共查询到20条相似文献，搜索用时 234 毫秒
1.
WANG Yanbing WU Lixin SHI Wenzhong 《地球空间信息科学学报》2007,10(3):208-212
Constrained Delaunay triangulated irregular network is one kind of dynamic data structures used in geosciences. The research on point and edges insertion in CD-TIN is the basis of its application. Comparing with the algorithms of points and constrained edge insertion, there are very a few researches on constrained edge deletion in CD-TIN. Based on the analysis of the polymorphism of constrained edge, virtual points are used to describe the intersection of constrained edges. A new algorithm is presented, called as influence domain retriangulating for virtual point (IDRVP), to delete constrained edges with virtual points. The algorithm is complete in topology. Finally, the algorithm is tested by some applications cases. 相似文献
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An optimum vehicular path algorithm for traffic network based on hierarchical spatial reasoning 总被引：5，自引：0，他引：5
Human beings' intellection is the characteristic of a distinct hierarchy and can be taken to construct a heuristic in the shortest path algorithms.It is detailed in this paper how to utilize the hierarchical reasoning on the basis of greedy and directional strategy to establish a spatial heuristic,so as to improve running efficiency and suitability of shortest path algorithm for traffic network.The authors divide urban traffic network into three hierarchies and set forward a new node hierarchy division rule to avoid the unreliable solution of shortest path.It is argued that the shortest path,no matter distance shortest or time shortest,is usually not the favorite of drivers in practice.Some factors difficult to expect or quantify influence the drivers' choice greatly.It makes the drivers prefer choosing a less shortest,but more reliable or flexible path to travel on.The presented optimum path algorithm,in addition to the improvement of the running efficiency of shortest path algorithms up to several times,reduces the emergence of those factors,conforms to the intellection characteristic of human beings,and is more easily accepted by drivers.Moreover,it does not require the completeness of networks in the lowest hierarchy and the applicability and fault tolerance of the algorithm have improved.The experiment result shows the advantages of the presented algorithm.The authors argued that the algorithm has great potential application for navigation systems of large-scale traffic networks. 相似文献
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《地图》1989,(2)
The application of Digital Elevation Model (DEM) is drawing more and more attention.Different ways to set up DEM are being tested in line with various local conditions.This paper describes the experiment of setting up DEM on the basis of scanned raster data from separations of contour lines after the pre-processing of the contour image and the running of a program on a microcomputer.The software is designed to simulate the intelligent activities of human experts in evaluating the point elevation for the DEM. 相似文献
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WU HuayiWANG YandongGONG Jianya WU Huayi Associate Professor National Laooratory for momation tngineering in Surveying Mapping Remote Sensing Luoyu Road 《地球空间信息科学学报》1999,2(1):63-67
Polygonal object is a fundamental type of geometric data in vector GIS. The key step of cleaning topological relationship after data collection of polygonal layer is to build polygonal objects from digital arcs. The raw digital arcs may intersect with each other. The algorithm for building polygonal objects after the raw arcs have been split at all intersections is presented. The build-up of polygonal objects in this paper is designed to be implemented by two steps. The first step is to extract all the polygons needed for build-up of polygonal objects from arcs. The second step is to organize polygonal objects from these polygons. For the first step, a tracing algorithm is proposed. The algorithm merely extracts the polygons needed for the build-up of polygonal objects, which is a subset of all the possible polygons that can be induced from the arcs. For the second step, an algorithm based on a specially designed order of polygons is advanced. All the topological relationships among the polygons are sho 相似文献
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An algorithm for automatic cartographic sounding selection 总被引：1，自引：0，他引：1
SUI Haigang CHENG Penggen ZHANG Anming GONG Jianya SUI Haigang Doctoral Candidate National Laboratory for Information Engineering in Surveying Mapping Remote Sensing WTUSM Luoyu Road WUhan China 《地球空间信息科学学报》1999,2(1):96-99
Soundings on nautical charts provide information about the shape of ocean bottom between chart depth curves. A single chart may have thousands of soundings posted on it. This paper describes a new algorithm for selecting soundings automatically. At first,the problem encountered in automatic cartographic sounding selection is presented. Then the authors give the principle of the new algorithm,and the implementation is illuminated in detail. At last the experiments prove the rationality and efficiency of the new algorithm. 相似文献
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空间数据模糊聚类的有效性(英文) 总被引：1，自引：0，他引：1
The validity measurement of fuzzy clustering is a key problem. If clustering is formed, it needs a kind of machine to verify its validity. To make mining more accountable, comprehensible and with a usable spatial pattern, it is necessary to first detect whether the data set has a clustered structure or not before clustering. This paper discusses a detection method for clustered patterns and a fuzzy clustering algorithm, and studies the validity function of the result produced by fuzzy clustering based on two aspects, which reflect the uncertainty of classification during fuzzy partition and spatial location features of spatial data, and proposes a new validity function of fuzzy clustering for spatial data. The experimental result indicates that the new validity function can accurately measure the validity of the results of fuzzy clustering. Especially, for the result of fuzzy clustering of spatial data, it is robust and its classification result is better when compared to other indices. 相似文献
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The problem of taking an unorganized point cloud in 3D space and fitting a polyhedral surface to those points is both important and difficult. Aiming at increasing applications of full three dimensional digital terrain surface modeling, a new algorithm for the automatic generation of three dimensional triangulated irregular network from a point cloud is proposed. Based on the local topological consistency test, a combined algorithm of constrained 3D Delaunay triangulation and region-growing is extended to ensure topologically correct reconstruction. This paper also introduced an efficient neighboring triangle location method by making full use of the surface normal information. Experimental results prove that this algorithm can efficiently obtain the most reasonable reconstructed mesh surface with arbitrary topology, wherein the automatically reconstructed surface has only small topological difference from the true surface. This algorithm has potential applications to virtual environments, computer vision, and so on. 相似文献
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YU Xuexiang associate professor Ph.D Department of Resource Environment Engineering Anhui University of Science Technology Huainan China. XU Shaoquan GAO Wei LU Weicai 《地球空间信息科学学报》2003,6(4):51-56
A new similar singledifference mathematical model ( SS-DM) and its corresponding algorithm are advanced to solve the deformation of monitoring point directly in single epoch. The method for building the SSDM is introduced in detail, and the main error sources affecting the accuracy of deformation measurement are analyzed briefly, and the basic algorithm and steps of solving the deformation are discussed. In order to validate the correctness and the accuracy of the similar single-difference model, the test with five dual frequency receivers is carried out on a slideway which moved in plane in Feb. 2001. In the test, five sessions are observed. The numerical results of test data show that the advanced model is correct. 相似文献
9.
《地图》1993,(3)
Profiles a. The study of land forms from an examina tion of the contour lines is adequate for many pur poses, but when precision is demanded, a profile is usually required. A profile, within the scope and purpose of this manual, is an exaggerated side view of a portion of the earth's surface along a line between two points. 相似文献
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基于等高线膨胀生成规则格网DEM的算法 总被引：1，自引：1，他引：1
介绍一种通过等高线膨胀生成格网的新算法，该算法将等高线栅格化并交替进行4连通和8连通膨胀，两条相邻等高线膨胀的交界处即为相邻等高线的中间等高线，将新产生的等高线通过界线提取加入到栅格等高线中并继续扩张，重复进行直到没有新的中间等高线生成为止。该算法具有易于实现、程序运行速度快、效果较好、生成的差值小和对硬件要求不高等优点。 相似文献
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等高线内插在地图自动综合、地图数字化、三维地形重建等过程中都具有重要意义。许多等高线内插算法在等高线急剧变化以及闭合等高线处存在问题。在分析已有等高线内插算法优缺点的基础上,提出了一种等高线内插算法。该算法以等高线上的节点为圆心,建立与相邻等高线之间的内切圆来探测相邻等高线之间的空间关系,并获取等高线间的辅助线,进而内插出等高线,一方面弥补了已有等高线内插方法中的问题,另一方面有效提高了等高线内插的速度和质量。通过与其他内插算法之间的实验对比分析,验证了本方法的科学性和先进性。 相似文献
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The contour line is one of the basic elements of a topographic map. Existing contour line simplification methods are generally applied to maps without topological errors. However, contour lines acquired from a digital elevation model (DEM) may contain topological errors before simplification. Targeted at contour lines with topological errors, a progressive simplification method based on the two‐level Bellman–Ford algorithm is proposed in this study. Simplified contour lines and elevation error bands were extracted from the DEM. The contour lines of the elevation error bands were initially simplified with the Bellman–Ford (BF) algorithm. The contour lines were then segmented using the vertices of the initial simplification result and connected curves with the same bending direction were merged into a new curve. Subsequently, various directed graphs of the merged curves were constructed and a second simplification was made using the BF algorithm. Finally, the simplification result was selected based on the similarity between several simplification results and adjacent contour lines. The experimental results indicate that the main shapes of the contour groups can be maintained with this method and original topological errors are resolved. 相似文献
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一种从高程格网中提取等高线的算法 总被引：8，自引：2，他引：6
对高程格网内插等高线的算法进行了优化,设计了新的遍历策略,使用两个变量控制内插的方向,在交叉网格处根据新的标准来决定下一步的走向,并且通过新的条件选择遍历开始的单元边,使得算法能够生成满足方向一致化要求的等高线。讨论了降低不规则等高线图形的方法。提出了进一步优化需要考虑的诸多因素。 相似文献
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基于Delaunay三角网的等高线树生成方法 总被引：1，自引：1，他引：0
研究如何利用Delaunay三角网构建等高线树,提出一种新的等高线树生成方法。该方法充分利用Delaunay三角网在领域分析中的优势,通过两次利用Delaunay三角网来判明等高线的空间关系进而达到统一被图廓截断的等高线以生成等高线树的目的。本文将等高线作为约束边构建约束型Delaunay三角网,利用Delaunay三角网查找具有邻接关系的等高线,在此基础上结合邻近等高线的高程关系判明、识别,最终统一被截断的等高线;然后对统一后的等高线再次利用Delaunay三角网查找具有邻接关系的等高线对,利用等高线对的高程关系判断出其为父子关系或兄弟关系,据此将等高线插入到相应的位置,逐步生长成等高线树。同时给出了基于Delaunay三角网的等高线树生成方法的算法设计及试验结果。 相似文献
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DLG内插等高线算法实现 总被引：1，自引：0，他引：1
本文针对DLG(Digital Line Graphic,数字线划地图)编辑过程中出现的等高线残缺,以及手绘实测等高线效率较低等问题,提出了一种用于地图编辑的等高线内插算法。文中介绍了算法的原理、实现,以及在编辑中可能遇到几种情况的处理。算法充分利用了等高线相关知识,速度快、操作简单,内插出的等高线质量较高,且本算法已经用VC++6.0编程实现并作为地图编辑软件DLGMate的一个重要模块,投入实际应用。 相似文献
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等高线高程自动标注算法的研究 总被引：1，自引：0，他引：1
随着数字测图时代的来临,传统纸质图上的等高线逐渐被数字化形式的等高线图(层)所取代,数字等高线的生成与处理已成为了GIS中的一个研究的热点,然而数字等高线高程自动标注算法的人性化仍是一个有待解决的问题。本文依据人们的读图习惯进行了标注的位置和密度研究,提出了一种新的等高线高程自动算法。实验证明,该算法的结果已基本满足人们的读图习惯。 相似文献
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根据等高线数据的特点,提出了一种抗压缩的等高线数据盲水印算法。首先采用逐点前进法对等高线数据进行数据压缩,提取特征点,然后基于量化思想将水印信息嵌入在特征点的小数部分。实验结果表明,该算法具有较好的抗压缩效果。 相似文献