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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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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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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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Dejan Lovrinčević 《The Cartographic journal》2017,54(2):139-146
A good seabed representation is one of the important characteristics of any navigational chart. Along with depth contours and coloured depth areas, soundings are used for this task. All the soundings on a navigational chart are selected for a reason. Soundings contribute to the navigational chart safety aspect by alerting to all the threats and dangers. They also show all the attributes of a seabed relief without overcrowding it, thus maintaining the overall chart quality. Soundings are selected from a hydrographic survey and since it consists of a vast number of data, the process of sounding selection is a challenging and demanding task. It requires experience and knowledge from the nautical cartographer and is mostly done manually. Some types of software nowadays provide an automatic selection feature. This paper analyses a process of automatic sounding selection in the dKart Editor software. On the Croatian side of the Adriatic Sea, ?ibenski Kanal (?ibenik channel) and Kanal Sv. Ante (St. Ante’s channel) are used as the study area. A hydrographic survey of the area represents the input data. The official navigational chart of the surveyed area is used as the basis for determining three different sets of parameters for the selection process. After the selection, obtained results are assessed based on geometrical accuracy and on the conservation level of navigational safety. For geometrical accuracy, the best results were produced by the third set that was divided in two subsets for each channel. It was determined that the nature of the seabed relief had an impact on the selection process. The same set had the best result for navigational safety assessment but it was concluded that all the sets undermined the aspect. Because of these crucial shortcomings noticed in all the tested sets of parameters, the feature is considered inadequate for serious usage as a completely automatic tool for the process of sounding selection on navigational charts. 相似文献
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本文扼要地介绍了80年代中期发展起来并被誉为"数学显微镜"的小波分析的理论、方法、快速算法及其应用,并探讨了小波分析在测绘领域中地图制图方面的应用前景。 相似文献
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建立统一、规范的深度基准体系是海洋测绘成果应用的基本保证。为了消除目前海图应用中水深注记基准面不一致的影响,本文在以往研究成果的基础上,提出了以平均海面基准为中介的海图新旧深度基准的转换体系,并以某实验海区水深数据为例,构建了基于深度基准面更新模型的海图水深注记的更新方法。经试验验证效果良好。 相似文献
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自适应地图可视化系统设计研究 总被引:10,自引:0,他引:10
传统的地图可视化系统设计思想已经不能完全适应现阶段地图可视化系统发展的需要,如何满足不同用户的个性化需求,是地图可视化系统进一步发展所面临的重要问题。自适应地图可视化系统,将自适应理论引入到地图可视化系统的设计开发中,为解决这一问题提供了一种有效的方法。文中阐述了自适应地图可视化系统的概念和提出背景,分析了建立自适应地图可视化系统所需要研究的内容,并以自适应用户界面为重点探讨了设计自适应地图可视化系统的基本原理和方法。 相似文献
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徐肇忠 《武汉大学学报(信息科学版)》1987,(4)
地图物体选取的定额模型和结构模型对机助制图综合和地图数据库专家系统中是缺一不可的。结构模型是在选取定额数量的控制下,解决具体选取那些物体,而研究某物体的选取须考虑的因素甚多,並且其间关系是隐会的,普遍存在模糊性。因而采用传统的二值逻辑来处理会既麻烦又损失较多的制图信息。本文以河流选取为例,用模糊集合理论对其建立结构模型进行初步探讨,并用简单样图说明方法和步骤。 相似文献
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Line generalisation by repeated elimination of points 总被引:1,自引:0,他引:1
《The Cartographic journal》2013,50(1):46-51
AbstractThis paper presents a new approach to line generalisation which uses the concept of 'effective area' for progressive simplification of a line by point elimination. Two coastlines are used to compare the performance of this, with that of the widely used Douglas-Peucker, algorithm. The results from the area-based algorithm compare favourably with manual generalisation of the same lines. It is capable of achieving both imperceptible minimal simplifications and caricatural generalisations. By careful selection of cut-off values, it is possible to use the same algorithm for scale-dependent and scale-independent generalisations. More importantly, it offers scope for modelling cartographic lines as consisting of features within features so that their geometric manipulation may be modified by application- and/or user-defined rules and weights. The paper examines the merits and limitations of the algorithm and the opportunities it offers for further research and progress in the field of line generalisation. 相似文献
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道路选取是根据比例尺的要求,在道路网中保留相对重要道路、舍弃相对次要道路的地图综合操作。从概念层和操作层对两种不同的道路选取策略进行了比较。一种是删除后更新策略,即删除一条道路后更新其他道路的重要度;另一种是删除后不更新策略,即删除一条道路后不更新其他道路的重要度。以常用的stroke重要度排序法为道路选取方法,运用长度、连通度、接近度和中介度的加权来描述道路的重要度,采用相似性、误删率、漏删率等定量指标以及定性的目视判别评价选取结果。以深圳市1∶1万道路网和1∶5万道路网作为研究数据进行了实验。理论上删除后更新策略优于删除后不更新策略,然而实证表明删除后不更新策略在常用定量评价指标上优于删除后更新策略,在定性评价方面则各有优劣。 相似文献
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《The Cartographic journal》2013,50(1):58-66
AbstractA nautical chart is a kind of map used to describe the seafloor morphology and shoreline of adjacent lands. One of its main purposes is to guarantee safety of navigation. As a consequence, the construction of a nautical chart follows very specific rules. The cartographer has to select and highlight undersea features according to their relevance to navigation. In an automated process, the system must be able to identify and classify these features from the terrain model. This paper aims therefore to define ontologies of the submarine relief and nautical chart that will be at the root of a model-oriented generalization process. To the best of our knowledge, no ontology has been defined to formalize the geographical and cartographic objects for nautical chart representation. Thus, a bottom-up approach was developed to extract and model knowledge derived from standards established by the International Hydrographic Organization (IHO) and cartographers’ expertise. The submarine relief ontology formalizes undersea features describing the submarine relief. Four concepts (composition, morphometric class, shape value and depth value) are introduced to describe properties and relationships between undersea features. The cartographic representation ontology of nautical charts will define several concepts (chart, features, isobathymetric lines and soundings) for the representation of undersea features on the chart. 相似文献
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基于禁忌搜索的点状注记研究 总被引:1,自引:1,他引:0
地图注记是为待定位注记求取注记位置的过程,它是自动地图制图中的一个重要的难题,其中点状注记问题可以看作是一个组合优化问题。解决优化组合问题,目前有许多成熟的算法,比如模拟退火法,遗传算法,神经网络优化算法以及禁忌算法等等。目前,模拟退火法,遗传算法和神经网络优化算法已经被用来优化点状注记的配置问题。本文将介绍禁忌算法在点状注记配置中的应用,并用国家1∶250000地形图点状居民地图层数据实验,证明该方法有较高的搜索效率,得到的注记结果基本上解决了压盖问题。 相似文献
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道路路口和拐角是地图制图、地图综合和相关制图规范中经常涉及的一个空间概念,而空间概念的建模、度量和特征识别是地图综合和GIS的难点之一。本文提出了道路路口和拐角的识别与重要性定量度量方法。首先,分析了道路路口和拐角的概念和空间特征,然后,设计了识别算法和步骤,并制定了道路路口重要性的定量度量方法。实验分析表明:本文方法能够正确识别道路路口和拐角,且路口重要性指标能够反映区域地理特点。 相似文献