Vehicle Detection and Attribution from a Multi-Sensor Dataset Using a Rule-Based Approach Combined with Data Fusion.

Vehicle detection using data fusion techniques from overhead platforms (RGB/MSI imagery and LiDAR point clouds) with vector and shape data can be a powerful tool in a variety of fields, including, but not limited to, national security, disaster relief efforts, and traffic monitoring. Knowing the location and number of vehicles in a given area can provide insight into the surrounding activities and patterns of life, as well as support decision-making processes. While researchers have developed many approaches to tackling this problem, few have exploited the multi-data approach with a classical technique. In this paper, a primarily LiDAR-based method supported by RGB/MSI imagery and road network shapefiles has been developed to detect stationary vehicles. The addition of imagery and road networks, when available, offers an improved classification of points from LiDAR data and helps to reduce false positives. Furthermore, detected vehicles can be assigned various 3D, relational, and spectral attributes, as well as height profiles. This method was evaluated on the Houston, TX dataset provided by the IEEE 2018 GRSS Data Fusion Contest, which includes 1476 ground truth vehicles from LiDAR data. On this dataset, the algorithm achieved a 92% precision and 92% recall. It was also evaluated on the Vaihingen, Germany dataset provided by ISPRS, as well as data simulated using an image generation model called DIRSIG. Some known limitations of the algorithm include false positives caused by low vegetation and the inability to detect vehicles (1) in extremely close proximity with high precision and (2) from low-density point clouds.

Simulations of vehicular optical wireless communication systems and comparisons with DSRC systems.

Optical wireless communication (OWC) has been proposed as a complementary technique to radio frequency (RF) communications for vehicular applications. OWC systems can be categorized into two types based on the transmitters: the first one is the light-emitting diode (LED)-based OWC system, and the second is the laser diode (LD)-based OWC system. Simulations of both types of OWC systems are presented in this paper. To simulate the OWC systems precisely, outdoor experiments of OWC systems have been done and the measurements of background noise are applied in the simulations. In terms of the LED-based OWC system, the impulse responses are obtained by an improved ray tracing algorithm. To reduce the computational complexity, visibility graphs are applied in the improved ray tracing algorithm. Compared with the brute force algorithm, our improved algorithm is able to reduce the computational complexity from O(n3) to O(n2log⁡(n)), where n is the number of mobile terminals. In LD-based OWC systems, the performance and stability are highly dependent on the tracking system in vehicular applications. Therefore, this paper also analyzes the requirements of tracking accuracy in LD-based OWC systems. Finally, the simulated LED-based OWC system is compared with the dedicated short-range communication (DSRC) system under different traffic densities. Our experimental and simulation results have demonstrated that OWC can be a complementary technique for DSRC under conditions of high traffic density.

Bistatic coherent laser radar signal-to-noise ratio.

We investigate the signal-to-noise ratio (SNR) for a bistatic coherent laser radar (CLR) system. With a bistatic configuration, the spatial resolution is determined by the overlap of the transmit beam and the virtual backpropagated local oscillator beam. This eliminates the trade-off between range resolution and the bandwidth of the transmitted pulse inherent in monostatic systems. The presented analysis is completely general in that the expressions can be applied to both monostatic and bistatic CLR systems. The heterodyne SNR is computed under the assumption of untruncated Gaussian optics and untruncated Gaussian beam profiles. The analysis also includes the effects of refractive turbulence. The results show that, for maximum SNR, small transmit and local oscillator beam profiles (e-1 intensity radius) are desired.

Development of an amplitude-modulated Nd:YAG pulsed laser with modulation frequency tunability up to 60 GHz by dual seed injection.

A pulsed, modulation frequency tunable, frequency-doubled Nd:YAG laser has been devised for use in target detection through turbid media. A modulated pulse laser radar system offers many advantages in target detection, such as significant signal contrast enhancement, compared with conventional remote-sensing systems. By implementation of the dual-longitudinal-mode seed injection technique, the modulation frequency of the designed Q-switched laser can be tuned from 250 MHz up to 60 GHz in steps of 250 MHz while maintaining a modulation depth of at least 75%. This provides the ability to explore propagation and scattering properties further at previously unattainable high RF modulation frequencies.