共查询到20条相似文献，搜索用时 125 毫秒
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分析了常规压缩算法(如Douglas-Peucker算法)压缩无拓扑多边形数据会产生公共边界不一致现象,认为出现此现象的原因是多边形公共边界的压缩起始点选择不一致,进而提出了一种新的基于约束点的无拓扑多边形数据压缩算法.算法原理包括:首先将多边形公共边界的两个端点作为约束点处理,使得多边形从约束点处逻辑上分成几段;然后利用常规压缩算法进行分段压缩,使每一多边形公共边界的压缩初始点一致,从而保证了无拓扑多边形数据的一致性压缩;最后大量试验验证了此算法的有效性. 相似文献
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GIS中多边形图拓扑信息生成的数学基础 总被引：19，自引：2，他引：19
本文从ＧＩＳ应用角度给出了多边形图的定义，简述了多边形图的性质；论述了多边形图拓扑信息自动自下而上的数学原理及拓扑信息正确性的检验准则。 相似文献
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正确无误的弧段拓扑信息有利于提高空间信息查询、检索和分析等操作的效率,简化程序设计方法.在弧段拓扑处理过程中,某个多边形是其所有弧段的左多边形还是右多边形,一般难以判断.就如何判断弧段的左右多边形方法进行讨论,并给出一个简便、快捷的处理方法. 相似文献
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任意多边形的裁剪算法在地图制图过程中和GIS空间数据处理中具有重要意义。本文依照Weiler-Atherton算法,在不带内边界的无拓扑关系任意多边形裁剪算法基础上,论述了带内边界的无拓扑关系任意多边形裁剪算法的步骤和裁剪子区域多边形的追踪过程,为研究更为复杂的任意多边形裁剪算法提供了思路,使Weiler-Atherton算法应用更为广泛。 相似文献
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在保证多边形之间拓扑关系完整的基础上,分别使用垂距限值法和Douglas-Peucker算法对多边形形状进行了简化,同时从多边形常规参数以及相似度等方面对简化后多边形的质量进行了评价。实验结果表明Douglas-Peucker算法的简化效果较好。 相似文献
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AutoCAD中过近顶点的自动溶合 总被引：1，自引：0，他引：1
在基于AuotoCAD的图形中,采用多边形过近顶点的自动溶合方式,可有效地消除多边形的拓扑问题,提高内业数据处理速度和数据质量. 相似文献
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《制图学和地理信息科学》2013,40(1):70-74
The peak-pit-pass polygon line-shading procedure partitions any concave polygon into a series of triangles and trapezoids that are shaded independently. These convex subpolygons are identified by processing each vertex of the polygon outline in descending rank order. Alternative actions are initiated whenever a local maximum (peak), a local minimum (pit), or neither (pass) is encountered. Being relatively insensitive to the topology of the polygon and to the density of shade lines while minimizing storage and time requirements, this algorithm achieves a balance between efficiency and flexibility. 相似文献
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Parvaneh Nowbakht Lilian O'Sullivan David P. Wall Paul Holloway 《Transactions in GIS》2023,27(1):84-104
Geoprivacy protection is a significant concern when sharing data. To support sustainable land management by leveraging existing agricultural data, research is needed to identify how the polygon nature of static field parcels can be obfuscated to allow data sharing among individuals and organizations. In this study, five adaptive polygon-based obfuscation methods including PN*Rand, PDonut-k, PDensity-k, PAHilb, and PDonut_AHilb methods were developed and applied on the Irish Nutrient Management Planning Online (NMP Online) agricultural dataset. The polygon-based obfuscation methods introduced in this study were designed with the consideration of properties of spatial polygon objects including the spatial coordinates, shape and size of the polygon, topology, and spatial relationship between adjacent polygons that can be used to identify real-world objects. These methods were developed to guarantee that there is no false-identification and non-unique obfuscation which is important for static polygon objects in terms of accuracy and privacy protection. Qualitative approaches were developed to identify the optimal values of inner and outer radii of donut shape based on k-anonymity satisfaction and subsequently obtain the optimal value of k-anonymity. Several evaluation methods were implemented to compare the methods performance. Density-based methods particularly PDonut-AHilb provide the best trade-off between field parcel confidentiality and spatial pattern preservation and should be considered for researchers and practitioners obfuscating polygon data. 相似文献
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Knowledge based reconstruction of building models from terrestrial laser scanning data 总被引：1，自引：0，他引：1
This paper presents an automatic method for reconstruction of building façade models from terrestrial laser scanning data. Important façade elements such as walls and roofs are distinguished as features. Knowledge about the features’ sizes, positions, orientations, and topology is then introduced to recognize these features in a segmented laser point cloud. An outline polygon of each feature is generated by least squares fitting, convex hull fitting or concave polygon fitting, according to the size of the feature. Knowledge is used again to hypothesise the occluded parts from the directly extracted feature polygons. Finally, a polyhedron building model is combined from extracted feature polygons and hypothesised parts. The reconstruction method is tested with two data sets containing various building shapes. 相似文献
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根据土地利用的时空特点和建立的时空数据模型,运用地理信息技术中的拓扑学关系,将点、线、面这些空间数据与一定的属性数据相连接,处理点线、线线、线面等的空间关系,从而实现对土地变更数据的计算机管理。 相似文献
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针对影像线特征匹配的复杂性,给出了根据物体结构信息,将影像匹配问题转化为确定图同构问题的匹配策略。首先,利用影像特征提取获得的点、线特征建立描述物体结构信息的关系表,通过对左右不同影像的图形进行区域分割获得候选面特征,利用矢量数据拓扑关系的自动建立算法得出左右影像关联图的弧段-多边形拓扑文件。然后,根据基匹配及拓扑关系表,利用图深度遍历的方法进行匹配传递,按面、线、点的顺序完成不同影像间对应物体同名线的匹配。由于关系表的一致性表明了物体构成特征要素的一致性,可使整个影像的匹配搜索范围变小,从而提高影像匹配的准确性与匹配速度。 相似文献
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手机端电子地图处理方法研究 总被引：1，自引：0，他引：1
通过对传统电子地图处理方法的研究与改进，包括删除多余属性、地图裁剪和地图压缩，解决了地图裁剪造成的地理实体重复标识问题，引入“多边形池”技术提高了的Douglas—Peuker算法的运算效率，采用原始数据拓扑检测机制使压缩结果更加精确，采用公共边优先压缩策略解决了多边形边界压缩失真问题。同时吸取了已有的压缩算法改进，包括多边形公共边提取、特征点提取、无损压缩算法等，形成了一整套手机端电子地图处理流程。利用江苏某市数字城管数据对电子地图处理流程进行了实例验证，在项目中取得了较好的效果。 相似文献