A General Framework for Using Aggregation in Visual Exploration of Movement Data     

《The Cartographic journal》2013,50(1):22-40

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一种分布式空间数据的服务聚合模型     

丰荣祥  谢忠  罗显刚 《测绘科学》2013,38(1):44-46

数据源的异构、GIS服务规范的自定义以及分布式存放等问题制约了空间信息的广泛共享和应用。本文基于空间信息共享平台建设,围绕服务动态聚合的思想,结合OGC的标准规范和技术思想,在具有REST风格的GIS服务的基础之上,提出了一个服务聚合模型,通过该模型实现了分布式存放的异构瓦片数据的无缝集成显示以及网络要素服务的功能共享。  相似文献   

利用粒子群算法的小波神经网络探讨     

甄宗坤  林子晔  郇小龙  朱军平 《测绘科学》2013,38(3):172-174

小波神经网络(WNN)具有较强的逼近和容错能力,并具有良好的收敛性和鲁棒性。然而其网络收敛速度慢、搜索成功率低和易陷入局部极小值等缺点使得传统的小波神经网络难以得到广泛应用。本文介绍一种基于粒子群(PSO)算法的小波神经网络,其通过利用种群间信息共享进行寻优,以获得结构化的神经网络,克服了传统小波网络的诸多缺点,结合工程实例,检验了其具有较好的适用性和可靠性。  相似文献   

Spatial object aggregation based on data structure,local triangulation and hierarchical analyzing method     

Liu Yaolin  Martien Molenaar  Menno-Jan Kraak  Liu Yanfang 《地球空间信息科学学报》2013,16(1):44-54

This paper focuses on the methods and process of spatial aggregation based on semantic and geometric characteristics of spatial objects and relations among the objects with the help of spatial data structure (Formal Data Structure), the Local Constrained Delaunay Triangulations and semantic hierarchy. The adjacent relation among connected objects and unconnected objects has been studied through constrained triangle as elementary processing unit in aggregation operation. The hierarchical semantic analytical matrix is given for analyzing the similarity between objects types and between objects. Several different cases of aggregation have been presented in this paper.  相似文献   

一种可配置的富客户端地图聚合应用模式研究     

杨祖虎  石伟伟 《测绘与空间地理信息》2013,(Z1):11-14

Web GIS技术的诞生给GIS应用开发带来了前所未有的革新,尤其是富客户端地图聚合技术的产生,给基于Web的GIS应用带来了很大的灵活性。传统的Web GIS应用通常都是按照特定客户的数据环境和应用需求进行定制开发的,为了客户操作的方便而在应用程序中对数据结构及其内容进行了固化,具备了方便地满足该客户在特定时间的需求的能力。然而,这类应用往往很难在无须更新代码的情况下满足用户随着时间的推移而需要加入新的地图数据或业务数据、配置新的专题应用地图的需求,尤其无法满足在无须调整代码的情况下将同样的程序应用在一个需求相似、数据不同的新用户那里。本文介绍了一种新型的可配置扩展的富客户端地图聚合应用模式设计及其应用情况。结果表明,这种新型的应用模式充分发挥了富客户端地图聚合技术的优势,结合基于统一数据库设计的后台配置管理系统,完全能够在零编程的情况下快速地响应客户对于应用新数据的需求,以及将同一应用快速移植、应用到新用户场景的需求。  相似文献   

甘肃敦煌西湖荒漠-湿地生态系统优势植物种群分布格局及种间关联性   总被引：2，自引：1，他引：1  

张瑾  陈文业  张继强  赵明  吴三雄  王志广  袁海峰  窦英杰  康建军 《中国沙漠》2013,33(2):349-357

基于25个样地、375个样方和150条样线的调查资料,采用扩散系数(C)、负二项参数(K)、平均拥挤度(m*)、丛生指标(D、聚块性指标(PI)、Green指数(GI)、Cassie指标(GA)和Moristia指数(Ⅰδ)等8个指标以及方差比率(VR)法,对甘肃敦煌西湖荒漠-湿地生态系统优势植物种群的空间分布格局、聚集强度和种间总体关联性进行了研究.结果表明:①研究区8种优势种群均为聚集分布(p＜0.01).其中,多枝柽柳群落、多枝柽柳沙包群落和胡杨群落均具有较高聚集程度,而疏叶骆驼刺群落和芦苇群落均具有较低聚集程度.②研究区优势种群中灌(乔)木层均为聚集分布(p＜0.05).③研究区优势种群在各海拔梯度上均为聚集分布(p＜0.05).随海拔梯度的增加,种群聚集强度增加,且种群聚集程度变化较为平缓.④研究区植物群落中,灌(乔)木层主要种群的种间联结表现为显著的正关联,乔灌草和草本层的主要种群的种间联结表现为显著的负关联.应用2×2联列表x2统计量、联结系数(AC)和共同出现百分率(PC)等方法,综合分析了敦煌西湖主要种群的种间联结显著性和关联强度.结果表明:研究区大多数种群种间关联程度不显著(p＞0.05),不关联的种对数明显要多于显著关联种对数,显著负关联的种对数多于正关,说明种群对生境和资源要求不一样,与总体种间相关性检验的方差比率VR值的结果一致,群落中优势物种处于不稳定阶段.  相似文献   

巴丹吉林沙漠沙山粒度组成与沙山地貌分带   总被引：1，自引：0，他引：1  

邵天杰  赵景波  董治宝 《山地学报》2013,31(4)

为查明巴丹吉林沙漠东南部沙山的成因与发育机制,在沙山密集分布的中心地区选择典型高大沙山作为研究对象,将单个沙山的物质组成与地貌分带相结合进行系统、定量的研究.通过粒度分析获得了沙山不同剖面、不同部位沉积物的粒度组成和各粒级含量的变化等数据,并进一步探讨了粒度组成和含量变化与沙山地貌分带、形成风动力条件之间的相互关系.得出以下主要结论:1.巴丹吉林沙漠沙山粒度组成为粗粉砂、极细砂、细砂、中砂、粗砂.其中细砂含量最高,中砂、粗砂次之,极细砂和粗粉砂含量均较少.2.沙山迎风坡表层沉积物的粒度比迎风坡下层和背风坡表层要粗,其搬运介质的平均动能也最大.3.从沙山坡脚到坡顶粒度组成均呈现由粗变细的趋势,这是由它们的形成过程和受到的动力作用存在差异决定的.4.沙山迎风坡不同部位的坡度、沙丘类型与分布在纵向上存在明显差异,可将其分为风蚀粗化的平沙洼地带、稀疏简单的新月形沙丘或沙丘链带、密集叠置的新月形沙丘及沙丘链带、陡峭的主峰带等4个地貌带.5.组成沙山的风沙物质不是一次搬运到达沙山中上部的,而是经过了多次的风力搬运阶段才达到的.  相似文献   

Area aggregation in map generalisation by mixed-integer programming     

Jan-Henrik Haunert  Alexander Wolff 《International journal of geographical information science》2013,27(12):1871-1897

Topographic databases normally contain areas of different land cover classes, commonly defining a planar partition, that is, gaps and overlaps are not allowed. When reducing the scale of such a database, some areas become too small for representation and need to be aggregated. This unintentionally but unavoidably results in changes of classes. In this article we present an optimisation method for the aggregation problem. This method aims to minimise changes of classes and to create compact shapes, subject to hard constraints ensuring aggregates of sufficient size for the target scale. To quantify class changes we apply a semantic distance measure. We give a graph theoretical problem formulation and prove that the problem is NP-hard, meaning that we cannot hope to find an efficient algorithm. Instead, we present a solution by mixed-integer programming that can be used to optimally solve small instances with existing optimisation software. In order to process large datasets, we introduce specialised heuristics that allow certain variables to be eliminated in advance and a problem instance to be decomposed into independent sub-instances. We tested our method for a dataset of the official German topographic database ATKIS with input scale 1:50,000 and output scale 1:250,000. For small instances, we compare results of this approach with optimal solutions that were obtained without heuristics. We compare results for large instances with those of an existing iterative algorithm and an alternative optimisation approach by simulated annealing. These tests allow us to conclude that, with the defined heuristics, our optimisation method yields high-quality results for large datasets in modest time.  相似文献   

Detecting negative spatial autocorrelation in georeferenced random variables     

Daniel A. Griffith  Giuseppe Arbia 《International journal of geographical information science》2013,27(3):417-437

Negative spatial autocorrelation refers to a geographic distribution of values, or a map pattern, in which the neighbors of locations with large values have small values, the neighbors of locations with intermediate values have intermediate values, and the neighbors of locations with small values have large values. Little is known about negative spatial autocorrelation and its consequences in statistical inference in general, and regression-based inference in particular, with spatial researchers to date concentrating mostly on understanding the much more frequently encountered case of positive spatial autocorrelation. What are the spatial contexts within which negative spatial autocorrelation should be readily found? What are its inferential consequences for regression models? This paper presents selected empirical examples of negative spatial autocorrelation, adding to the slowly growing literature about this phenomenon.  相似文献   

WEATHERING PIT CHARACTERISTICS AND TOPOGRAPHY ON STONE MOUNTAIN,GEORGIA     

Thomas R. Paradise  Zhi-Yong Yin 《自然地理学》2013,34(1):68-80

A detailed analysis of weathering-pit distribution on Georgia's Stone Mountain granite dome reveals a complex relationship between pit size and density, compared with slope aspect and angle. The uniform nature of the lithology provides an ideal natural laboratory for the analysis of weathering pits. Through the random establishment of 32 dome-encircling, ten-by-ten meter study plots within an elevational range from 610 to 650 meters, the distribution, size, aspect, slope and lithology of pit features were mapped, measured, and analyzed. Thematic maps were used in the visual representation of pit distribution and dimension data. Correlation coefficients, ANOVA, and multiple regression analyses were utilized to determine the relationships of these variables. Pits showed a dimensional and density increase toward a southwestern aspect as well as a dimensional and density increase with decreasing slope angle. Greatest pit dimensions were found at approximately the 200° N azimuth. These findings lead the authors to conclude that insolation weathering may be a more important process in granite pit formation on Stone Mountain than commonly believed because afternoon temperature maxima accelerate weathering through increased chemical constituent dissolution and/or crystal constituent disintegration. [Key words: weathering pits, gnammas, granite weathering, Stone Mountain.]  相似文献