共查询到20条相似文献,搜索用时 828 毫秒
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基于规则知识的空间推理研究 总被引:5,自引:0,他引:5
在一般空间推理的基础上 ,提出了空间推理扩展 ,即基于规则知识的空间推理。该方法结合了人工智能的基本原理 ,继承并发展了空间推理的方法学 ,其推理过程建立在空间知识与模型集成的基础上 ,以规则知识为推理控制 ,因而更符合实际 ,具有更大的灵活性。实例验证了本方法的正确性。 相似文献
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3D-GIS中方向关系描述及其推理 总被引:2,自引:0,他引:2
方向关系是描述一个物体与另一个物体的相对位置关系。现有文献主要研究二维空间方向关系的描述和定性推理,二维空间中方向关系的描述和推理相对比较完善。本文采用投影方法给出三维空间方向关系描述模型,研究了单方向关系的推理,在此基础之上给出了单方向与多方向关系的定性推理,以及多方向关系与多方向关系间的定性推理。最后研究单方向关系定性推理的一些规律。 相似文献
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GIS中拓扑和方向关系推理模型 总被引:14,自引:6,他引:14
当今GIS在空间分析、建模和推理方面的能力极其有限,究其原因,现有GIS空间数据表达不直接支持推理运算,空间关系推理模型相互独立且运算复杂,准确性不高。本文在深入研究现有空间拓扑关系和方向关系推理模型的基础上,基于Cobb的空间拓扑关系模型的基本思想,建立了拓扑关系矩阵TopX2×2、TopY2×2和方向关系矩阵Dir3×3并将拓扑和方向关系推理计算统一到空间目标的MBRs(MinimumBoundingRectangles)的比较运算上来,达到了简化推理运算和统一建模实现拓扑和方向关系的联合推理,丰富了空间关系推理的语义,提高了推理的准确性。 相似文献
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三维体目标间拓扑关系与方向关系的混合推理 总被引:1,自引:1,他引:0
重点研究了三维空间中拓扑关系和方向关系间的混合空间关系推理。用Allen区间关系对描述基于投影的空间划分方法得到的方向区域和用九交矩阵描述的拓扑关系,用定义法研究混合空间关系推理,推理结果用组合推理表表示。 相似文献
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八方向模糊不均匀划分及参考点位误差所致不确定性分析 总被引:1,自引:0,他引:1
方向概念的模糊性和空间数据固有的不确定性导致了方向关系的复杂性,在空间关系描述和推理研究中需要考虑空间数据的不确定性和方向概念的模糊性。在四方向模型中各方向片是等角划分;在八方向模型中4个主要方向片各占60°,4个次要方向片各占30°。利用区间二型模糊集理论建立了顾及参考点点位误差的八方向模糊不均匀划分模型,基于区间二型模糊集讨论了方向主隶属度成员函数和隶属度的不确定性。对比分析了八方向模糊不均匀划分模型与锥形模型的区别,讨论了具有点位误差的参考点与线和多边形的方向关系计算过程,通过两个实例分析了该模型的特点和点与多边形方向关系的确定方法。 相似文献
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基于VRS的GPS测量误差分析 总被引:1,自引:0,他引:1
系统误差包括卫星轨道误差、卫星钟差、接收机钟差及大气折射误差等。是GPS测量的主要误差源。但系统误差通常可以采用适当的方法来减弱或消除,如建立误差改正模型对观测值进行改正,或选择良好的观测条件,采用适当地观测方法,进行线性差分等.本文介绍了基于VRS的GPS测量要解决的一个主要问题即在系统运行中产生的各种误差进行改正,使之减小或者消除。并就影响VRS精度的各种误差予以分析 相似文献
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从数字高程模型(DEM)传递误差、基于中误差的DEM误差模型及其主要问题、DEM误差分布实验和DEM内插误差新认识几个方面分析了当前DEM误差研究的主要进展,用"中误差"讨论DEM传递误差是建立在测量误差传递理论基础之上的,但沿用"中误差"来讨论DEM内插模型逼近误差和DEM整体误差却缺乏理论依据。DEM误差分布的空间相关性实验对DEM中误差评价法所应具备的随机误差性提出质疑,却可以用基于逼近理论的DEM内插模型来解释,说明用逼近误差理论研究DEM内插误差的途径是正确、可行的。 相似文献
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高精度海洋重力仪系统误差建模研究 总被引:1,自引:0,他引:1
导出高精度海洋重力仪系统的速度控制方程、角速度控制方程和纬度控制方程。以高精度海洋重力仪系统中平台的横倾角、纵倾角、运载体的东向速度误差、北向速度误差和运载体的纬度误差为变量,导出高精度海洋重力仪系统误差模型,并进行了系统误差仿真实验.理论分析和仿真实验表明:高精度海洋重力仪的系统误差形成过程分为误差积累、误差衰减和误差稳定三个阶段;0~1800 s是系统误差积累阶段,最大系统误差约为3.0×10-6m/s2;由于水平阻尼网络的作用,从1800~3000 s是仪系统误差衰减阶段;3000 s以后,系统误差进入稳定阶段,仿真4000 s时,系统误差约为2.246×10-6m/s2。 相似文献
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A general framework for error analysis in measurement-based GIS Part 3: Error analysis in intersections and overlays 总被引:3,自引:1,他引:2
This is the third of a four-part series on the development of a general framework for error analysis in measurement-based geographic information systems (MBGIS). In this paper, we study the characteristics of error structures in intersections and polygon overlays. When locations of the endpoints of two line segments are in error, we analyze errors of the intersection point and obtain its error covariance matrix through the propagation of the error covariance matrices of the endpoints. An approximate law of error propagation for the intersection point is formulated within the MBGIS framework. From simulation experiments, it appears that both the relative positioning of two line segments and the error characteristics of the endpoints can affect the error characteristics of the intersection. Nevertheless, the approximate law of error propagation captures nicely the error characteristics under various situations. Based on the derived results, error analysis in polygon-on-polygon overlay operation is also performed. The relationship between the error covariance matrices of the original polygons and the overlaid polygons is approximately established.This project was supported by the earmarked grant CUHK 4362/00H of the Hong Kong Research grants Council. 相似文献
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多波束测深数据系统误差的削弱方法研究 总被引:1,自引:0,他引:1
在多波束数据处理中,系统误差一般很少被顾及,部分文献采用两步滤波法削弱了系统误差的影响,但所建模型的可靠性较差。半参数(非参数)法在系统分析了测深数据系统误差来源以及各误差源间相互比例关系的基础上,对系统误差进行分解,确定系统误差各贡献成分的函数模型;根据估计点位,结合已确立的模型,计算各贡献成分对系统误差的贡献量;综合各贡献量,获得估计点深度的系统误差,进而在原始深度数据中消除系统误差的影响。 相似文献
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Studies the spatial patterns of location error and of classification error in spatio-temporal datasets, assess the role of environmental factors in determining error rate and pattern, and test for possible correlation within and between these error types in space and time. A multiple regression was used to determine the effects of local environmental factors (topography, vegetation cover) on each error type. Topographic structure and vegetation cover had significant effects on location error, where larger error was associated with north-facing aspects, steeper slopes and woody vegetation cover. Classification error was also affected by topography, and vegetation cover. Slope was the major factor that affected classification quality. Strong correlation was found between error in different time steps, for both error types. Correlation between these two error types in the same time step was much smaller and in most cases insignificant. 相似文献
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Eryong Liu 《制图学和地理信息科学》2016,43(4):321-327
This article presents a new development in measuring the positional error of line features in Geographic Information Systems (GIS), in the form of a new measure for estimating the average error variance of line features, including line segment, polyline, polygon, and curved lines. This average error measure is represented in the form of a covariance matrix derived by an analytical approach. Corresponding error indicators are derived from this matrix. The error of line features mainly results from two factors: (1) an error propagated from the original component points of line features and (2) a model error of interpolation between these points. In this study, a method of average error estimation has been derived regarding the first type error of line features that are interpolated by either linear or cubic interpolation methods. The main contribution of the research is the provision of an error measure to assess the quality of spatial data in application settings. The proposed error models for estimating average error variance of line features in a GIS are illustrated by both simulated and practical experiments. The results show that the line accuracy from a linear interpolation is better than a line interpolated using a cubic model. 相似文献