建筑群邻近关系相似性计算

以建筑群的邻近关系为研究对象,在相似性理论的基础上,利用Delaunay三角网和Voronoi图,建立了基于相同特征量的邻近关系相似性模型和基于等距离关系曲线的邻近关系相似性模型,用于邻近关系相似性的定量化计算和判断。     

集成距离变换和区域邻接图生成Delaunay三角网的方法研究

基于距离变换和区域邻接图,提出了一种D-TIN(包括约束的D-TIN)的生成方法。利用D-TIN是Voronoi图的几何对偶这一特性,使用距离变换获取点的Voronoi图,使用区域邻接图获取点在该Voronoi图上的空间邻接关系,以生成D-TIN或者约束的D-TIN。实验表明,与经典的基于数学形态学生成的D-TIN和约束D-TIN的方法相比,本文算法可以分别提高约57.70%和56.64%的效率。     

等高线邻接关系的表达及应用研究

针对当前等高线数据质量控制的问题和不足,提出根据相邻等高线的高程递变规律,利用等高线的邻接关系进行质量检查的设想,进而根据2维平面中Voronoi图的概念,将之应用于等高线数据,提出等高线邻接关系的定义,并设计出等高线邻接关系的基本生成流程,生成等高线的邻接关系表.此外,提出等高线邻接程度的衡量及应用问题,讲述邻接系数的定义、计算及应用.     

A Method for Generating Contour Tree Based on Voronoi Interior Adjacency

IntroductionTopographic contour lines play an i mportantrole in the process of humans analyzing land-form. Particularly ,the spatial relations of con-tours are usually analyzed andinterpreted by hu-mans to recognize topographic features .In orderto model and represent the relationships betweencontour lines ,in 1963 Boyell and Reston pro-posed a contour tree generated by mapping con-tour lines as edges and interstitial spaces asnodes[1 ,2].There has been a great deal of previous workrepresenti…     

地质界线图层的自动化生成方法

地质界线要素是地质图空间数据库的基本要素之一。地质界线图层通常是地质图空间数据库中图元最多的一个图层,其数字化和质量检验工作较为繁重。针对已有地质体面图层,而地质界线图层缺失的情况,本文提供一种快速补充地质界线图层的方法。该方法也可对原生地质界线图层进行属性数据的自动化质量检验。其主要处理环节包括：首先,基于地质体面图层,构建地质体邻接关系图,可实现对地质界线高效、准确地提取;其次,基于产状数据与断层数据,运用地层接触关系识别规则,可分别实现对基本地层接触关系和断层接触关系的自动识别;最后,针对两邻接地质体面实体多段界线间的接触关系识别结果不一致的情形,运用“平行不整合优先”原则和“长度优先”原则,进行了合理的综合判别。基于1:50 000庐山幅地质界线图层的自动化生成实验表明,本文方法可高效、快捷、准确地生成地质界线图层,既能够满足自动化补充地质界线图层的需要,又可作为检验地质界线图层属性的有效工具。     

强度体元基元下的机载LiDAR 3D滤波

针对现有基于二值体元基元的机载LiDAR三维（3 Dimensional, 3D）滤波算法仅利用了数据的高程特征、无法区分相连的地面和非地面目标的问题,提出了一种基于强度体元基元的机载LiDAR 3D滤波算法。首先,基于计算几何理论,将机载LiDAR数据规则化为强度（体元内激光点的量化平均反射强度值）体元结构。然后,基于3D连通区域构建理论,选取局部高程最低的非0值体元为地面种子进而搜寻并标记与地面种子,空间连通、反射强度及坡度值均接近的连通区域内体元为地面体元。算法综合利用LiDAR数据的高程、反射强度及坡度特征,支持相连但强度不同的地面和非地面目标的区分,为相连的地面和非地面目标的精确区分提供更有效的信息。算法有助于提高滤波精度,并扩展基于体元基元的3D滤波算法适用于更复杂的场景。实验基于ISPRS提供的专门用于滤波算法测试的LiDAR点云数据测试了“空间邻域尺度”参数的敏感性及提出算法的精度。定量评价的结果表明：51邻域为最佳邻域尺度;提出算法的平均Kappa系数在相对平坦、陡坡及不连续地形分别为0.9380、0.7749和0.6866;从总误差测度来看,提出算法对比经典的Axelsson算法改进了15个样本中的7个样本精度,且其对比其他二值体元基元下的滤波算法平均总误差最低。     

Supre MapGIS 公交换乘算法设计与实现

公交换乘分析是地图服务的一项重要内容,在对城市公交数据特点进行分析的基础上,提出了一种高效实用的公交换乘算法。该算法通过引入归并站点概念和记录归并站点间步行邻接关系,完善了公交线路和站点之间的关系存储,并有效减少了换乘方案搜索的网络规模。同时,该算法还支持多样化的用户需求：涉及换乘次数、费用、距离、步行距离等方面。最后,本文使用北京市公交换乘数据进行了算法验证和搜索结果分析。     

Spatial relationship-assisted classification from high-resolution remote sensing imagery

Spatial information remains to be an important topic in geographic information system and in remote sensing fields, and spatial relationships have been increasingly incorporated into the image classification processes. Previous studies have employed multiple occurrences of spatial features (shape, texture, etc.,) to improve classification results. However, less attention has been focused on using higher-level spatial relationships for image classification. In this study, two novel spatial relationships, namely, maximum spatial adjacency (MSA) and directional spatial adjacency (DSA), were proposed to assist in image classification. The proposed methods were implemented to extract buildings, beach, and emergent vegetation land-cover classes according to their spatial relationships with their corresponding reference classes. The promising results obtained from this study suggest that the proposed MSA and DSA spatial relationships can be valuable information in defining rule sets for a more reasonable and accurate classification.     

基于WebGIS最优路径分析的设计与实现

综合运用图论概念和面向对象的思想，根据WebGIS中数据模型和数据结构的特点，设计并实现了基于WebGIS的最优路径分析。     

The binational reality of border-crossing cities

In a time of changing border functions city pairs on either side of national state borders have increasingly become objects of attention, because of border crossing contacts and co-operation at the local level. This paper focuses on conceptual aspects of such city pairs, owing their existence to either duplication of an already existing city or to partitioning of a once united city. In search of a proper name that expresses the relations between such partner cities without metaphorical exaggeration, the current vocabulary is reviewed. Especially the notion of the ‘binational city’ receives critical attention. A discussion of selected cases of paired cities in Europe and North-America has been included to underline the importance of local conditions and historical backgrounds with regard to the mutual relations and conditions of co-operation. In conclusion the author states that for the time being ‘border–crossing’ cities seems to be the best name for city pairs of different national backgrounds, the emergence of true ‘binational cities’ being a rather exceptional outcome in a far future. This revised version was published online in July 2006 with corrections to the Cover Date.