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An improved line-of-sight method for visibility analysis in 3D complex landscapes

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Science china(Information Sciences) 2010年第11期53卷 2185-2194页

作者： LIU Liu1, ZHANG LiQiang1, MA JingTao2. ZHANG Liang3, ZHANG XingMing1, XIAO ZhiQiang1 & YANG Ling1 1State Key Laboratory of Remote Sensing Science, Jointly Sponsored by Beijing Normal university and the Institute of Remote Sensing Applications of Chinese Academy of Sciences, Beijing 100875, china 2.TV America, Inc. 1145 Broadway Plaza Ste 605, Tacoma, WA 98407, USA 3{2. of geomatics and Urban Information, Beijing university of Civil Engineering and Architecture, Beijing 100044, china State Key Laboratory of Remote Sensing Science Jointly Sponsored by Beijing Normal University and the Institute of Remote Sensing Applications of Chinese Academy of Sciences Beijing China PTV America Inc. Tacoma USA school of geomatics and Urban Information Beijing University of Civil Engineering and Architecture Beijing China

This paper presents an efficient method for implementing visibility analysis on complex landscapes based on an improved LOS (line of sight) algorithm. The method determines the viewshed by analyzing the geometric relationship between the target points and viewpoint. It differentiates the visibility of the target points by the elevation information. Eventually the visual results related to the given viewpoint are rendered on three-dimensional landscapes. The visibility of some target points is computed by comparing their elevations with the viewpoint's height, thus is able to enhance the efficiency of the visibility analysis. This method can not only be applied in the visibility analysis of forest scenes, but also used in the analysis of the urban environment. Experiments show that the proposed method results in high efficiency and precision.

关键词： line of sight visibility analysis complex landscapes visual permeability

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户外AR空间信息表达及其虚实配准方法研究

武汉理工大学学报 2010年第12期32卷 98-101页

作者：武雪玲任福杜清运中国地质大学(武汉)地球物理与空间信息学院武汉430074 武汉大学资源与环境科学学院武汉430079

针对传统空间信息表达形式(例如地图等)不能满足使用者对视觉逼真度和人机交互自然性等需求的问题,将户外增强现实(Augmented Reality,AR)引入空间信息领域,致力于探索将地理数据库中的数字化空间信息精准叠加到真实地理场景之上的方法... 详细信息

针对传统空间信息表达形式(例如地图等)不能满足使用者对视觉逼真度和人机交互自然性等需求的问题,将户外增强现实(Augmented Reality,AR)引入空间信息领域,致力于探索将地理数据库中的数字化空间信息精准叠加到真实地理场景之上的方法,实现对真实地理环境的补充而非替代(区别于VR),进而增强用户对真实地理环境的感知能力和拓展其与现实世界的交互能力。通过分析户外AR与空间信息表达结合的研究现状、理论基础和重要性,提出户外AR空间信息表达的基本特征、系统结构。其中,虚实配准是难点,采用2.思路解决该问题,通过实例验证了方法的可行性。

关键词：户外AR 空间信息表达虚实配准

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Ce Anomalies of the Yangtze Region,South china,through the Ordovician and Silurian Transition

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Journal of Earth Science 2009年第6期20卷 941-948页

作者：严德天张丽琴李双建 Key Laboratory of Tectonics and Petroleum Resources of Ministry of Education China University of GeosciencesWuhan Institute of Geology and Geophysics Chinese Academy of Sciences school of geodesy and {2. Wuhan University Key Laboratory of Geospace Environment & geodesy of Ministry of Education Wuhan University Petroleum Exploration and Production Institute of SINOPEC

Systematic Ce anomalies for whole-rock have been obtained from the shale-dominated, continuous, and pelagic sedimentary sequences spanning the Ordovician/Silurian （O/S） boundary at the Tieshui （铁水） of Xiushan （秀山）, Chongqing （重庆）, South china. Ce anomalies across the O/S boundary are recognized in three intervals, Wufeng （五峰）, Guanyinqiao （观音桥） and Longmaxi （龙马溪）. The calculated Ce/Ce＊ values of Wufeng Formation range from 0.84 to 0.96 （avg. 0.90）. In the Guanyinqiao Formation, the values of calculated Ce/Ce＊ range from 0.73 to 0.85 （avg. 0.79）. The Ce/Ce＊ values of uppermost Longmaxi Formation range from 0.87 to 0.96 （avg. 0.91）. All along the section, the magnitude of the Ce anomaly is always negative, but is more significant in the Guanyinqiao Formation. The relatively higher Ce/Ce＊ values in the Wufeng and Longmaxi shales are likely to be due to the sediments deposited under rather reducing conditions. The Ce anomaly apparently does play some regular roles in the anoxic events that accompany prominent mass extinctions, and this work provides new data of critical importance for constraining models on the end-Ordovician anoxic events and mass extinctions.

关键词： Ce anomaly redox mass extinction Ordovician/Silurian boundary Yangtze platform.

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A study of real-time tide measurement

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A study of real-time tide measurement

The 2.d International Conference on Environmental and Engineering Geophysics

作者： Gang Chen Xinwen Cheng Jianhu Zhao school of Engineering china {2. of Geosciences Wuhan 430074 china school of geomatics and geodesy Wuhan {2. Wuhan 430079 china

＜正＞Tidal level plays a very important role in hydrographic survey for providing a vertical reference surface. Conventional tide measurement only generates a separate tide at each tide gauge, and can not meet completely with the requirement of continuous, precise and dynamitic hydrographic survey. It is necessary to look for a new method to acquire real-time tidal level when surveying vessel is cruising. The high continuity and credibility of GPS carrier phase differential technique can provide a possibility to overcome these shortcomings of the conventional method. In the paper, the GPS tidal level is acquired finally by time offset （delay） correction, attitude correction, height transformation, draft correction and a data filter. Time offset correction ensures attitude parameters derived from multibeam sounding system synchronization with GPS vertical solution. Attitude correction can eliminate the effect of attitude and transfer the height of GPS antenna to reference point （RP）. In order to calculate the instantaneous height of water surface, a draft correction also should be added into the correction. Tidal level should be a stable water surface within short time period. Thus, a low-pass filter needs to be implemented for the elimination of noise and the extraction of the long-period tidal level. By above processing, Finally, GPS tide solution is achieved. The kinematical GPS tidal level measurement method is implemented in an experiment. RTK and PPK are adopted in the experiment. GPS tide solutions and the tidal level observed at tide gauges are compared and analysed in the paper. The statistic result of the difference between the two tidal level solutions shows that GPS tidal level solutions have less than ±3 centimetres of standard bias with respect to tidal readings, and also proves that the methods of GPS real-time tide measurement and corresponding data processing are feasible and credible.

关键词： RTK (Real Time Kinematic) PPK (Post Processing Kinematic) tidal level height transformation

Research on The Application of Web Inspection System Based on CORS in City Inspection

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Research on The Application of Web Inspection System Based o...

第三届中国卫星导航学术年会

作者： Xu Ding,Jiming Guo,Mingduan Zhou,Heng Zhang school of geodesy and {2.,Wuhan university,12. Luoyu Road,Wuhan,china,430079

The traditional GPS RTD applied in city inspection has some shortages that inspection information can’t be returned to the control center real-time,data can’t be shared and inspection track can’t be monitored,so this paper designs the Web inspection system based on inverse RTD which adds one Mid-Server between CORS system and PDA,Mid-Server receives differential information and conducts differential correction,then the result returns to PDA which has no differential function,but should increase bidirectional communication module to receive the result returned from Mid-Server and upload the attribute information of inspection points to Mid-Server,indoor workers can get inspection information through Web platform *** results indicate that this technology has the advantages that information can exchange real-time,user can use cheaper PDA without differential function and can develop appropriate coping strategies timely,so it’s application in city inspection can avoid the shortages of traditional technology.

关键词： CORS Inverse RTD Web inspection system Mid-Server

Improving Global VTEC inversion with Inequality Constraint Least Square

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Improving Global VTEC inversion with Inequality Constraint L...

第三届中国卫星导航学术年会

作者： Hongping Zhang 1,2.Peiliang Xu 4,Maorong Ge 5,Wenhui Han 3 Changjiang Geng 2.1.State Key Laboratory of Information Engineering in Surveying,Mapping and Remote Sensing,Wuhan university,Wuhan 430070,china 2.GNSS Research Center,Wuhan university,Wuhan 430079,china 3 school of geodesy and geomatics,Wuhan university,Wuhan 430079,china 4.Disaster Prevention Research Institute,Kyoto university,Uji,Kyoto 611‐0011,Japan 5.Helmholtz Centre Potsdam,German Research Centre for Geosciences (GFZ),Telegrafenberg,14473 Potsdam,Germany

Currently,ground‐based GNSS stations of the International GNSS Service （IGS） are distributed unevenly around the *** of them locate on the mainland,while only a small part of them are scattered on some islands in the *** a consequence,grid vertical total electron content （VTEC） of ESA and CODE’s IONEX products appear many unreasonable zero values （in fact negative values）,especially for the years of 2.08 and 2.09 when the solar activity was rather *** improve this situation,this paper proposes an inequality‐constrained least squares method for the solution of Global Ionospheric Mapping （GIM） with spherical harmonic functions by imposing non‐negative inequality constraints in the areas where negative VTEC values may *** then apply the new method to 2.08 IGS *** results have shown that the new algorithm efficiently eliminates the unwanted behavior of negative VTEC values that can often be seen on both middle and high latitude area of south hemisphere （S90～S45） and north hemisphere （N5°～N9°） under current IGS *** repeatability of most GPS receivers’ DCBs have been improved ***,GIM products from this paper,CODE,JPL and ESA are compared with IGS final *** is found that inequality constraint improve the consistency of our GIM with them both at RMS and mean VTEC.

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基于Hilbert-Huang变换的结构损伤诊断

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武汉理工大学学报 2004年第8期26卷 44-47页

作者：李书进虞晖瞿伟廉武汉理工大学土木工程与建筑学院武汉430070 武汉大学测绘学院武汉430079

对 Hilbert- Huang变换 (HHT)在结构损伤诊断中的应用进行了分析。 Hilbert- Huang变换是一种适用于非线性、非平稳信号 ,且具有自适应性的新的数据处理方法 ,将该方法应用于结构的反应分析 ,能有效地提取结构的损伤特征 ,从而对结构的... 详细信息

对 Hilbert- Huang变换 (HHT)在结构损伤诊断中的应用进行了分析。 Hilbert- Huang变换是一种适用于非线性、非平稳信号 ,且具有自适应性的新的数据处理方法 ,将该方法应用于结构的反应分析 ,能有效地提取结构的损伤特征 ,从而对结构的健康状况进行诊断。

关键词：损伤诊断 Hilbert-Huang变换 EMD方法结构健康诊断

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Artificial Immune System and its Applications in GPS Single Frequency Precise Point Positioning

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Artificial Immune System and its Applications in GPS Single ...

2.08 3rd International Conference on Intelligent System and Knowledge Engineering(ISKE 2.08)

作者： Chengquan Xu Suxia Xu Wei Chen Department of Geography Minjiang university china Dept. of Cognitive Science Xiamen university Xiamen 361005 china school of geodesy & geomatics Wuhan university 430079 china

The natural immune system is a robust and powerful information process system that demonstrates features such as distributed control, parallel processing and adaptation. Artificial Immune Systems （AIS） are machine-learning algorithms that embody some of the principles and attempt to take advantages of the benefits of natural immune systems for use in tackling complex problem domains. Using the artificial immune algorithm in GPS data Processing can solve the GPS nonlinear models directly and avoid the ill- conditions. The principle and algorithm steps of the AIS are introduced and it’s application in GPS single frequency precise point positioning （PPP） is discussed detailed. Numerical result shows that the single frequency PPP model solved by AIS can reach an accuracy of sub-meter level.

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Fuzzy C-means Clustering-based Multilayer Perceptron Neural Network for Liver CT Images Automatic Segmentation

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Fuzzy C-means Clustering-based Multilayer Perceptron Neural ...

2.10 Chinese Control and Decision Conference

作者： Yuqian Zhao~(1,2.,Yunlong Zan~1,Xiaofang Wang~1,Guiyuan Li~2.1.school of Info-Physics & geomatics Engineering,Central South {2.,Changsha 410083,china 2.Cancer Research Institute,Central South {2.,Changsha 410078,china

＜正＞A new liver segmentation algorithm is ***,the threshold method was used to remove the ribs and spines in the initial image,and the fuzzy C-means clustering algorithm and morphological reconstruction filtering were used to segment the initial liver CT *** the multilayer perceptron neural network was trained by the segmentation result of initial image with the back-propagation *** adjacent slice CT image was segmented with the trained multilayer perceptron neural ***,morphological reconstruction filtering was used to smooth the contour of the liver *** experimental results show that the proposed algorithm can effectively segment the livers from CT images,despite the gray level similarity of adjacent organs and different gray level of tumors in the liver.

关键词： Liver Segmentation Fuzzy C-means Algorithm Multilayer Perceptron Neural Network Morphological Reconstruction Filtering