Pattern based map comparisons   总被引：5，自引：0，他引：5  

Roger White 《Journal of Geographical Systems》2006,8(2):145-164

Map comparison techniques based on a pixel-by-pixel comparison are useful for many purposes, but fail to reveal important aspects of map similarities and differences. In contrast, pattern based map comparison techniques address the question of structural similarity, although with these approaches the comparison problem becomes open ended, since there is an unlimited number of ways to characterise a pattern. Two types of pattern based technique are used here to analyse the test sets of maps. The first, a fuzzy polygon based matching technique, focuses on the meso-scale aspects of pattern. It is based on the areal intersection of land use polygons on the two maps being compared. The areal intersection, areal complement, and polygon size values are fuzzified into an appropriate set of categories, a set of fuzzy inference rules is applied to derive memberships in local matching categories, and finally the local matching category memberships are defuzzified to yield local matching values for each land use polygon on the reference map. The second approach, fractal analysis, captures macro-scale or global qualities of the maps. Two measures are calculated here: the radial dimension and the cluster size—frequency dimension. The polygon matching approach provides only limited insight when applied to the case of the map set representing differences in classification. It proves much more effective when applied to the problem of change detection, revealing areas where the pattern has changed and giving local measures of the degree of change. The approach is particularly useful in the case where there is a considerable degree of random change at the pixel level, as changes in the underlying pattern are extracted from the noise, while pixel based approaches largely detect the noise.  相似文献   

GIS与Voronoi多边形在医疗服务设施地理可达性分析中的应用   总被引：5，自引：0，他引：5  

王远飞 《测绘与空间地理信息》2006,29(3):77-80

地理可达性是研究评价各种服务设施布局及其服务域的重要指标之一,空间距离、交通便捷性、出行成本等是可达性测度的重要因子。由于医疗设施等公共设施通常以服务的公平性和覆盖性为目标,因此可定义居民点到最邻近医院的距离为地理可达性的测度。在此基础上,作者提出了基于GIS与Voronoi多边形的地理可达性计算方法。这一方法不仅将地理可达性分析中的空间点对之间的距离计算简化为空间查询,方便了GIS应用,而且计算的Voronoi多边形在本质上就是最邻近意义上医院的服务域,即服务域内各居民点到该医院的距离就是最邻近距离。此外结合人口分布等属性数据,还可深入分析各医院的服务承载力,本方法为医疗设施等公共服务设施的规划决策提供了重要的工具。  相似文献   

面向对象的复杂多边形裁剪实现     

郭功举 《现代测绘》2003,26(4):12-14

本文在已有多边形裁剪算法的研究基础之上，提出了包含圆弧段的复杂多边型裁剪方法。该方法中的被剪切对象是较为复杂的几何实体，包括圆弧以及带有圆弧边界和带有洞的复杂多边形对象，其中剪裁窗口可以为凹多边形或凸多边形。  相似文献   

栅格数据矢量化及其存在问题的解决   总被引：5，自引：0，他引：5  

扶卿华  倪绍祥  郭剑 《现代测绘》2004,27(3):8-11

矢量结构和栅格结构是GIS的两种主要数据结构形式，而栅格数据的矢量化在GIS中具有十分重要的意义。本文在总结前人算法的基础上，以拓扑关系的原理为指导，提出了改进的栅格结构数据矢量化方法，即在提取结点和坐标点过程中同时提取水平和垂直的所有线段信息，以便于快速、有效地实现栅格数据的矢量化。此外，还采用动态打断和粗网格法等方法，解决了在栅格数据矢量化过程中经常出现的诸如多边形自交、岛等问题。  相似文献   

树结构及其在多边形内点匹配中的应用     

蔡先华 《测绘工程》1995,(4)

通过改变矢量多边形数据的存储结构,建立多边形内点匹配搜索树,根据搜索树的逻辑思维方式,提出一种多边形内点匹配程序的设计方法。应用这种方法,可减少内点匹配的时间。  相似文献   

A novel nonlinear solution for the polygon scaled boundary finite element method and its application to geotechnical structures     

《Computers and Geotechnics》2017

The polygon scaled boundary finite element method is semi-analytical and known for its high precision. However, the material nonlinearity cannot be maintained because this method uses an analytical solution in the radial direction. In this paper, a novel nonlinear algorithm is developed by introducing internal Gaussian points over a subdomain. The response of nonlinearity for a concrete-faced rockfill dam is modeled. The results correspond well with the results from finite element modelling, which demonstrates the method can be used to describe the nonlinear characteristics of geomaterials. Furthermore, this method offers promising flexibility for analyzing complex geometries without decreasing the precision.  相似文献