用改进的主成分分析法对东湖的水质污染进行评价   总被引：20，自引：0，他引：20  

姚焕玫  黄仁涛  甘复兴  刘洋 《武汉大学学报(信息科学版)》2005,30(8):732-735

从对逆指标进行线性变换、用对数化法对指标进行无量纲化及评价指标的选择等三个方面对传统主成分分析方法进行改进,并应用于东湖的水质污染质量评价中。与传统方法相比,本文方法更为合理地保留了原始指标矩阵中的信息,且第一主成分的贡献率有了显著的提高。评价过程全部用计算机实现,并将评价结果生成东湖水质污染专题图。  相似文献   

论多边形中轴问题和算法   总被引：9，自引：4，他引：9  

胡鹏  王海军  邵春丽  胡海 《武汉大学学报(信息科学版)》2005,30(10):853-857

比较了当前国内外GIS中和计算几何中关于多边形中轴的定义,讨论了它们的主要特点,指出多边形中轴应是到两个以上边距离相等点的轨迹,并据此分析了相应的各种算法和实际应用场合,提出了理论上较为严密、能够广泛满足实际应用需要的几何方法———点对序列法和地图代数多边形中轴法。  相似文献   

面向变化监控的动态电子地图设计   总被引：4，自引：0，他引：4  

艾廷华  朱熀  王洪 《武汉大学学报(信息科学版)》2005,30(10):858-861

以动态现象的表达、监控为主要任务的电子地图,具有四个功能:过程再现、实时跟踪、变化推演和变化模拟,分别对应时态特征上的过去式、进行式、将来式和虚拟语气。其设计原理与其他电子地图的差别表现为:地理背景底图的动态性,比例尺设计与时间有关,符号设计需扩充Bertin参量体系而引入动态参量,要顾及用户对变化过程的交互式控制。本文从地图设计角度讨论了这类地图的设计原理与方法,并应用到面向水路航务管理的电子航道图设计中,实现航标位置、工作状态的全天候远程监控。  相似文献   

电子地图数据管理系统的设计与实现     

胡大国  夏先荣 《国土资源信息化》2005,(3):24-28

电子地图数据的管理是一项细致、繁琐的基础性工作,对其管理是否科学、高效将直接影响数据的提供和服务,建立实用的数据管理系统辅助管理,以提高效率,从而提供更好的服务。本文从数据源、存储设备编号、系统构架、数据库设计、系统功能与应用等多个方面介绍电子地图数据管理系统的设计和实现。  相似文献   

Minimum conformal mapping distortion according to Chebyshev’s principle: a case study over peninsular Spain     

M. Bermejo  J. Otero 《Journal of Geodesy》2005,79(1-3):124-134

Defining the distortion of a conformal map projection as the oscillation of the logarithm of its infinitesimal-scale σ, Chebyshev’s principle states that the best (minimum distortion) conformal map projection over a given region Ω of the ellipsoid is characterized by the property that σ is constant on the boundary of that region. Starting from a first map of Ω, we show how to compute the distortion δ₀(Ω) of this Chebyshev’s projection. We prove that this minimum possible conformal mapping distortion associated with Ω coincides with the absolute value of the minimum of the solution of a Dirichlet boundary-value problem for an elliptic partial differential equation in divergence form and with homogeneous boundary condition. If the first map is conformal, the partial differential equation becomes a Poisson equation for the Laplace operator. As an example, we compute the minimum conformal distortion associated with peninsular Spain. Using longitude and isometric latitude as coordinates, we solve the corresponding boundary-value problem with the finite element method, obtaining δ₀(Ω)=0.74869×10⁻³. We also quantify the distortions δ_l and δ_utm of the best conformal conic and UTM (zone 30) projections over peninsular Spain respectively. We get δ_l=2.30202×10⁻³ and δ_utm=3.33784×10⁻³.  相似文献   

地图出版系统中公路类符号绘制的解决方法     

邓术军陈四清  刘宏林 《测绘学院学报》2005,22(2):134-135,138

在地图符号中公路类符号的绘制具有其特殊性，必须进行特殊处理才能正确显示。文中首先介绍了常见的两种处理方法，并分析了其存在的问题；然后针对地图出皈的要求，在全数字地图出版系统中，利用STL标准模板库技术，对公路要素进行批处理绘制，很好地解决了公路类符号的绘制问题。  相似文献   

网络地图人性化界面设计   总被引：10，自引：0，他引：10  

郑束蕾  陈毓芬 《测绘学院学报》2005,22(4):300-303,306

目前网络地图发展迅猛,但界面设计缺少理论指导,仍存在着许多问题.文中首先研究了网络地图的特点和界面内容,对目前网络地图界面设计中存在的突出问题进行归纳.接着提出了基于认知心理学理论的一般性网络地图界面设计原则.最后,对网络地图的用户层次进行分类,举例说明上述设计原则在人性化网络地图界面设计中的应用.  相似文献   

Subsidence hazard avoidance based on geomorphological mapping in the Ebro River valley mantled evaporite karst terrain (NE Spain)   总被引：1，自引：6，他引：1  

F. Gutiérrez-Santolalla  M. Gutiérrez-Elorza  C. Marín  C. Maldonado  P. L. Younger 《Environmental Geology》2005,48(3):370-383

In the valley of the Ebro River to the southeast of the city of Zaragoza (NE Spain), the dissolution of evaporite sediments (gypsum, halite and Na-sulphates) which underlie alluvial deposits gives rise to numerous sinkholes. These sinkholes are a potential hazard to human safety, particularly where they develop in a catastrophic way. Even slow-developing sinkholes are problematic, as they damage urban and agricultural infrastructure, necessitating costly repairs and vigilant maintenance. To assist in developing avoidance strategies for these hazards, the factors controlling sinkhole occurrence have been assessed using geomorphological maps produced from aerial photographs for 1956 and 1981. Important controls on sinkhole development are found to include underlying geological structure (manifest in preferred orientations of sinkholes on the azimuths N130-150E and N30-40E), and the presence of glauberite in the groundwater flow path, which apparently promotes accelerated gypsum dissolution. Perhaps surprisingly, alluvium thickness does not appear to significantly correlate with the density of sinkholes on the floodplain in this area. The maps for 1956 and 1981 reveal that both human activity and natural processes can serve to obscure the true density of sinkhole development. For instance, a large number of sinkholes which were conspicuous in 1956 have since been back-filled by farmers. In the most fluvially active zone of the Ebro valley (the meander belt), the relatively low density of sinkholes compared with adjoining zones suggests that subsidence is being masked by morpho-sedimentary dynamic processes (aggradation and erosion). Careful geomorphological mapping for different time periods yields a much more accurate impression of the frequency of sinkhole development than would be gained from surveying currently visible sinkholes in the area of interest.  相似文献   

Rhumb Lines and Map Wars: A Social History of the Mercator Projection by Mark Monmonier     

Dennis Fitzsimons 《The Professional geographer》2006,58(4):497-499

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城市多媒体电子地图系统探讨   总被引：2，自引：0，他引：2  

武钦琳 《现代测绘》2006,29(3):45-46

为及时反映城市信息的多媒体电子地图融合了数字制图技术、GIS技术、多媒体技术等多种高科技手段,为政府部门、公司企业、社会公众构建了一套便捷的、可视化的空间信息服务平台。介绍了多媒体电子地图的一些特点和重要性,并对多媒体电子地图的制作方法和设计理念等方面进行了探讨。  相似文献