FRAMEWORKS FOR GENERALIZATION CONSTRAINTS AND OPERATIONS BASED ON OBJECT-ORIENTED DATA STRUCTURE IN DATABASE GENERALIZATION

1　ＩｎｔｒｏｄｕｃｔｉｏｎＤａｔａｂａｓｅｇｅｎｅｒａｌｉｚａｔｉｏｎｃａｎｂｅｃｏｎｓｉｄｅｒｅｄａｓｔｈｅｔｒａｎｓｆｏｒｍａｔｉｏｎｏｆｔｈｅｃｏｎｔｅｎｔｏｆａｓｐａｔｉａｌｄａｔａｂａｓｅｆｒｏｍｈｉｇｈｒｅｓｏｌｕｔｉｏｎ (ｗｉｔｈｍｏｒｅｄｅｔａｉｌ)ｔｏａｌｏｗｅｒｒｅｓｏｌｕｔｉｏｎ (ｗｉｔｈｌｅｓｓｄｅｔａｉｌ)ｔｅｒｒａｉｎｒｅｐｒｅｓｅｎｔａｔｉｏｎ(Ｍｏｌｅｎａａｒ ,1 996 ) .Ｉｎｏｔｈｅｒｗｏｒｄｓ ,ｔｈｉｓｔｒａｎｓｆｏｒｍａ ｔｉｏｎｉｓｄｅｅｍｅｄａｓｃｈａｎｇｉｎ…     

Feature‐Driven Generalization of Isobaths on Nautical Charts: A Multi‐Agent System Approach

A nautical chart provides a schematic view of the seafloor where isobaths (contour lines joining points of same depth) and depth soundings are generalized to highlight undersea features that form navigational hazards and routes. Considering that the process is ultimately driven by features and their significance to navigation, this article proposes a generalization strategy where isobath generalization is controlled by undersea features directly. The seafloor is not perceived as a continuous depth field but as a set of discrete features composed by groups of isobaths. In this article, generalization constraints and operators are defined at feature level and composed of constraints and operators applying to isobaths. In order to automate the process, a multi‐agent system is designed where features are autonomous agents evaluating their environment in order to trigger operations. Interactions between agents are described and an example on a bathymetric database excerpt illustrates the feasibility of the approach.     

An ontology-driven multi-agent system for nautical chart generalization

ABSTRACT

On 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.     

地图自动综合问题的分解和基本算子集合

从地图综合对象的本质特征出发,结合地图综合的自身规律,分解了地图自动综合问题。同时,在分析已有地图综合算子的基础上,提出了一套具有完备性的地图综合算子集合,讨论了算子的关联性和有序性。     

遥感图像数据库基于内容查询的研究

在分析图像数据库信息特征的基础上，讨论了图像数据库的一般关系模型图像数据库基于内容查询的定义，提出了相应的集合代数模型，指出遥感图像基于内容查询实现的两种方案。并以GIS要素与遥感图像的空间关系为基础，着重分析了GIS支持的遥感图像基于内容查询系统的主要算子，对基于图像特征索引的内容查询，也作了一般形式化的讨论并给出了应用的系统框架。     

自动综合算子分析及算法库的建立

在分析自动综合过程和自动综合系统构成的基础上，指出了自动综合算子库对自动综合的必要性，并以现有的各种综合算子划分为参考，对自动综合算子进行了重新划分，提出了算子库中的算法集合，以此来建立自动综合算子库。     

Map Generalization with a Triangulated Data Structure

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.     

地形图修补测内业整饰常见问题

近年来测绘事业飞速发展,地形图图式已有部分更新。随着数字城市工作的逐步推进,入库工作显得尤其重要。对地形图修补测中旧图式图形改为新图式及其入库方面出现的常见异常问题做一总结,并提出了解决办法。内容主要涉及到图式符号的改变、地形地物属性表的操作、图形实体授权以及其他疑难问题。     

GML空问数据存储映射模型研究

提出了一种将GML文档存储到空间数据库的存储映射模型G2SDB ,同时通过定义边表 ,保留GML文档的部分结构信息 ,有利于处理GML查询中的路径表达式 ,提高查询操作的效率 ,也有利于GML文档的重构。     

基于HBase的空间矢量数据存储模型设计与优化

数据存储模型是数据库模型的重要组成部分。本文针对目前关系型空间数据库发展过程中遇到的瓶颈问题以及采用HBase管理空间矢量数据存在的问题,在分析关系型空间数据库存储模型的基础上,将关系型数据库存储模式向HBase存储模式转换规则应用到空间矢量数据管理领域,提出了空间矢量数据关系存储模式向HBase存储模式转换方法,设计了一种空间矢量数据HBase存储模型。利用HBase的实体嵌套、反范式化、无模式等特性,对模型进行了优化完善。通过试验验证了在没有辅助索引情况下,本文设计的存储模型查询效率优于目前常用的基于HBase的空间矢量数据存储模型。     

Modeling and presenting incomplete and uncertain data on historical settlement units

When entering information about changes of settlements in time into a database, we are dealing with direct facts from historical sources and with interpretations. The source information generally relates to an event or situation at a specific time. This means that we only fill in the parts of the timeline with data objects called (partial) manifestations; however, lack of data does not mean that settlement did not exist. It would take a lot of time to interpret and enter missing information manually. In this article we present a database schema, database procedures and algorithms to generate aggregated settlement unit manifestations in an automated way from their partial manifestations. As a result, it is possible to obtain a continuous history of a given settlement so as to present it on a map.     

矢量地图空间信息度量及其变化分析方法

如何计算地图的空间信息含量是评价制图质量、地图综合算法以及实现空间信息有效传输的重要基础。论文在详细分析现有的空间信息度量方法的基础上,提出了一种空间信息度量的新方法。该方法分别从几何、专题、拓扑以及专题拓扑4个方面来度量地图空间信息。然后,提出利用膨胀和序贯膨胀形态学算子分析几何信息熵、专题信息熵、拓扑信息熵以及专题拓扑信息熵随地图符号影响范嗣不同而引起的变化。通过算例分析发现,利用Voronoi图计算得到的结果是论文方法的一个极值结果（即特例）,并且该方法便于定量分析地图空间信息熵度量随符号影响范围（或大小）的变化情况。     

Road network selection for medium scales using an extended stroke-mesh combination algorithm

The road network is an essential feature class in topographic maps and databases. Road network selection for smaller scales forms a prerequisite for all other generalization operators and is thus a fundamental operation in the overall process of topographic map and database production. The objective of this paper was to develop an algorithm for automated road network selection from a large-scale (1:10,000) to a medium-scale database (1:50,000). The project was pursued in collaboration with swisstopo, the national mapping agency of Switzerland. Three algorithms (a stroke-based, a mesh-based, and a combined stroke-mesh algorithm) were implemented from the literature and analyzed using swisstopo’s large-scale TLM3D spatial database, with requirements set forth by expert cartographers. Initial experiments showed that the combination algorithm performed best, yet still it could not meet all requirements. Therefore, extensions to the basic stroke-mesh algorithm were developed, significantly improving the selection result with real-world, large test databases. Three extensions introduce modifications to the stroke-mesh combination algorithm. Furthermore, two extensions include external feature classes, ensuring accessibility of points of interest and appropriate network density representation in settlement areas, respectively. The results were evaluated by expert cartographers, who concluded that the proposed approach is ready to be deployed in production at swisstopo.     

第三次国土调查的图斑自动综合方法

从第三次国土调查数据库快速缩编派生出多尺度数据库,是地图制图的重要任务。本文针对大量图斑,首先通过研究图斑栅格综合,减少碎图斑数量;然后构建图斑语义邻近度模型、空间几何拓扑模型,分析了顾及拓扑和地区地理特征约束下的地类图斑制图综合方法;最后形成了自动化图斑缩编生产工艺流程。基于上述方法,采用计算机编程技术研发国土三调缩编系统,并应用于四川省某县23万图斑量的三调数据并试验验证。试验结果表明,通过本文方法的成果符合专题制图要求,极大地提高了三调图斑的自动综合效率。     

Categorical Database Generalization

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.     

空间数据库的WFS长事务管理方案研究

在研究网络要素服务WFS-T对长事务管理的需求以及Geoserver等WFS服务器实现技术的基础上,针对目前进程内锁、行锁长事务管理方案未完全保证强事务性和事务持久性的问题,设计了一种包括长事务锁定表、授权校验规则和相应的SQL函数接口的空间数据库长事务管理方案;并在国产地理空间数据库管理系统BeyonDB上进行了验证.     

GENTOOLS在国家1：50000数据库更新工程中的应用研究

1：50000地形数据库更新是一项复杂的地形数据库制作工程。传统的缩编技术工艺与相应的工具难以适应新的生产需要,适应于数字环境下的缩编生产工具的需求则变得非常迫切。GENTOOLS很好地解决了1：50000数据库更新工程中的诸多难题,采用半自动和手动相结合的方法,大大提高了缩编效率,同时也为地形图缩编提供了一种新的选择。     

基于元模式的空间关联规则挖掘方法

空间关联规则可以从空间数据库中发现空间对象之间的隐含的、不明确的空间关系。空间数据库中空间关联规则挖掘研究是空间数据挖掘和知识发现(SDMKD)的主要内容,其主要问题是多层,多关系的规则发现问题。本文把元模式与空间关联规则挖掘相结合介绍了挖掘地理信息系统(GIS)中空间数据库关联规则的常用步骤方法。     

The map of Jerusalem (1538) by Hermanus Borculus and its copies - a carto-genealogical study

A proper characterization of land-use types is critical for constructing generalization constraints to guide and control landuse data generalization. This paper focused on identification and utilization of their importance based upon land-use distributions and application themes. First, this importance was identified using a three-step method that links a diversity index, a multiple attribute decision model and a spatial association analysis. Second, with the importance, a mathematical function was designed to determine minimum area thresholds of land-use polygons as an example of generalization constraints. Third, the importance was used to assist in the selection of generalization operators and evaluation of generalization outcomes. Fourth, a land-use dataset at 1:10 000, describing the land use of a typical rural area in Hubei province of China, was generalized towards a 1:50 000 dataset to verify the effects of the presented method and function. Three additional tests were implemented to analyze the sensitivity of the importance of land-use types on setting the minimum area threshold and generalization operations. The outcome showed that the proposed methods and functions make land-use data generalization more adaptable for in-use datasets and applications.     

Analyzing the effects of scale and land use pattern metrics on land use database generalization indices

The generalization index system is one of the critical issues for computer-aided land use database generalization. This paper studies the scale and land use pattern effects on land use database generalization indices and estimates the thresholds of these indices based on a typical land use database sample. The index system of land use database generalization is discussed and constructed from macro and micro perspectives. Six land use pattern metrics, namely, land use diversity index, land use dominance index, land use homogeneity index, land use fragmentation index, the index of land use type dominance, and the index of land use type fragmentation, are designed to characterize land use patterns and are introduced into the analysis of land use pattern effect on land use database indices. The analysis framework of the scale and land use pattern effects on the land use database indices are proposed by employing statistical techniques. Based on the land use database samples at multiple spatial scales collected in various land use regions across China, the study generates rules for both scale and land use pattern effects on the indices, including map area proportion of land use types, total map load, parcel map load, and minimum parcel area. The thresholds of these indices in land use database generalization are produced at the scales of 1:50,000, 1:100,000, 1:250,000, and 1:500,000. An experimental generalization at county level demonstrates how to determine the generalization index values considering scale and land use pattern, and how to evaluate the generalization results using our macro indices.