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Development on filtering algorithms of Airborne LiDAR Point Clouds

International Conference on Vibration, Structural Engineering and Measurement (ICVSEM2012)

作者： Shi, Jianqing Jiang, Tingchen Jiao, Minglian Huaihai Inst Technol Sch Geodesy & Geomat Engn Lianyungang 222005 Peoples R China

ISBN: (纸本)9783037855072

Airborne LiDAR is a new kind of surveying technology of remote sensing eveloped rapidly during recent years. Raw laser scanning point clouds data include terrain points, building points, vegetation points, outlier points, etc.. In order to generate digital elevation model (DEM) and three-dimensional city model,these point clouds data must be filtered. Mathematical morphology based filtering algorithm, slope based filtering algorithm, TIN based filtering algorithm, moving surface based filtering algorithm, scanning lines based filtering algorithm and so on several representative filtering algorithms for LiDAR point clouds data have been introduced and discussed and contrasted in this paper. Based on these algorithms summarize the studying progresss about the filtering algorithm of airborne LiDAR point clouds data in home and abroad. In the end, the paper gives an expectation which will provides a reference for the following relative study.

关键词： Airborne LiDAR Laser scanning Point clouds filtering algorithm Expectation

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Adaptive enhancement method of irregular low-pixel architectural design image based on lightness component

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IMAGING SCIENCE JOURNAL 2025年第1期73卷 70-83页

作者： Qu, Mei Nanyang Inst Technol Sch Architecture Nanyang 473000 Henan Peoples R China

This study explores adaptive enhancement for irregular, low-pixel architectural design images, focusing on lightness components. Utilizing a median filter and wavelet threshold method removes image noise, followed by grayscale conversion in HSV space. Applying Retinex theory generates the initial enhanced image, further improved through wavelet transform image fusion technology, resulting in the final enhanced architectural design image. Experimental results demonstrate the method's effectiveness in adapting and enhancing irregular, low-pixel architectural design images, achieving notably improved outcomes. The proposed approach successfully extracts and utilizes valuable image information, enhancing overall image quality. This study found that the proposed method can effectively extract and better utilize useful information in images, achieving more ideal image enhancement effects.

关键词： Lightness component low-pixel image irregular image architectural design image adaptive enhancement image fusion filtering algorithm module structure

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Efficient filtering based on Kullback-Leibler divergence for wireless networked control systems with Markovian packet losses

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INTERNATIONAL JOURNAL OF CONTROL 2023年第10期96卷 2587-2599页

作者： Dong, Jianhuai Dong, Zhixuan Fujian Jiangxia Univ Sch Elect Informat Sci Fuzhou Peoples R China Fudan Univ Sch Microelect Shanghai Peoples R China

In this paper, the filtering issues are investigated for wireless networked control systems (WNCSs) with Markovian packet losses. In WNCSs, Markovian packet losses often occur in both control and feedback channels, and User Datagram Protocol (UDP) is usually used to ensure real-time control and energy saving. First, the optimal filtering algorithm for WNCSs with Markovian packet losses is obtained. However, it cannot be applied in practice as its running time increases exponentially with time. Then a computationally efficient filtering algorithm is developed by approximating the probability density function of the estimated value to a Gaussian distribution, where the approximation is obtained by minimising the Kullback-Leibler divergence (KLD). Finally, the upper and lower bounds of the performance of the KLD-based approximate filter and sufficient conditions of its stability are obtained. Numerical examples are given to verify the effectiveness of the theoretical results.

关键词： Wireless networked control systems Markovian packet losses filtering algorithm Kullback-Leibler divergence stability

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New filtering for ATMOSTNVALUE and its weighted variant: A Lagrangian approach

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CONSTRAINTS 2015年第3期20卷 362-380页

作者： Cambazard, Hadrien Fages, Jean-Guillaume Univ Grenoble Alpes G SCOP F-38000 Grenoble France CNRS G SCOP F-38000 Grenoble France COSLING SAS F-44307 Nantes 3 France

The AtMostNValue global constraint, which restricts the maximum number of distinct values taken by a set of variables, is a well known NP-Hard global constraint. The weighted version of the constraint, AtMostWValue, where each value is associated with a weight or cost, is a useful and natural extension. Both constraints occur in many industrial applications where the number and the cost of some resources have to be minimized. This paper introduces a new filtering algorithm based on a Lagrangian relaxation for both constraints. This contribution is illustrated on problems related to facility location, which is a fundamental class of problems in operations research and management sciences. Preliminary evaluations show that the filtering power of the Lagrangian relaxation can provide significant improvements over the state-of-the-art algorithm for these constraints. We believe it can help to bridge the gap between constraint programming and linear programming approaches for a large class of problems related to facility location.

关键词： Global constraint filtering algorithm Lagrangian relaxation At most n values

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Event-based efficient filtering for wireless network control systems with User Datagram Protocol

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INTERNATIONAL JOURNAL OF CONTROL 2021年第11期94卷 2980-2991页

作者： Dong, Jianhuai Dong, Zhixuan Guo, Wenlong Fujian Jiangxia Univ Coll Elect & Informat Sci Fuzhou Fujian Peoples R China Fudan Univ Sch Microelect Shanghai Peoples R China

In this paper, the filtering issues are investigated for event-based Wireless Network Control Systems (WNCSs) with User Datagram Protocol (UDP). Because the optimal estimation of WCNSs with packet loss in both control and observation channels via UDP cannot be applied in practice due to the exponential increase of the computation, and in order to reduce the energy consumption of wireless communication nodes, an efficient recursive filter is developed for the event-based WNCSs with UDP. The state estimation and the filtering error covariance are derived from the interacting multiple model (IMM) methods, and the filter gain is determined by minimising an upper bound of the filtering error covariance. It is proved that the stability of the minimum upper bound of the filtering error covariance is only related to the actual arrival rate of the observation packet, and the minimum upper bound converges to the error covariance of the optimal estimation of the corresponding system with Transmission Control Protocol (TCP) if both the trigger threshold and the control input tend to zero. Numerical examples are given to verify the effectiveness and feasibility of the theoretical results.

关键词： Wireless network control systems packet losses filtering algorithm event-triggered mechanism stability performance

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KALMOD, A STOCHASTIC-DETERMINISTIC MODEL FOR SIMULATING GROUNDWATER-FLOW WITH KALMAN filtering

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HYDROLOGICAL SCIENCES JOURNAL-JOURNAL DES SCIENCES HYDROLOGIQUES 1992年第4期37卷 375-389页

作者： ZHOU, YX VANGEER, FC International Institute for Environmental and Hydraulic Engineering TNO Institute of Applied Geoscience

This paper presents the program KALMOD which has been developed to enable the execution of the integration of the Kalman filtering and the numerical groundwater flow model MODFLOW on microcomputers. The program can be applied to quantify and reduce the uncertainty of the groundwater flow model, and to analyse and design groundwater monitoring networks. KALMOD consists of a preprocessor, a processor and a postprocessor. The preprocessor acts as an interface between the user and the processor. The processor manipulates the measurement processes and carries out the filtering tasks. The filtering algorithm is implemented so that it is relatively efficient with respect to computer memory and execution time. The postprocessor was designed to present the model results in graphics. The program is suitable for small scale problems and for educational purposes.

关键词： .consists groundwater monitoring Numerical groundwater Flow Model Applied Geoscience Kalman filtering Preprocessor simulating groundwater flow KALMOD stochastic-deterministic postprocessor filtering algorithm computer memory

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Optimal filtering and control for wireless networked closed-loop control systems

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INTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING 2020年第10期34卷 1466-1482页

作者： Dong, Jianhuai Dong, Zhixuan Fujian Jiangxia Univ Coll Elect & Informat Sci Fuzhou 350108 Peoples R China Fudan Univ Sch Microelect Shanghai Peoples R China

This article studies the optimal filtering and control for wireless networked control systems (WNCSs). In WNCSs, packets may be lost in both control and feedback channels and user datagram protocol is usually used to improve the performance of the real-time control. Relevant literature indicates that the conventional optimal filtering for such a system cannot be applied in practice due to the complex calculation with Gaussian mixtures. This paper proposes a novel scheme to realize the optimal filtering and the linear quadratic Gaussian control for WNCSs, in which the controlled node performs a local estimation and the remote-control node performs the final estimation and control, and a synchronization of two estimators is guaranteed by a communication mechanism. An optimal filtering algorithm is developed, the stability condition of the filtering error covariance is obtained, optimal finite-horizon and infinite-horizon control are derived, and the stability of the closed-loop control system is proved. Numerical simulations show the validity and feasibility of the theoretical results.

关键词： communication mechanism filtering algorithm LQG control packet loss stability wireless networked control systems

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Using object-based analysis to derive surface complexity information for improved filtering of airborne laser scanning data

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Frontiers of Earth Science 2017年第1期11卷 11-19页

作者： Menglong YAN Thomas BLASCHKE Hongzhao TANG Chenchao XIAO Xian SUN Daobing ZHANG Kun FU Key Laboratory of Technology in Geo-Spatial Information Processing and Application System Institute of Electronics Chinese Academy of Sciences Beijing 100190 China Z GIS - Centre for Geoinformatics and Department for Geography and Geology University of Salzburg Salzburg A-5020 Austria Satellite Mapping Application Center State Bureau of Surveying and Mapping Beijing 100048 China China Aero Geophysical Survey and Remote Sensing Center for Land and Resources Beijing 100083 China

Airborne laser scanning （ALS） is a technique used to obtain Digital Surface Models （DSM） and Digital Terrain Models （DTM） efficiently, and filtering is the key procedure used to derive DTM from point clouds. Generating seed points is an initial step for most filtering algorithms, whereas existing algorithms usually define a regular window size to generate seed points. This may lead to an inadequate density of seed points, and further introduce error type I, especially in steep terrain and forested areas. In this study, we propose the use of object- based analysis to derive surface complexity information from ALS datasets, which can then be used to improve seed point generation. We assume that an area is complex if it is composed of many small objects, with no buildings within the area. Using these assumptions, we propose and implement a new segmentation algorithm based on a grid index, which we call the Edge and Slope Restricted Region Growing （ESRGG） algorithm. Surface complexity information is obtained by statistical analysis of the number of objects derived by segmentation in each area. Then, for complex areas, a smaller window size is defined to generate seed points. Experimental results show that the proposed algorithm could greatly improve the filtering results in complex areas, especially in steep terrain and forested areas.

关键词： airborne laser scanning object-based analysis surface complexity information filtering algorithm

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Research on a System Noise Simulation and filtering Method in Tunable Diode Laser Absorption Spectroscopy Technology

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JOURNAL OF APPLIED SPECTROSCOPY 2023年第4期90卷 867-875页

作者： Yan, Wang Fang, Wang Rui, Zhang Bo, Yan Yang, Si-Yan Li, Xin-Bo Tianjin Chengjian Univ Sch Comp & Informat Engn Tianjin Peoples R China Tianjin Univ Sci & Technol Coll Elect Informat & Automat Tianjin Peoples R China Hebei Univ Architecture Coll Elect Engn Zhangjiakou Peoples R China

To solve the problem of multiple noise interference when tunable diode laser absorption spectroscopy (TDLAS) technology is used for gas concentration detection, the principles of Kalman, moving average, wavelet transform, and singular value decomposition four filtering algorithm principles and system noise sources are analyzed. MATLAB simulation software is used to simulate the relationship curve of thermal noise, shot noise, relative intensity noise of lasers, and the characteristic value of harmonic signals. Four filtering algorithms are used to process the noise, and the best filtering algorithm is selected. Moreover, a TDLAS experimental system with ethylene gas as the detection object is designed in this paper. The experimental results show that the singular value decomposition method among the four filtering algorithms has the best effect in removing thermal noise, shot noise, and laser noise. After filtering is performed, the accuracy of the continuous detection of the system is improved, and the purpose of reducing or even eliminating system noise can be achieved. After processing occurs, the signal-to-noise ratio of the detected signal of the system is improved by 57 dB, and the noise removal rate of the system reaches 66.7%.

关键词： tunable diode laser absorption spectrum filtering algorithm noise simulation ethylene

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filtering for the Interference Signal Caused by Grounding Potential Difference in High-Voltage Disconnector

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IEEE SENSORS JOURNAL 2021年第6期21卷 7768-7775页

作者： Bian Haihong Cao Minjian Zhao Kai Wang Lihui Nanjing Inst Technol Sch Elect Power Engn Nanjing 211167 Peoples R China Nanjing Inst Technol Jiangsu Collaborat Innovat Ctr Smart Distribut Ne Nanjing 211167 Peoples R China Southeast Univ Sch Elect Engn Nanjing 210096 Peoples R China Southeast Univ Sch Instrument Sci & Engn Nanjing 210096 Peoples R China

The disconnector operation in the high-voltage substations forms a very fast transient overvoltage (VFTO), which leads to a sudden rise in local grounding potential. Due to double grounding of the secondary cable, the current transformer signal is interfered by the grounding grid potential difference. To study the mechanism of the interference signal, a simulation model based on the electro-magnetic transient program is built and the coupling path of the grounding grid potential difference is analyzed. According to the characteristics of interference signal, an adaptive algorithm is put forward and it mainly consists of three parts, including starting element, decision algorithm, and filtering algorithm. By selecting the appropriate parameters of wavelet transform, the filtering algorithm can discompose and reconstruct signal to remove the interference signal. The simulation results demonstrate that the filtering algorithm can effectively eliminate the interference signal caused by the grounding grid potential difference, with a 91 reduction of the root mean square error and a 135 improvement of the signal-to-noise ratio. Moreover, the accuracy of the measured data is ensured and the reliability of the relay protection is improved.

关键词： Grounding Interference Transient analysis filtering algorithms Wires Substations Electric potential Disconnector operation VFTO grounding grid potential difference simulation model filtering algorithm

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