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Spatial conflicts may occur when map data are displayed at a scale smaller than that of the source map. This study applies the displacement operator in cartographic generalization to resolve such spatial conflicts and to improve the clarity and legibility of map. The immune genetic algorithm (IGA) is used in this study for buildings displacement to solve conflicts. IGA is based on the genetic algorithm (GA) and employs the self‐adjusting mechanism of antibody concentration to enhance population diversity. Meanwhile, the elitism retention strategy is adopted in IGA to guarantee that the best individual (antibody) is not lost and destroyed in the next generation to strengthen convergence efficiency. The compared experiment between IGA and GA shows that the displacement result produced by IGA performs better than GA. Finally, in order to make the displaced map more attractive to cartographers, two constraints – the building alignment constraint and building tangent relation constraint – are applied in IGA to restrict the buildings’ displacement. The same experimental data are adopted to prove that the improved IGA is useful for maintaining the two constraints. 相似文献
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The displacement operator is an important and still a hot topic in map generalization. In the generalization product, symbols
must be unambiguous and easily perceived and readily understood, which makes space competition among features an important
obstacle in the process of map objects displacement. Space conflict between objects, through propagation process, may be spread
and more objects may drift into it. In order to maintain symbols equilibrium and spatial relationship between objects, some
unimportant symbols or parts of symbols should be distorted under constraints according to visual graphic resolution thresholds
to figure out space competition among map features. Three constraints including position, legibility and characteristics are
important for the maintenance of symbols equilibrium and spatial relationship, which are discussed in this paper. The skeleton
is introduced to represent area objects figure characteristic, in which an area object can be separated to parts hierarchically
according to their importance in the construction. Then, the finite element method is applied to the map objects’ displacement
and distortion, in which a strategy for the parameters of finite element method is discussed.
Supported by the National Science Foundation of China (No.40401050), the Leading Academic Discipline Project of Shanghai Educational
Committee (No.J50104), the Science Foundation of Shanghai Education Department (07ZZ09). 相似文献
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Tinghua Ai 《地球空间信息科学学报》2010,13(2):85-92
The progressive transmission of map data on the World Wide Web provides the user with a self-adaptive strategy to access remote
data. It not only speeds up the web transfer but also offers an efficient navigation guide for information acquisition. The
key technology in this transmission is the efficient multiple representation of spatial data and pre-organization on the server
site. This paper aims at progressive transmission investigating some constraints from three aspects: data organization on
server site, data control in the transmission process and data restore after reaching the client. Two strategies, namely on-line
map generalization and off-line map generalization, are examined respectively for this kind of progressive transmission. 相似文献
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地图综合中,建筑物群的排列结构是需要重点考虑的因素。当不同排列的子建筑物群之间存在空间图形冲突时,这些建筑物群的综合就显得更为复杂。直线排列建筑物群的综合在大比例尺地形图上以典型化操作为主。本文提出一种相互之间存在潜在空间图形冲突的多个直线排列建筑物子群的渐进式典型化方法,渐进式地处理多个直线排列建筑物子群之间的空间图形冲突,保留建筑物群重要的直线排列结构;以建筑物表达的视觉图形约束为限制条件,自动确定典型化后的建筑物位置、形状、大小和方位。本文还研究了基于建筑物群空间邻近图的直线排列建筑物子群的自动识别方法,分析了这些直线排列之间的邻近关系和相交关系。最后,以1：5000地图上的建筑物群综合为1：25 000为试验对象,验证了所提出算法的可用性和有效性。 相似文献
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形状分析和形状识别是地图综合的重要内容之一,地图综合中需要对地理要素进行结构的识别,包括对要素的分布模式和形状特征进行分析,以便获取地理要素和现象的分布规律,制定综合的总体策略。其二,同一要素在不同尺度的表达中应保持形状的主体轮廓的一致性,这需要在综合算法中顾及形状的保真问题。其三,在地图综合的结果评价中,形状相似性是其重要的指标。地图是现实世界的抽象反映,没有形状的一致性人们很难将地图中的要素与真实的地理要素建立对应关系。但形状识别属于认知领域的范畴,具有很强的主观性和不确定性。本文就形状分析和识别在地图综合中的应用进行了探讨。 相似文献
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ABSTRACTOn nautical charts, undersea features are portrayed by sets of soundings (depth points) and isobaths (depth contours) from which map readers can interpret undersea features. Different techniques were developed for automatic sounding selection and isobath generalization. These methods are mainly used to generate a new chart from the bathymetric database or from a larger scale chart through selection and simplification. However, a part of the process consists in selecting and emphasizing undersea features formed by groups of soundings and isobaths on the chart according to their relevance to maritime navigation. Hence, automation of the process requires classification of features and their generalization through the application of a set of operators according not only to geometric constraints but also to their meaning.The objective of this work is to conceive a multi-agent system (MAS) for nautical chart generalization that is driven by the knowledge on the generalization process and the undersea features and their relationships. First, this work provides a feature-centered ontology modeling of the generalization process. Then, the MAS structure is introduced where agents access cartographic knowledge stored in the ontology. The MAS makes use of measure algorithms to evaluate constraint violations on the chart in order to decide which generalization operators to apply. The whole model has been implemented to provide generalization plans on a real case study. 相似文献
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作为土地利用图综合的一个重要组成部分，线状要素综合质量的好坏对于有效提高自动制图综合的正确率具有重要意义。本文基于模糊综合评判理论对土地利用图中线状要素的综合进行了质量评价。首先，基于制图综合约束，确定评价指标体系，组成评价因素集；其次，在确定评判集和权重集的基础上，建立线状要素综合质量评价模型；最后，利用试验验证了评价方法的有效性。该研究为客观评价土地利用图中线状要素的综合质量提供了新的思路。 相似文献
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针对建筑群自动综合结果质量评价问题,该文提出一种建筑群多尺度表达中空间相似度计算模型。从地图综合质量评价的角度,立足地图综合的3个约束,即图形约束、拓扑约束、结构约束,分别计算了图形相似度、拓扑相似度、结构相似度,并对以上各相似度作了适当的权重分配,计算建筑群目标的整体相似度。最后,通过实验验证了本文相似度计算方法的正确性、可行性。 相似文献
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地图综合的本质是一种空间相似变换,制图者在相似原则的指导下实施概括,读图者从包含相似性的地图中形成心象地图、重构现实世界。因此,多尺度地图空间中的相似关系研究非常重要。然而,由于相似的可计算性差,且其计算的目的在于揭示更深层次的信息,地图综合中相似关系尤其是语义相似关系的研究相对较少。针对这一问题,本文以语义功能区约束下的大比例尺街区式居民地合并（1∶1750至1∶4000）为例,基于匹配距离模型计算建筑物合并中的语义相似度,得到语义相似度在关键比例尺节点的值,并对结果进行分析、评价。试验表明,语义功能区约束下的建筑物合并符合读图者的地图认知需求,本文所述方法有助于地图更好地发挥信息传输载体的作用。 相似文献
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基于有效约束的附不等式约束平差的一种新算法 总被引：2，自引：2，他引：0
不等式约束是客观实际中普遍存在的一种约束,但目前大地测量数据处理领域并没有成熟、完整并被普遍接受的处理理论和方法。首先简要总结附不等式约束平差的各种方法及其存在的问题。然后对现有测量平差中附有等式约束的平差模型进行扩展,提出一种新的处理附有线性约束(包括等式和不等式约束)的平差方法。该方法在有效约束概念下,通过库恩-塔克条件来寻找有效约束条件,把不等式约束平差问题转化为我们熟知的等式约束平差问题,因此实现解向量与观测向量之间的显式表达。最后,用一个数值算例验证新方法的可行性,同时算例分析表明:用等式约束代替有效约束或集成约束进行平差计算,能得到正确的平差结果,但得不到正确的精度评定结果。 相似文献
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在地图综合中,许多建筑多边形化简的方法都是针对于直角多边形的,建筑多边形的直角化也是地图数据在进入GIS之前对数据完整性检验的必经过程.本文介绍了一种利用条件极值来计算直角地物中各点坐标改正数的方法.该方法成功用于大比例综合缩编软件GenTool,并获得了满意的效果. 相似文献
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结合生产实际,提出了1∶500-1∶2 000地形图缩编处理方法.在清华山维EPS 2008地理信息工作站上定制开发了1∶500-1∶2000地形图缩编平台,对现有1∶500 EDB数据源进行图元对照转换和制图综合完成复杂的地形图的编辑工作,其中制图综合采用全自动批处理、人机交互式,以及手工编辑相结合的处理模式. 相似文献