应用局部拓扑修改提高GIS路径分析精度

针对现有路径分析算法中道路节点与路径分析的起点、终点不一致而导致的分析误差问题,提出了一种应用局部拓扑修改的方法实时将路径分析的起点和终点作为结点插入拓扑网的路径分析算法,并采用动态修改网格索引的方法提高了节点与链的检索速度。经实验比较,该算法在很大程度上减小了分析误差,提高了算法的实用性,而时间复杂度与Dijkstra算法相比控制在10-1s内。     

基于Google Maps的路径分析方法研究

路径分析是GIS中的常用功能,它根据起点和终点的位置坐标,计算出一条可行路线表示在地图上,为大众用户的出行提供路线查询方法。本文在研究地名地址匹配技术与Google路线请求服务及Google地名服务基础上,结合两者优势,提出基于Google Maps的路径分析方法,并以实验进行论证,为在基于网络地图服务的WebGIS系统上实现路径分析功能提供一种新思路。     

基于栅格GIS的最优路径分析及其应用

最优路径分析是在移动的起点和终点之间寻找最佳的移动线路,对于旅行中的最短路径确定、工程设计中连接两地之间的线状设施(如输电线路、输油气管线等)的最佳布局规划等具有重要意义.阐述基于栅格的最优路径分析的基本原理,提出基于栅格的最优路径分析的一般过程,并以某地天然气管线最佳铺设线路为例说明基于栅格的最优路径分析的具体应用.     

最短路径分析在MapInfo中的实现

采用MapBasic语言,对MapInfo进行功能扩充,在MapInfo中实现最短路径分析。程序首先完善路网表结构,增加路网拓扑所必需的字段;然后进行路网拓扑,建立拓扑关系,并在此基础上采用Floyd算法实现最短路径分析。     

最短路径问题的一种改进算法

最短路径分析是ＧＩＳ最基本的网络分析功能。迪杰斯特拉算法是目前公认的较好的最短路径算法。文中从节约存储空间、提高运算速度出发, 在该算法的基础上, 采用点弧联合结构表达图, 提出节点的最大邻接深度概念及相邻节点低值传递方法, 实现最短路径的自动判断与提取, 并给出算法的实现方法。     

空间分析方法在道路网自动综合拓扑构建中的应用

在道路网的自动综合中,一般的方法都必须对道路网进行自动拓扑生成,建立起点、线、面之间的关系,以利于道路选取时网眼的分析和选取后的路径分析。本文考虑到数字地图的数据特点,在进行道路网自动拓扑过程中,对经常遇到的线状要素无法合理构面的问题进行分析并提出了合理的解决方法。方法中主要运用了缓冲区分析和叠置分析,通过把居民地层数据叠置到道路层数据进行联合分析,为道路网的自动选取构建出了正确的空间拓扑关系。     

基于连续极坐标的GIS路径汉语描述

GIS路径分析结果的汉语描述是指用人们日常生活中的语言和思维方式来描述路径分析结果,可以为用户提供描述清晰、便于理解的自然语言路径信息.提出了基于连续极坐标的GIS路径汉语描述法.该算法对GIS初始路径分析结果首先进行冗余节点的剔除处理,然后逐步建立连续极坐标系,求取节点极坐标、获取相关方向和距离信息,调用路径描述知识...     

一种利用分布式遗传算法的P2P负载均衡方法

采用Gossip协议,利用节点之间周期性的拓扑维护消息交换负载信息,提出了一种基于分布式遗传算法的负载均衡算法.在适应度的评估中,结合网络的物理拓扑,以最小化虚拟节点迁移开销,并利用P2P节点并行处理种群,以克服遗传算法计算量过大的缺点.实验结果表明,该算法在求解速度与质量上都取得了较大的改善.     

基于拓扑势的网络节点重要性排序及评价方法

基于数据场提出了基于拓扑势的节点重要性评价算法,该算法能更为精细、真实地反映节点的重要性.利用自然语言,建立了一个可以简练描述节点重要性"公理集",基于拓扑势的节点重要性评价比其他重要性评价方式更接近于该"公理集"的描述.最后运用基于数据场的层次聚类算法,对节点的重要性程度进行了定性划分.     

城市地图导航中多拓扑生成和实时动态路径分析

讨论在大型城市路网密集复杂的环境下，基于GPS车辆导航时拓扑的生成和动态路径分析。认为在专用的嵌入式环境下，实现实时动态路径分析，拓扑的建立必须按照分块和分级的方法。分块是为了解决动态调度的问题，分级是为了减少运算量，提高运算速度。同时对偏离航线时的路径分析提出了一种处理方法，在已经完成的导航仪中取得了理想的效果。     

阿克苏河-塔里木河水系水质污染遥感监测与评价

 采用Landsat TM数据分析了阿克苏河—塔里木河断面水质污染状况,通过波段的DN值和常规监测数据建立能反映水质状况的 污染物监测模型。结果发现,将2000年常规监测数据代入模型后,与遥感数据的结果基本吻合| 重建阿克苏河—塔里木河的连续水体 污染变化曲线,得出污染物浓度随着远离上游而增加。     

Monitoring drought dynamics in the Aravalli region (India) using different indices based on ground and remote sensing data

The hard-rock hilly Aravalli terrain of Rajasthan province of India suffers with frequent drought due to poor and delayed monsoon, abnormally high summer-temperature and insufficient water resources. In the present study, detailed analysis of meteorological and hydrological data of the Aravalli region has been carried out for the years 1984–2003. Standardised Precipitation Index (SPI) has been used to quantify the precipitation deficit. Standardised Water-Level Index (SWI) has been developed to assess ground-water recharge-deficit. Vegetative drought indices like Vegetation Condition Index (VCI) and Temperature Condition Index (TCI) and Vegetation Health Index (VHI) have been computed using NDVI values obtained from Global Vegetation Index (GVI) and thermal channel data of NOAA AVHRR satellite. Detailed analyses of spatial and temporal drought dynamics during monsoon and non-monsoon seasons have been carried out through drought index maps generated in Geographic Information Systems (GIS) environment. Analysis and interpretation of these maps reveal that negative SPI anomalies not always correspond to drought. In the Aravalli region, aquifer-stress shifts its position time to time, and in certain pockets it is more frequent. In comparison to hydrological stress, vegetative stress in the Aravalli region is found to be slower to begin but quicker to withdraw.     

使用FME与VBA提取机场方格网高程数据

因受机场工程设计软件的测量数据容量限制,基于LiDAR采集、点云分类后得到的地面点云数据LAS不能完整应用于目前设计软件进行设计计算。本文通过对拟选技术方案的筛选,提出了利用FME Workbench数据处理功能,结合VBA编程获取外部方格网平面数据的方法。该方法在FME Workbench中实现了地面点云数据构建TIN、采用逐点内插方法从TIN中提取方格网高程数据、等高线生成及相应图形处理与成果输出。最终通过实际算例证明了该方法的有效性。     

Landslide risk analysis between Giri and Tons Rivers in Himachal Himalaya (India)

The area around Sataun in the Sirmur district of Himachal Pradesh, India (falling between the rivers Giri and Tons; both tributaries of the Yamuna River) was studied for landslide vulnerability on behalf of the inhabitants. The study was made using extensive remote sensing data (satellite and airborne). It is well supported by field evidence, demographic and infrastructural details and aided by Geographic Information System (GIS) based techniques. Field observations testify that slope, aspect, geology, tectonic planes, drainage, and land use all influence landslides in the region. These parameters were taken into consideration using the statistical approach of landslide hazard zonation. Using the census data of 1991, vulnerability of the populace to the landslide hazard was accessed. As most of the infrastructure in the region is concentrated around population centres, population data alone was used for vulnerability studies.     

Gravity Changes Before Large Earthquakes in China: 1998-2005

Although it is well known that coseismic gravity changes take place during an earthquake, previous research has not yielded convincing evidence demonstrating that significant gravity changes occur before large earthquakes. Furthermore, even if we suspect that gravity changes occur before large earthquakes, we have yet to demonstrate how to consistently observe these changes for useful earthquake forecast that would bring benefits to society. We analyzed ground gravity survey data obtained in 1998, 2000, 200...     

GNSS系统及其技术的发展研究

阐述了国际上卫星导航系统的总体发展,对美、俄、欧、中的四大全球系统,以及相关的区域系统和增强系统进行了简单的介绍,研究分析了GNSS系统及其技术的发展趋势,同时分析了我国Compass全球系统面临的机遇和挑战,并提出了我国未来工作的建议.     

“4D”技术及其应用

介绍“４Ｄ”（即数字地面模型、数字正射影像、数字栅格地图和数字线划地图）系列产品的生产流程、关键技术、及其在耕地保护、防灾减灾救灾和城市规划等方面的应用方法。     

Virtual Australia: its key elements – know,think, communicate

Abstract

Virtual Australia is not a well-defined or agreed concept. This discussion paper conceptualises Virtual Australia as a ‘virtual [digital] model containing and representing all non-trivial objects and their contextual environment – from blue sky to bedrock – in real world Australia’. It describes a scenario for Virtual Australia, one or two decades from now, in which the locations and conditions of non-trivial objects and their environment are updated automatically through a combination of remote sensing and wireless communication technologies in support of a ‘Supranet’. It then examines the concept of the ‘Supranet’ – a pervasive information network based largely on wireless technology linking the physical world to a virtual model in real time – and develops and discusses three principal characteristics of the Supranet: the ability to have or collect specific information (know); the ability to process information (think); and the ability to communicate that information. If, in the near future, any or all non-trivial devices are to some extent able to know, think and communicate, the potential for object autonomy will be realised.     

自动车辆定位导航系统中传感器的误差分析

对国界定位导航系统中几种常见的辅助传感器所产生的误差进行了分析，导出了不同传感器的误差模型。这些误差模型是估计车辆位置的扩展卡尔曼滤波器的基础，同时也为选择适当的传感器提供了理论根据。