Visibility is an important atmospheric parameter that is gaining increasing global attention. This study introduces a back-propagation neural network method based on genetic algorithm optimization to obtain visibility...Visibility is an important atmospheric parameter that is gaining increasing global attention. This study introduces a back-propagation neural network method based on genetic algorithm optimization to obtain visibility directly using light detection and ranging(lidar) signals instead of acquiring extinction coefficient. We have validated the performance of the novel method by comparing it with the traditional inversion method, the back-propagation(BP) neural network method,and the Belfort, which is used as a standard value. The mean square error(MSE) and mean absolute percentage error(MAPE) values of the genetic algorithm-optimized back propagation(GABP) method are located in the range of 0.002 km2–0.005 km^2 and 1%–3%, respectively. However, the MSE and MAPE values of the traditional inversion method and the BP method are significantly higher than those of the GABP method. Our results indicate that the proposed algorithm achieves better performance and can be used as a valuable new approach for visibility estimation.展开更多
道路交叉口是道路网络组成的重要部分,对道路交叉口的定位与信息提取是掌握道路属性、获取道路网络拓扑结构的重要基础。传统的基于影像的道路交叉口方法对此讨论较少,且存在检测率较低、自动化程度不高等问题,而人工操作成本较高、费...道路交叉口是道路网络组成的重要部分,对道路交叉口的定位与信息提取是掌握道路属性、获取道路网络拓扑结构的重要基础。传统的基于影像的道路交叉口方法对此讨论较少,且存在检测率较低、自动化程度不高等问题,而人工操作成本较高、费时费力。针对从遥感数据中识别与获取道路交叉口信息的问题,提出一种从机载LiDAR点云数据中提取道路交叉口轮廓的方法,该方法的自动化程度较高。首先,利用角度纹理信息(angular texture signature,ATS)对道路交叉口进行粗定位,通过基于点密度在噪声的空间数据库中对所提取的结果进行聚类分析(density-based spatial clustering of application with noise,DBSCAN)和剔除孤立点确定道路交叉口提取区域;然后,引入环形剖面方法进行边缘提取,借助高程信息进行辅助判断,拟合出道路平行边缘;最后,利用Ziplock Snake算法提取出道路交叉口轮廓。实验采用完全自主的研发平台,经历了较多次实验和改进,其结果表明,该方法对道路交叉口的检测率较高,对轮廓提取的精度较高,不仅可行,而且有效。展开更多
The advantage of lidar over other wind sensors is presented in this paper. With more than 20 years research, the development of the space-borne wind lidar is reviewed. Longer-term investigation has made many technolog...The advantage of lidar over other wind sensors is presented in this paper. With more than 20 years research, the development of the space-borne wind lidar is reviewed. Longer-term investigation has made many technologies suitable for the wind lidar measurement from an orbital platform become mature. However, there are still some problems to be solved. In order to obtain the optimal performance in wind detection, great importance is being attached to the simulation of a virtual space-borne wind lidar system on computer as developed by NASA and ESA.展开更多
In this paper, the effect of scintillation on system SNR is discussed. Atmospheric scintillation is described and log amplitude variance in slant path is given. In addition, the simulations of system SNR at different ...In this paper, the effect of scintillation on system SNR is discussed. Atmospheric scintillation is described and log amplitude variance in slant path is given. In addition, the simulations of system SNR at different propagation path and different height are obtained. The results from simulation show that atmospheric scintillation has an important effect on SNR of DIAL system, especially near the ground.展开更多
This paper, based on the Kavaya-Suni format, discusses the signal-to-noise ratio equation of the diffraction-limited coherent CO 2 lidar in detail, which is applied to atmospheric turbulence. The cumulative SNR and r...This paper, based on the Kavaya-Suni format, discusses the signal-to-noise ratio equation of the diffraction-limited coherent CO 2 lidar in detail, which is applied to atmospheric turbulence. The cumulative SNR and relative SNR, which are all affected by the nonlinear effects of the diffraction-limited Gaussian beam, atmospheric molecule and atmospheric turbulence, are simulated by microcomputer. Six instructions for the optimal design of IR CO 2 Coherent Lidar System, are provided.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.41405014)
文摘Visibility is an important atmospheric parameter that is gaining increasing global attention. This study introduces a back-propagation neural network method based on genetic algorithm optimization to obtain visibility directly using light detection and ranging(lidar) signals instead of acquiring extinction coefficient. We have validated the performance of the novel method by comparing it with the traditional inversion method, the back-propagation(BP) neural network method,and the Belfort, which is used as a standard value. The mean square error(MSE) and mean absolute percentage error(MAPE) values of the genetic algorithm-optimized back propagation(GABP) method are located in the range of 0.002 km2–0.005 km^2 and 1%–3%, respectively. However, the MSE and MAPE values of the traditional inversion method and the BP method are significantly higher than those of the GABP method. Our results indicate that the proposed algorithm achieves better performance and can be used as a valuable new approach for visibility estimation.
文摘道路交叉口是道路网络组成的重要部分,对道路交叉口的定位与信息提取是掌握道路属性、获取道路网络拓扑结构的重要基础。传统的基于影像的道路交叉口方法对此讨论较少,且存在检测率较低、自动化程度不高等问题,而人工操作成本较高、费时费力。针对从遥感数据中识别与获取道路交叉口信息的问题,提出一种从机载LiDAR点云数据中提取道路交叉口轮廓的方法,该方法的自动化程度较高。首先,利用角度纹理信息(angular texture signature,ATS)对道路交叉口进行粗定位,通过基于点密度在噪声的空间数据库中对所提取的结果进行聚类分析(density-based spatial clustering of application with noise,DBSCAN)和剔除孤立点确定道路交叉口提取区域;然后,引入环形剖面方法进行边缘提取,借助高程信息进行辅助判断,拟合出道路平行边缘;最后,利用Ziplock Snake算法提取出道路交叉口轮廓。实验采用完全自主的研发平台,经历了较多次实验和改进,其结果表明,该方法对道路交叉口的检测率较高,对轮廓提取的精度较高,不仅可行,而且有效。
基金supported by National High Tech 863 Project(No.2002AA135280)National Natural Science Foundation of China No.40176011International Bureau of BMBF
文摘The advantage of lidar over other wind sensors is presented in this paper. With more than 20 years research, the development of the space-borne wind lidar is reviewed. Longer-term investigation has made many technologies suitable for the wind lidar measurement from an orbital platform become mature. However, there are still some problems to be solved. In order to obtain the optimal performance in wind detection, great importance is being attached to the simulation of a virtual space-borne wind lidar system on computer as developed by NASA and ESA.
文摘In this paper, the effect of scintillation on system SNR is discussed. Atmospheric scintillation is described and log amplitude variance in slant path is given. In addition, the simulations of system SNR at different propagation path and different height are obtained. The results from simulation show that atmospheric scintillation has an important effect on SNR of DIAL system, especially near the ground.
文摘This paper, based on the Kavaya-Suni format, discusses the signal-to-noise ratio equation of the diffraction-limited coherent CO 2 lidar in detail, which is applied to atmospheric turbulence. The cumulative SNR and relative SNR, which are all affected by the nonlinear effects of the diffraction-limited Gaussian beam, atmospheric molecule and atmospheric turbulence, are simulated by microcomputer. Six instructions for the optimal design of IR CO 2 Coherent Lidar System, are provided.
