| GIS结点捕捉的广义算法及误差传播模型 |
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| 引用本文： | 刘文宝,夏宗国,崔先国.GIS结点捕捉的广义算法及误差传播模型[J].测绘学报,2001,30(2):140-147. |
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| 作者姓名： | 刘文宝 夏宗国 崔先国 |
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| 作者单位： | 1. 山东科技大学地球科学系
2. 美国麻省大学地球地理科学系 |
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| 基金项目： | 国家自然科学基金;49801016; |
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| 摘 要： | 根据最小二乘原理，本文提出了结点捕捉的一种广义算法，并建立了伴随的误差传播模型，针对位于模糊公差范围内待捕捉点组中各点坐标误差统计我的各种可能的特殊情况，进一步导出了相应的简化算法以及其误差传播模型，并从理论和数值模拟两方面系统地分析了结点坐标的相准确性一对捕捉结果的影响，理论推导表明，现有的GIS结点捕捉算法属广义算法的一种特殊情况，最后通过算例说明了广义算法和误差传播模型的实际应用前景。
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| 关 键 词： | 结点捕捉 模糊公差 广义算法 误差传播 GIS 地理信息系统 最小二乘法 |
| 文章编号： | 1001-1595(2001)02-0140-08 |
A New Generalized Algorithm of Node Snapping and a Universal Model of Error Propagating |
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| LIU Wen bao ,XIA Zong guo ,CUI Xian guo.A New Generalized Algorithm of Node Snapping and a Universal Model of Error Propagating[J].Acta Geodaetica et Cartographica Sinica,2001,30(2):140-147. |
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| Authors: | LIU Wen bao XIA Zong guo CUI Xian guo |
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| Institution: | LIU Wen bao 1,2,XIA Zong guo 2,CUI Xian guo 1 |
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| Abstract: | Data quality in GIS has been widely recognized as one of the most critical issues in GIS applications in recent years. There are numerous effective error models for managing error propagation in the process of data manipulation and analysis such as Boolean operations. However, there is a lack of models for dealing with errors in node snapping which is one of the basic operations in most GIS software packages such as ARCEDIT in ARC/INFO. Node snapping involves changing the position of points of a spatial feature so that points within a fuzzy tolerance of each other are connected automatically. Although this involves an adjustment of feature coordinates, in which the coordinates of the snapped node are simply the means of coordinates of two or more points, there are no quantitative techniques for assessing the spatial accuracy of the final node created by automatic snapping. In this paper, we propose a generalized algorithm of node snapping using the least square method and develop a universal model for handling error propagation related to node snapping. Simplified algorithms and models are derived for some special cases with different statistical characteristics of point errors within a fuzzy tolerance. The impact of statistical dependency of the existing points on the coordinates of the point obtained after snapping and the accuracy of the snapped point are examined through theoretical analysis and numerical simulation. Our results indicate that the level of influence depends on the coefficients of correlation between points involved in the snapping operation. We have shown theoretically that the snapping algorithm widely used in the past merely represents a special case of the generalized algorithm. Several examples are also provided to demonstrate the potential applications of the generalized algorithm and the related error model. |
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| Keywords: | node snapping fuzzy tolerance generalized algorithm error propagation |
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