Using Topological Relationships to Inform a Data Integration Process   总被引：2，自引：0，他引：2  

Sue Hope  Allison Kealy 《Transactions in GIS》2008,12(2):267-283

When spatial datasets are overlaid, corresponding features do not always coincide. This may be a result of the datasets having differing quality characteristics, being captured at different scales or perhaps being in different projections or datums. Data integration methods have been developed to bring such datasets into alignment. Although these methods attempt to maintain topological relationships within each dataset, spatial relationships between features in different datasets are generally not considered. The preservation of inter‐dataset topology is a research area of considerable current interest. This research addresses the preservation of topology within a data integration process. It describes the functional models established to represent a number of spatial relationships as observation equations. These are used to provide additional information concerning the relative positions of features. Since many topological relationships are best modelled as inequalities, an algorithm is developed to accommodate such relationships. The method, based on least squares with inequalities (LSI), is tested on simulated and real datasets. Results are presented to illustrate the optimal positioning solutions determined using all of the available information. In addition, updated quality parameters are provided at the level of the individual coordinate, enabling communication of local variation in the resultant quality of the integrated datasets.  相似文献   

土地调查中有关城镇与农村土地面积问题的研究     

吕长广  李淑青 《山东地质》2008,(9):36-38

第二次全国土地调查工作中,城镇与农村地区的土地面积在计算方法上有所不同：农村地区的土地面积是以椭球面为基准的面积,即球面面积;城镇地区的土地面积是以平面为基准的面积,即平面面积。二者之间存在差异并按一定规律变化,当调查区处于投影带边缘附近时,同一图斑的球面面积与平面面积之间的差异达到最大。由于采用不同的计算方法而导致面积数量的差异,在进行农村与城镇有关土地数据整合时会出现矛盾。为了建立城乡统一的土地管理信息系统,保证土地面积的一致性,应当采取相应措施消除二者之间的差异。  相似文献   

抗差最小二乘配置在数字化地图几何纠正中的应用讨论     

张亮 《测绘与空间地理信息》2008,31(2):145-148

抗差估计具有较好的抗拒异常观测值及粗差的能力,而最小二乘配置又能较好地处理系统误差,本文结合两者的优点,利用抗差最小二乘配置对数字化地图进行几何纠正,其中对协方差函数采用抗差拟合,得到了较好的结果。实验证明在GIS数据处理的扫描数字化地图几何纠正中,抗差最小二乘配置在抗拒异常值和处理系统误差方面优于单纯的最小二乘估计和单纯的最小二乘配置方法。  相似文献   

动态最小二乘支持向量机学习算法     

邓兴升  花向红 《武汉大学学报(信息科学版)》2008,33(11):1122-1125

针对大样本集的训练问题和动态训练样本的模型更新问题,提出了动态最小二乘支持向量机学习算法.该算法充分利用已建好的模型,逐渐加入新样本,并可删除位于任何位置的非支持向量,避免了矩阵求逆运算,保证了算法的高效率.大坝变形及电离层延迟两个时间序列的预报实例表明,该算法具有计算时间短、预报精度高的特点.  相似文献   

青藏高原东部及邻区地块现今运动特征     

《成都理工学院学报》2008,35(1):81-86

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城市大比例尺航测成图质量评定     

胡景海  钟生伟 《地理空间信息》2008,6(1):121-123

主要从大比例尺航测成图质量评定角度出发,提出了既要满足相应规范和用户要求,又要最大限度的发挥航测成图的优势,对产品质量做出公正、客观、正确的质量评价方法。  相似文献   

Comparison of structural and least-squares lines for estimating geologic relations   总被引：1，自引：0，他引：1  

Garnett P. Williams  Brent M. Troutman 《Mathematical Geology》1990,22(8):1027-1049

Two different goals in fitting straight lines to data are to estimate a true linear relation (physical law) and to predict values of the dependent variable with the smallest possible error. Regarding the first goal, a Monte Carlo study indicated that the structural-analysis (SA) method of fitting straight lines to data is superior to the ordinary least-squares (OLS) method for estimating true straight-line relations. Number of data points, slope and intercept of the true relation, and variances of the errors associated with the independent (X) and dependent (Y) variables influence the degree of agreement. For example, differences between the two line-fitting methods decrease as error in X becomes small relative to error in Y. Regarding the second goal—predicting the dependent variable—OLS is better than SA. Again, the difference diminishes as X takes on less error relative to Y. With respect to estimation of slope and intercept and prediction of Y, agreement between Monte Carlo results and large-sample theory was very good for sample sizes of 100, and fair to good for sample sizes of 20. The procedures and error measures are illustrated with two geologic examples.  相似文献   

北京城区广场分布、辐射及其文化生产空间差异浅析   总被引：1，自引：0，他引：1  

周尚意  吴莉萍  张庆业 《地域研究与开发》2006,25(6):19-23,32

广场是城市文化活动的重要载体，是城市中重要的文化生产空间。文章首先选择北京城区广场作为研究对象，首先调查了三级广场的分布状况，结合人口分布对广场分布进行了评价；其次调查了北京城区一个典型剖面上的4个广场，用格林方法确定了4个广场之间的空间分割点，并依据对广场活动者的调查，确定了每个广场的空间辐射范围的平面形态，从而确定了这4个广场文化生产空间的大致范围；第三，调查了广场的文化活动类型，并将活动类型的差异与城市文化空间的圈层进行了比较，从而解释了广场文化产生差异的原因。结论是，城市广场的建设属于城市实体空间建设的一种形式，它是人们自觉的、理性的行动，本着公平的原则建设广场，将使城市各个地方的居民具有依托广场开展文化活动的可能，并借助广场创造城市新的多元的文化。  相似文献   

New results on the resistivity structure of Merapi Volcano (Indonesia), derived from three-dimensional restricted inversion of long-offset transient electromagnetic data     

Michael Commer  Stefan L. Helwig  reas Hördt  Carsten Scholl  Bülent Tezkan 《Geophysical Journal International》2006,167(3):1172-1187

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Effect of lithospheric root on decompression melting in plume–lithosphere interaction models     

A. Manglik  U. R. Christensen 《Geophysical Journal International》2006,164(1):259-270

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