample can cause an incident detection model to have a low detection rate and a high false alarm rate. To solve the scarcity of incident samples, a novel incident detection framework is proposed based on generative adversarial networks (GANs). First, spatial and temporal rules are presented to extract variables from traffic data, which is followed by the random forest algorithm to rank the importance of variables. Then, some new incident samples are generated using GANs. Finally, the support vector machine algorithm is applied as the incident detection model. Real traffic data, which were collected from a 69.5-mile section of the I-80 highway, are used to validate the proposed approach. A total of 140 detectors are installed on the section enabling traffic flow to be measured every 30s. During 14 days, 139 incident samples and 946 nonincident samples were extracted from the raw data. Five categories of experiments are designed to evaluate whether the proposed framework can solve the small sample size problem, imbalanced sample problem, and timeliness problem in the current incident detection system. The experimental results show that our proposed framework can considerably improve the detection rate and reduce the false alarm rate of traffic incident detection. The balance of the dataset can improve the detection rate from 87.48% to 90.68% and reduce the false alarm rate from 12.76% to 7.11%. This paper lends support to further studies on combining GANs with the machine learning model to address the imbalance and small sample size problems related to intelligent transportation systems.

Optical 3-D surface reconstruction with color binary speckle pattern encoding.

This paper proposes a novel 3-D surface profile measurement scheme by only a single-shot color binary speckle pattern (CBSP) and a temporal-spatial correlation matching algorithm, which can be applied to measurements of dynamic and static objects. R/G/B channels of CBSP are coupled with three carefully designed black and white binary speckle patterns (BWBSPs), whose physical features are associated with the system configuration parameters. We mathematically deduce the concrete details of how to design such a pattern and its relationship with the system parameters selected in the experiment. During 3-D reconstruction, we develop an extended temporal-spatial correlation framework to determine the correspondence between two stereo images sequences that are composed of R/G/B images separated from a captured color stereo image pair. Comparative experiments and analysis are implemented to assess the measurement accuracy using standard workpieces (dumbbell and optical flat). The results indicate that the proposed approach enjoys better performance than the conventional BWBSP-based method in terms of spatial resolution, accuracy, and efficient reconstructed points. An experiment of applying CBSP to measuring a moving A4 paper is also presented, demonstrating the success of our computational framework. Finally discussions concerning the limitations of this method are implemented.

Experimental study of temporal-spatial binary pattern projection for 3D shape acquisition.

Three-dimensional (3D) acquisition of an object with modest accuracy and speed is of particular concern in practice. The performance of digital sinusoidal fringe pattern projection using an off-the-shelf digital video projector is generally discounted by the nonlinearity and low switch rate. In this paper, a binary encoding method to encode one computer-generated standard sinusoidal fringe pattern is presented for circumventing such deficiencies. In previous work [Opt. Eng.54, 054108 (2015)OPEGAR0091-328610.1117/1.OE.54.5.054108], we have developed a 3D system based on this encoding tactic and showed its prospective application. Here, we first build a physical model to explain the mechanism of how to generate good sinusoidality. The phase accuracy with respect to the conventional spatial binary encoding method and sinusoidal fringe pattern is also comparatively evaluated through simulation and experiments. We also adopt two phase-height mapping relationships to experimentally compare the measurement accuracy among them. The results indicate that the proposed binary encoding strategy has a comparable performance to that of sinusoidal fringe pattern projection and enjoys advantages over the spatial binary method under the same conditions.

Modulation measuring profilometry with auto-synchronous phase shifting and vertical scanning.

To determine the shape of a complex object with vertical measurement mode and higher accuracy, a novel modulation measuring profilometry realizing auto-synchronous phase shifting and vertical scanning is proposed. Coaxial optical system for projection and observation instead of triangulation system is adopted to avoid shadow and occlusion. In the projecting system, sinusoidal grating is perpendicular to optical axis. For moving the grating along a direction at a certain angle to optical axis, 1D precision translation platform is applied to achieve purposes of both phase-shifting and vertical scanning. A series of fringe patterns with different modulation variations are captured by a CCD camera while scanning. The profile of the tested object can be reconstructed by the relationship between the height values and the modulation distributions. Unlike the previous method based on Fourier transform for 2D fringe pattern, the modulation maps are calculated from the intensity curve formed by the points with definite pixel coordinates in the captured fringe patterns. The paper gives the principle of the proposed method, the set-up of measurement system and the method for system calibration. Computer simulation and experiment results proved its feasibility.

3D shape measurement of the aspheric mirror by advanced phase measuring deflectometry.

An advanced Phase Measuring Deflectometry(PMD) is proposed to measure the three dimensional (3D) shape of the aspheric mirror. In the measurement process, a liquid crystal display(LCD)screen displaying sinusoidal fringe patterns and a camera observing the fringe patterns reflected via the tested mirror, are moved along the tested mirror optical axis, respectively. At each movement position, the camera records the fringe patterns of the screen located at two different positions. Using these fringe patterns, every camera pixels can find a corresponding point on the tested mirror and gets its coordinate and slope. By integrating, the 3D shape of the tested mirror can be reconstructed. Compared with the traditional PMD, this method doesn???t need complex calibration and can measure the absolute height of the aspheric mirror which has large range of surface geometries unambiguously. Furthermore, this method also has strong anti-noise ability. Computer simulations and preliminary experiment validate the feasibility of this method.