共查询到20条相似文献，搜索用时 31 毫秒
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Categorical Database Generalization 总被引：2，自引：0，他引：2
This paper focuses on the issues of categorical database generalization and emphasizes the roles of supporting data model, integrated datamodel, spatial analysis and semantic analysis in database generalization. The framework contents of categorical database generalization transformation are defined. This paper presents an integrated spatial supporting data structure, a semantic supporting model and similarity model for the categorical database generalization. The concept of transformation unit is proposed in generalization. 相似文献
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GIS应用数据库设计二阶分析模式 总被引：5，自引：0，他引：5
提出了数据库设计二阶分析模式，将二者分别应用于空间数据建模和数据库结构设计中，并以国土资源与房地产管理综合管理系统数据库设计中房地关联部分为例对二阶分析模式的应用进行了说明，对模式的可行性进行了论证。 相似文献
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中国大陆岩石GPS平台Geo TransGIS的设计与实现 总被引：2，自引：0，他引：2
在中国大陆岩石圈地理信息系统研究过程中，提出了一种工具型二维地理信息系统和二三维地理信息系统地功能模块的设计思路，探讨了了面向对象方法，面向对象数据模型，面向对象数据库、无缝集成、开放式数据库互联技术在理信息系统研制中的运用；并用实例证明了此设计方法的可行性和实用性。 相似文献
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工程地质三维空间建模技术及其应用研究 总被引：10，自引：1，他引：10
对工程地质研究的主要三维空间对象(勘探区域三维地质剖面体)进行了规范化的构造描述，对当前主流三维空间建模方法进行了综合分析。在此基础上，结合专业建模对象的构造特点及三维数据模型适用表达对象的不同特性，融合单元分解表示(CE)、构造实体几何(CSG)和边界表示(B-Reps)三种数据模型的建模思想，以及栅格模型的基本体元划分机制和数据组织方式，以不规则五面体为基本分析单元，采用面向对象方法构造模型内各娄对象，提出了一种面向对象的三维矢量与栅格混合模型，实现了勘探区域三维地质剖面体的惟一性拓扑表达，并给出了可视化方案。分析了几例基于此模型的工程地质应用，借以验证该模型在工程地质领域内应用的合理性和可操作性。 相似文献
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《制图学和地理信息科学》2013,40(4):317-331
Automation of map generalization requires facilities to monitor the spatial relationships and interactions among multiple map objects. An experimental map generalization system has been developed which addresses this issue by representing spatial objects within a simplicial data structure (SDS) based on constrained Delaunay triangulation of the source data. Geometric generalization operators that have been implemented include object exaggeration, collapse, amalgamation, boundary reduction and displacement. The generalization operators exploit a set of primitive SDS functions to determine topological and proximal relationships, measure map objects, apply transformations, and detect and resolve spatial conflicts. Proximal search functions are used for efficient analysis of the structure and dimensions of the intervening spaces between map objects. Because geometric generalization takes place within a fully triangulated representation of the map surface, the presence of overlap conflicts, resulting from individual operators, can be detected due to the introduction of singularities in the triangulation, the structure of which is used to generate displacement vectors to resolve the conflict. Examples of the application of the implemented operators are described and illustrated using large scale topographic map data. 相似文献
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面向地质建模的三维体元拓扑数据模型研究 总被引：27，自引：0，他引：27
在对地质对象的基本特征和计算机三维地质建模的基本要求进行讨论的基础上，提出了面向对象的三维体元拓扑数据模型。在该数据模型中，用面向对象的方法将地质对象抽象为点、线、面、体，体类又进一步划分为复合体、复杂体、简单体和体元四类。对所有对象类设计了12种拓扑关系和相应的数据结构。 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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基于语法层的地图综合信息量原则 总被引：2，自引：0，他引：2
地图自动综合的一个首要问题是对地图信息进行数量化,信息量正是对地图表达效率数量化的一种重要手段。本文讨论了地图综合在符号语言学上的层次结构,提出在"典型化"约束下,地图综合应遵循的信息量数量变化规律。该规律为地图自动综合结果的评价提供了数学基础,也能用作基于信息量的渐进式自动综合的评价函数。试验证明,该规律符合地图综合实践的结果。 相似文献
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面向目标的栅格矢量一体化三维数据模型 总被引：1，自引：0，他引：1
首先对现有的三维空间数据模型进行了讨论 ,分析了栅格、矢量和混合数据模型的特点 ,提出了一种面向目标的栅格矢量一体化数据模型。该模型将栅格数据以矢量方式进行组织 ,从而同时具有矢量和栅格数据模型的优点 ,也克服了目前普遍应用的混合模型所存在的缺点。还提出了一种三维空间的三级栅格划分和行次序编码方法。该方法存储空间小 ,便于快速索引和计算。最后 ,给出了具体的数据结构 相似文献
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基于约束条件的地图目标移位 总被引：4，自引：0，他引：4
地图目标移位是地图综合和空间信息可视化研究中的一个重要问题,其难点是如何在移位过程中满足一定的约束条件以保持目标之间的空间关系。本文以城市道路扩张为例,借助带约束性Delaunay三角网,结合有限元和空间推理方法,重点探讨顾及空间关系的基于约束条件的地图目标移位问题,并给出满足一定约束条件下的节点移位算法和计算实例。 相似文献
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分形衰减是指在地图综合中,地图目标随着比例尺的变化其结构形态随之发生改变,其自相似程度是递减变化的,反应到分维数的变化上,称之为分形衰减。本文以分形分析方法作为工具,分维值作为度量参数,分析地图综合中地图目标的分形衰减现象。以扩展分维作为理论基础,从变维分析的角度出发,研究地图目标的自相似程度随比例尺变化而衰减的规律,进一步研究地图目标的尺度指标与分形衰减之间的关系。 相似文献
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Wetland ecosystems have experienced dramatic challenges in the past few decades due to natural and human factors. Wetland maps are essential for the conservation and management of terrestrial ecosystems. This study is to obtain an accurate wetland map using an object-based stacked generalization (Stacking) method on the basis of multi-temporal Sentinel-1 and Sentinel-2 data. Firstly, the Robust Adaptive Spatial Temporal Fusion Model (RASTFM) is used to get time series Sentinel-2 NDVI, from which the vegetation phenology variables are derived by the threshold method. Subsequently, both vertical transmit-vertical receive (VV) and vertical transmit-horizontal receive (VH) polarization backscatters (σ0 VV, σ0 VH) are obtained using the time series Sentinel-1 images. Speckle noise inherent in SAR data, resulting in over-segmentation or under-segmentation, can affect image segmentation and degrade the accuracies of wetland classification. Therefore, we segment Sentinel-2 multispectral images to delineate meaningful objects in this study. Then, in order to reduce data redundancy and computation time, we analyze the optimal feature combination using the Sentinel-2 multispectral images, Sentinel-2 NDVI time series, phenological variables and other vegetation index derived from Sentinel-2 multispectral images, as well as time series Sentinel-1 backscatters at the object level. Finally, the stacked generalization algorithm is utilized to extract the wetland information based on the optimal feature combination in the Dongting Lake wetland. The overall accuracy and Kappa coefficient of the object-based stacked generalization method are 92.46% and 0.92, which are 3.88% and 0.04 higher than that using the pixel-based method. Moreover, the object-based stacked generalization algorithm is superior to single classifiers in classifying vegetation of high heterogeneity areas. 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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Al Tinghua 《地球空间信息科学学报》2013,16(3):56-61
In land-use data generalization, the removal of insignificant parcel with small size is the most frequently used operator. Traditionally for the generalization method, the small parcel is assigned completely to one of its neighbors. This study tries to improve the generalization by separating the insignificant parcel into parts around the weighted skeleton and assigning these parts to different neighbors. The distribution of the weighted skeleton depends on the compatibility between the removed object and its neighbor, which considers not only topological relationship but also distance relationship and semantic similarity. This process is based on the Delaunay triangulation model. This paper gives the detailed geometric algorithms for this operation. 相似文献
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AITinghua 《地球空间信息科学学报》2003,6(3):56-61
In land-use data general-ization, the removal of insignificant parcel with small size is the most fre-quently used operator. Traditionally for the generalization method, the small parcel is assigned completely to one of its neighbors. This study tries to improve the generalization by sepa-rating the insignificant parcel into parts around the weighted skeleton and assigning these parts to different neighbors. The distribution of the weighted skeleton depends on the com-patibility between the removed object and its neighbor, which considers not only topological relationship but also distance relationship and semantic sim-ilarity. This process is based on the Delaunay triangulation model. This paper gives the detailed geometric al-gorithms for this operation. 相似文献