Computation and visualisation of the accuracy of old maps using differential distortion analysis     

Manuel Claeys Boùùaert  Bernard De Baets  Soetkin Vervust  Tijs Neutens  Philippe De Maeyer  Nico Van de Weghe 《International journal of geographical information science》2016,30(7):1255-1280

The accuracy of old maps can hold interesting historical information, and is therefore studied using distortion analysis methods. These methods start from a set of ground control points that are identified both on the old map and on a modern reference map or globe, and conclude with techniques that compute and visualise distortion. Such techniques have advanced over the years, but leave room for improvement, as the current ones result in approximate values and a coarse spatial resolution. We propose a more elegant and more accurate way to compute distortion of old maps by translating the technique of differential distortion analysis, used in map projection theory, to the setting where an old map and a reference map are directly compared. This enables the application of various useful distortion metrics to the study of old maps, such as the area scale factor, the maximum angular distortion and the Tissot indicatrices. As such a technique is always embedded in a full distortion analysis method we start by putting forward an optimal analysis method for a general-purpose study, which then serves as the foundation for the development of our technique. Thereto, we discuss the structure of distortion analysis methods and the various options available for every step of the process, including the different settings in which the old map can be compared to its modern counterpart, the techniques that can be used to interpolate between both, and the techniques available to compute and visualise the distortion. We conclude by applying our general-purpose method, including the differential distortion analysis technique, to an example map also used in other literature.  相似文献   

中国现代地图学发展的成功经验     

廖克 《测绘科学》2007,32(5):5-8

系统分析和阐明了中国现代地图学发展的成功经验,主要包括:地图事业的发展必须适应国家经济建设和社会发展的需要;重视和积极培养各层次的地图学专业人才;重视地图学的理论研究,不断提高地图编制技术水平,实现由传统工艺向数字化与自动化的根本变革。  相似文献   

线状要素化简算法的分析与评估   总被引：1，自引：0，他引：1  

陈波  朱鲲鹏  薛本新 《测绘科学技术学报》2007,24(2):121-124

线状要素是地图中量最大、形式最多样的要素,它们的化简在自动制图综合中非常重要.目前对线状要素化简的算法研究较多,但其化简质量却少有研究.针对化简算法的基本要求,提出了易于操作的评估化简算法质量的6个方面:面积差、弯曲度、最大拐角比率、化简变化趋势、化简结果一致性和自相交性.通过大量实验,比较了Douglas-Peucker等算法的化简效果,最后对化简中的自相交问题提出了相应的改正措施.  相似文献   

等距离纬度等量纬度和等面积纬度展开式   总被引：1，自引：1，他引：0  

边少锋  纪兵 《测绘学报》2007,36(2):218-223

对数学制图学中经常遇到的等距离纬度、等量纬度和等面积纬度展开式进行新的研究。借助计算机代数系统强大的数学分析功能,给出这些纬度用偏心率幂级数形式表示的正解公式,并且以此为基础,给出纬度用偏心率幂级数形式表示的反解展开式,与以往数值形式表示的反解公式不同,这些反解展开式是以符号形式给出,研究表明计算机代数系统的应用不但极大地提高公式推演的效率和准确度,而且反解系数可以表示为更简单和更便于记忆的符号形式。  相似文献   

采用斜拉式弯曲划分的曲线化简方法   总被引：1，自引：1，他引：0  

钱海忠  武芳  陈波  张景辉  王家耀 《测绘学报》2007,36(4):443-449,456

线要素化简一直是自动制图综合中的重要研究内容。分析已有线化简算法在线弯曲形态保持和单调弧段划分时只考虑一侧等不足,提出线要素的斜拉式弯曲划分和化简新方法。该方法对线要素采用斜剖方式划分弧段,兼顾线要素两侧的弯曲形态;识别出每个划分的单调弧段是U型弧段还是V型弧段,是大弧段还是小弧段,从而分别对其进行不同的处理;在处理过程中,每化简完一个单调弧段,重新对线要素进行弧段划分,然后再次对每个单调弧段进行化简,以此类推,因此该算法是一种动态化简过程。实例显示,本算法在线要素特征点保持、u型弧段和V型弧段保持、大弯曲的保持、整体形态保持等方面非常有效,且化简率非常高,充分证明本算法的科学性和优越性。  相似文献   

A Study of the Local Geometric Accuracy of Count de Ferraris's Carte de cabinet (1770s) Using Differential Distortion Analysis     

Soetkin Vervust  Manuel Claeys Boùùaert  Bernard De Baets  Nico Van de Weghe  Philippe De Maeyer 《The Cartographic journal》2018,55(1):16-35

The eighteenth century Carte de cabinet of count de Ferraris is the first large-scale (1:11?520) topographic map of the entire Belgian territory, making it a valuable source of historical information. In the past, a number of studies have tried to assess the geometric accuracy of this map, but they all suffer from restricted technical capabilities for computing and visualizing the distortions, and most of them only focus on a limited number of the 275 map sheets. This paper therefore seeks to provide the first systematic and in-depth investigation of the map’s local geometric accuracy. Recently, two Belgian government agencies georeferenced the Flemish and Walloon part of the Carte de cabinet with a high level of detail, using some 30,000 ground control points to link the old map to the modern topographic map of Belgium. These data sets represent a new and unprecedented potential source of accuracy information. However, the high number of control points and our desire to compute distortions in an exact, local, quantitative and continuous way meant prominent techniques for studying the geometric accuracy of old maps, such as displacement vectors, distortion grids, triangular nets and the popular MapAnalyst software, were unsuited for this task. To meet all our requirements a new technique called Differential Distortion Analysis, which is influenced by the treatment of distortions in map projection theory, was used instead. Its advantages, structure and application to the Carte de cabinet are discussed in detail. The new technique allows calculating and displaying the map’s local angular and surface distortions with a very high spatial resolution. Consequently, it was possible to identify trends in the obtained levels of accuracy and to relate these to historical facts about the Carte de cabinet’s production process. This has resulted in important new insights into the map’s geometric accuracy.  相似文献   

自发地理信息兴趣点数据在线综合与多尺度可视化方法   总被引：1，自引：1，他引：0  

杨敏  艾廷华  卢威  成晓强  周启 《测绘学报》2015,44(2):228-234

移动及Web环境下,集成各种自发地理信息POI数据与地理框架背景数据的混搭式地图应用,越来越多地出现在主流地理信息平台及LBS服务中。由于缺乏适宜的在线多尺度可视化机制,这种POI数据表达上通常出现拥挤、压盖等冲突现象。针对该问题,本研究将传统的尺度变换方法与在线环境相结合,提出一种面向城市设施POI数据的多尺度可视化策略。即由服务器端通过预处理方式对POI数据进行多层次结构化组织;在此基础上,客户端依据显示比例尺导出对应层次的POI目标,并通过移位操作解决局部存在的符号表达冲突现象。试验表明,该方法符合数字化网络应用的在线实时需求,同时也能获得较高质量的多尺度表达效果。  相似文献   

两种地图点群综合算法的比较     

李赟  闫浩文  刘正军 《测绘工程》2015,(12):43-47

通过搭建实验程序,分别对基于非加权Voronoi图和加权Voronoi图的点群自动综合算法进行验证,详细对比和分析两种算法计算结果对点群的统计信息、拓扑信息、度量信息和专题信息的传递情况,计算部分结果的相似度,从而得出加权Voronoi图点群综合算法更优的结论。  相似文献   

神经网络融合模型在大坝安全监控中的应用     

张帆  胡伍生 《测绘工程》2015,(1):53-56

为了提高大坝安全监控模型的预测精度并检验模型的泛化能力,研究大坝安全监控的统计模型、BP神经网络模型及遗传神经网络模型,并提出基于这两种神经网络的融合模型,结合某拱坝长期的变形观测数据,对上述几种模型进行试算。分析结果表明,所建立的融合模型与其他模型相比具有较高的预测精度,且泛化能力较强,具有良好的适用性。  相似文献   

从眼动实验看地图学实验的哲学意义及作用     

郑束蕾  邓毅博  陈毓芬  李萌 《测绘科学》2015,40(1):28-32

科学活动的哲学三要素包括主体要素、客体要素及工具要素。地图学实验研究作为人类认知世界的科学活动的方式之一,也应该具有以上基本属性。其中,主体要素是制图者和用图者,客体要素是地图,工具要素是各种地图学认知实验方法。文章从哲学角度对地图学实验研究科学活动三要素进行解析,介绍了问卷调查、眼动实验、出声思维等目前常用的各种地图学认知实验方法,并对眼动实验在地图学研究中的作用进行了归纳分析。  相似文献