海图上点群状特征的识别与量测          下载免费PDF全文

李志炜  朱颖  陆毅  晏天翔  谢丛涛 《海洋测绘》2009,29(3):16-18

点群状（包括图斑群）目标在GIS数据中有大量的实例,由于它不同于单个独立的点状要素,在海图自动综合中如何对其分布特性进行识别并加以定量描述,是进行点群综合过程中的关键问题。主要介绍如何利用Delaunay三角网与Voronoi图两种模型对点群状目标分布特性进行描述,并通过对Delaunay三角网与Voronoi图的“蚕食”以及引入图像处理概念将密度问题转化为图像处理问题的方法,直接或间接对点群状目标进行识别与量测。  相似文献   

基于“两证合一”的城镇地籍调查技术路线探讨与研究     

陈诚  黄悦康 《四川测绘》2009,32(1):32-34

根据物权法的规定,为保证不动产房屋产权的合法唯一性,房产证和土地证必须合二为一,这样同时可以减少登记机关重复审批以及加强政府机关效能建设。本文针对“两证合一”的城镇地籍调查作技术路线探讨与研究。  相似文献   

GPS校正点选取对RTK平面测量精度的影响分析   总被引：1，自引：0，他引：1  

刘强  姚宜斌  王晶  张瑞  丁克良 《测绘信息与工程》2009,34(3):8-9

以一次试验为基础,对其中GPS静态控制网得到的坐标和RTK测得的GPS静态控制网的点的坐标进行比较和分析,分析了GPS点校正过程中,点对的选取对RTK平面测量结果的内外符合精度的影响,得出了如何使内外精度更符合的结论。  相似文献   

极坐标测量变形监测网稳定基准点组的检验     

孙立军  刘兴春  于兴超 《测绘信息与工程》2009,34(3):25-26

分析了全站仪极坐标测量变形监测网的特点,提出了利用坐标转换修正法进行稳定基准点组的检验方法,实现了变形监测网稳定基准点组的检验。  相似文献   

基于GCP库的星载SAR图像自动精校正   总被引：1，自引：0，他引：1  

许金萍  彭仲宇 《测绘科学》2009,34(5)

近年来,合成孔径雷达(SAR)技术已取得巨大进步,人们也越来越重视其潜在的应用前景。但是,雷达侧视成像性质和地形起伏的影响导致SAR图像的几何畸变非常复杂,大大影响了SAR图像的应用。几何精校正是SAR图像广泛应用的前提,但是校正过程中需要大量地面控制点(GCPs),以往的人工选点方法费时费力。本文提出了一种基于控制点自动匹配的控制点选点方法,用以提高点位精度和工作效率。该方法包括纠正区域GCP库的建立和GCP图像片的自动匹配。试验结果表明,该方法具有较好的应用价值。  相似文献   

基于空间分析的徐州市居民点分布模式研究   总被引：8，自引：1，他引：7  

闫庆武  卞正富  王桢 《测绘科学》2009,34(5)

居民点空间分布的研究是聚落地理学的主要内容之一,运用空间分析的方法研究居民点的分布能更准确地刻画出其空间分布的本质规律。本文根据2004年TM遥感图像和城市地图得到徐州市城乡居民点空间分布的信息,继而运用样方分析(QA)法、最近邻距离指数(NNI)、K(d)函数、热点探测技术(NNH)研究了徐州市居民点空间分布格局与模式。结果显示:徐州市居民点的空间分布具有明显的空间依赖性,总体上呈现出集聚分布的特点;随着研究尺度的变大,居民点空间分布的集聚性指数也增大;居民点空间分布的热点区域在微观尺度上具有空间随机性、在中观尺度上具有轴带延伸性、宏观尺度上具有面状集中性的特点。  相似文献   

一个从基于位置相关服务而收集的零星位置点中获取连续车辆轨迹的方法(英文)   总被引：1，自引：1，他引：0  

李响  张喜慧  林珲 《地球空间信息科学学报》2009,12(2):85-94

The paper proposes an economical and fast algorithm for deriving trajectories from sporadic tracking points collected in location-based services (LBS). Although many traffic studies or applications can benefit from the derived trajectories, the sporadic tracking points are always implicitly overlooked by most of existing map-matching algorithms. The algorithm proposed in this paper finds network paths or trajectories traveled by vehicles through augmenting GPS data with odometer data. An odometer can provide data of traveled distance which are compared with the lengths of candidate network paths in order to find the most approximate network path approaching the trajectory of a vehicle. Tracking points are classified into anchor points and non-anchor points. The former are used to divide trajectories, and the latter screen candidate network paths. An elliptic selection zone and a reduction process are applied to the selection of possible road segments composing candidate network paths. A brute-force searching algorithm is developed to find candidate network paths and calculate their lengths. A two-step screening process is designed to select the final result from candidate network paths. Finally, a series of experiments are conducted to validate the proposed algorithm. Supported by the National Natural Science Foundation of China (No.40701142), the Scientific Research Starting Foundation for Returned Overseas Chinese Scholars, Ministry of Education, China.  相似文献   

GPS双频精密单点定位软件及其精度分析     

阮仁桂  郝金明  吕志伟  秦士琨  刘勇 《测绘学院学报》2009,(4)

简要介绍了GPS双频精密单点定位数学模型及自主研制的精密单点定位软件。采用不同运动状态的实测数据进行静态、静态模拟动态和机载动态解算实验并从外符合的角度进行精度评估。实验结果表明:单天静态解精度达到cm级;动态解算精度达到cm-dm级。  相似文献   

A simplified yaw-attitude model for eclipsing GPS satellites   总被引：11，自引：2，他引：9  

J. Kouba 《GPS Solutions》2009,13(1):1-12

A simplified yaw-attitude modeling, consistent with Bar-Sever (1996), has been implemented and tested in the NRCan PPP software. For Block IIR GPS satellite it is possible to model yaw-attitude control during eclipsing periods by using the constant hardware yaw rate of 0.20°/s. The Block IIR satellites maintain the nominal yaw attitude even during a shadow crossing (Y. E. Bar-Sever, private communication, 2007), except for the noon and shadow midnight turn maneuvers, both of which can be modeled and last up to 15 min. Thus, for Block IIR satellites it is possible to maintain continuous satellite clock estimation even during eclipsing periods. For the Block II/IIA satellites, it is possible to model satisfactorily the noon turns and also shadow crossing, thanks to the permanent positive yaw bias of 0.5°, implemented in November 1995. However, in order to model the Block II/IIA shadow crossings, satellite specific yaw rates should be used, either solved for or averaged yaw-rate solutions. These yaw rates as estimated by the Jet Propulsion Laboratory (JPL) can differ significantly from the nominal hardware values. The Block II/IIA post-shadow recovery periods, which last about 30 min, should be considered uncertain and cannot be properly modeled. Data from post-shadow recovery periods should, therefore, not be used in precise global GPS analyses (Bar-Sever 1996). For high-precision applications, it is essential that users implement a yaw-attitude model, which is consistent with the generation of the satellite clocks. Initial testing and analyses, based on the IGS and AC Final orbits and clocks have revealed that during eclipsing periods, significant inconsistencies in yaw-attitude modeling still exist amongst the IGS Analyses Centers, which contribute to the errors of the IGS Final clock combinations.  相似文献   

LIDAR在林区送电线路设计中的应用可行性     

程永  陈功  胡勇  李光尧 《地理空间信息》2009,7(2):141-143

传统的航空摄影测量方式在林区送电线路中存在一些难题,机载激光雷达系统提供了一种新的解决途径。首先介绍了林区送电线路设计的难点,然后描述植被测量以及DEM获取的原理,最后展望了机载激光雷达系统在林区送电线路设计的应用前景。  相似文献