机载LiDAR技术

机载LiDAR集成了GPS、IMU、激光扫描仪新一代航空遥感系统,能利用飞行获取的原始数据直接生成DEM和正射影像图,而无需任何或仅需少量的地面控制点。与传统的摄影测量技术相比,机载LiDAR可以节省大量的人力、时间和经费。在过去十年,机载LiDAR作为精确、快速的地球表面三维测量方法已得到广泛的认同,本文详细介绍了机载LiDAR的基本原理、技术结构及数据处理流程。     

国家1:50000数据库更新工程总体设计研究与技术创新

为了全面提高1:50000数据库的信息现势性和要素完整性,我国"十一五"期间组织实施了国家1:50000数据库更新工程.介绍该工程总体技术研究与技术创新工作,包括研究设计以地形数据全要素更新、全区域变化检测和全过程质量控制为主要特征的1:50000数据库全面更新模式,研究提出符合我国大面积快速更新实际需要的缩编更新优先、影像一体化更新为主的主体更新方法,设计研制规模化更新所需的生产技术系统,制定配套的生产技术规定,建立规模化更新生产业务体系,并在全国大规模更新生产中广泛使用.

Abstract：

The currency of geographic data refers to its consistency with respect to the real world, and plays a criti-cal role in geographic information service and applications. In order to improve the quality of geographic informa-tion service, State Bureau of Surveying and Mapping of China had launched a five year's national campaign to up-date 1 : 50000 topographic database. This paper outlines the master design and technical development of this na-tional updating engineering, which adopts a full coverage updating strategy characterized by all element topo-graphic data modeling, change detection in all related areas, and whole process data quality controlling. High resolution image-based updating and large-scale data generalization-based updating were developed and used as two majors updating techniques, a series of technical production specifications were made, Based on the above, a technical system for large scale updating production, mainly including image based updating software and data generalization based updating software, has been developed and equipped to a large number of production units. The new technical pro-duction system has been successfully implemented in national campaign to update 1 : 50000 topographic database.     

地质灾害变形监测系统开发及应用

地质灾害监测环境非常复杂,特别是在恶劣天气下,传统周期性变形监测的方法不能够实时获取地质灾害所处的状态。根据传统变形监测工作流程及相应的质量技术要求,结合变形监测规范的要求和实际生产习惯,研制了基于测量机器人集机载控制网观测、变形监测自动数据采集、数据处理、精度统计、手薄报表输出、数据平差、分析预测预报于一体的变形监测数据处理系统DMPS,并应用湖北省黄冈市白莲河抽水蓄能电站的边坡监测。     

Contribution of new AAM data source to δLOD excitation

Data sets of the changes of the length of day (ΔLOD) measured by space geodetic techniques and of the atmospheric angular momentum (AAM) derived from global meteorological data by the National Meteorological Center (NMC) and the National Centers for Environmental Prediction/National Center for Atmospheric Research (NCEP/NCAR) are used to reanalyze and study the excitations of ΔLOD, and to examine and compare the contribution of each AAM series to ΔLOD. The main results are as follows. 1. The AAM reanalyzed with the assimilated global meteorological data by NCEP/NCAR are more accurate and have lower noise than the original AAM derived by NMC. The NCEP/NCAR-based AAM is more consistent with the changes of the length-of-day series. 2. The NCEP reanalysed AAM data may better explain the non-tidal LOD variations on intraseasonal to interannual time scales, especially on the quasi-biennial time scale. The atmosphere cannot, however, explain all LOD variations; other excitation sources are possible. 3. The effects of atmosphere on the estimated values of tides for ΔLOD components up to a month are weak. The preliminary results of the annual and semiannual tides can be estimated after removing the effects of atmosphere from ΔLOD. Received: 27 May 1998 / Accepted: 22 March 1999     

松毛虫危害的光谱特征与虫害早期探测模式

根据生态学特征，本文将松毛虫危害的针叶样品分为５个等级，对其反射光谱和叶绿素含量进行了测量分析。结果表明，随受害程度加重，叶绿素含量降低，５５０ｎｍ处的反射率、近红外肩反射率与红光最低反射率之差及红界一阶导数谱最大值均呈下降趋势，６３０ｎｍ处反射率呈上升趋势，红界光谱蓝移、叶绿素反射峰红移明显。应用逐步判别分析法对比分析证实了细分光谱特征参量比绿、红、近红外三波段反射率参量有更强的判别分类能力，这就为用细分光谱特征参量早期遥感探测松毛虫害提供了判别模式。     

星载雷达Radarsat数据产品选择及在地质探测中的应用

结合生产科研实践,在论述星载雷达成像方式及Radarsat 数据产品主要特点的基础上,针对以岩性识别和构造分析为主要研究内容的地质探测领域,着重讨论分析了波束模式、视角范围、卫星姿态、时相、数据处理级别等影响数据产品选择的主要因素,并提出地质探测领域Radarsat 数据产品的选择原则及参考意见,供广大遥感地质工作者在充分利用这一新型遥感数据源时参考。     

三层BP网隐层节点数确定方法的研究

对确定三层BP网络隐层节点数的理论依据和现有做法进行了研究,提出了一种三层BP网络隐层节点数的双向确定法     

数字化地图印刷一种随机挂网计算模型

基于彩色图像像素3刺激值与相应网点面积率之间的α幂修正的Neugebauer方程,建立由常规的调幅网为基础的调频挂网计算模型,以此实现分色胶片随机挂网     

Long-term behavior and statistical characterization of BeiDou signal-in-space errors

GPS Solutions - We derive orbit and clock errors for BeiDou satellites from March 1, 2013, to September 30, 2016 by comparing broadcast ephemerides with the precise ephemerides produced by Wuhan...     

An enhanced approach for surface flow routing over drainage‐constrained triangulated irregular networks

The accuracy and efficiency of the simulations in distributed hydrological models must depend on the proper estimation of flow directions and paths. Numerous studies have been carried out to delineate the drainage patterns based on gridded digital elevation models (DEMs). The triangulated irregular network (TIN) has been increasingly applied in hydrological applications due to the advantages of high storage efficiency and multi‐scale adaptive performance. Much of the previous literature focuses mainly on filling the depressions on gridded DEMs rather than treating the special cases in TIN structures, which has hampered its applications to hydrological models. This study proposes a triangulation‐based solution for the removal of flat areas and pits to enhance the simulation of flow routing on triangulated facet networks. Based on the drainage‐constrained TIN generated from only a gridded DEM by the compound point extraction (CPE) method, the inconsistent situations including flat triangles, V‐shape flat edges and sink nodes are respectively identified and rectified. The optimization algorithm is an iterative process of TIN reconstruction, in which the flat areas are generalized into their center points and the pits are rectified by embedding break lines. To verify the proposed algorithm and investigate the potential for flow routing, flow paths of steepest descent are derived by the vector‐based tracking algorithm based on the optimized TIN. A case study of TIN optimization and flow path tracking was performed on a real‐world DEM. The outcomes indicate that the proposed approach can effectively solve the problem of inconsistencies without a significant loss in accuracy of the terrain model.