地图目标移位的面目标变形约束及其处理

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).     

Continuity markers as an aid for children in finding the peripheral continuity of world maps

ABSTRACT

Many map readers, including both children and adults, find it difficult to determine where they would be located along the edge of a world map after crossing that edge. Different types of markers have long been drawn close to the map’s edge – for example, in an atlas – to help map readers identify the map upon which they will find themselves if that edge is passed. In this study, a method similar to that used to show the continuity between maps in an atlas has been tested to determine whether continuity markers can also be used to help map readers find a world map’s actual peripheral continuity. The study involved children between the ages of 10 and 13 years and showed that continuity markers do help children determine the map’s actual peripheral continuity, in combination with a lesson that describes how to find the actual peripheral continuity of a world map. This article, therefore, concludes that continuity markers for world maps can be a useful part of map design that clarifies how the edges of a world map fit together for children who have learned to use this tool.     

The development and analysis of quasi-linear map projections

Map projections are an essential component of coordinate systems used in applications such as surveying, topographic mapping, and engineering, and care needs to be taken to select ones that minimize distortion for each case. This article explores the selection process for near-linear features on the surface of the Earth and derives limits for the extent of a project that can be projected within specified distortion tolerances. It is then demonstrated that a multifaceted set of projections of the Earth may be used to extend this concept to the mapping of features such as highways and railways that are quasi-linear but do not exactly follow a standard geometrical line (a great circle or a small circle) on the surface of the Earth. A continuous, conformal coordinate system may be derived in such situations, extending to indefinite length and applicable over a swath of several kilometers width, but it cannot be extended to cover situations with extensive variations in height. Instead, the Snake Projection is analyzed, and it is shown that this can be used to develop continuous (non-zonal) projected coordinate systems for major engineering projects extending for hundreds of kilometers and having extensive height ranges. Examples are shown of the application to railway projects.     

地图投影变形球面大圆弧的度量指标

地图投影是地图学的重要研究内容。任何地图投影都不可避免地存在变形问题。针对地图投影的变形,本文提出球面大圆弧和互补比率均值相结合的地图投影面积变形与形状变形指标。通过算例验证和相关性分析,大圆指标一方面简化了小圆指标(即互补比率均值)的计算过程,并能与小圆指标的结果保持一致;另一方面,大圆指标与微分指标之间也具有较高的一致性(形状变形指标的皮尔森积矩相关系数大于0.988)。由于大圆指标不依赖于微分计算,且计算简捷,因此大圆指标更具通用性。本文进一步采用回归分析对大圆指标进行分析,结果表明,大圆指标与微分指标具有较好的线性关系(线性回归的平均误差小于1.10‰)。为了降低采样点数量和解决采样点不统一问题,本文还提出了基于随机采样的指标计算方法,并对随机方法进行了验证和分析。依据大圆指标与微分指标的一致性和线性关系,可以认为使用大圆指标能够有效地评估地图投影的变形情况。     

An iterative approach for inverse transformation of map projections

ABSTRACT

Map projections are given by forward transformation equations. Inverse transformation is derived from forward transformation analytically or numerically. In this paper, a numerical approach for inverse transformation of map projections is proposed, which is based on numerical differentiation and Newton–Raphson root finding method. This approach can facilitate the program developments for map projections when inverse transformation is needed. Numerical differentiation is tested with three map projections. It is seen that seven-digit precision or more can be reached. Boundary conditions and initial guess problem in inverse transformation are discussed. In terms of initial guess, map projections are divided into three categories, and appropriate initial guess values for cylindrical, pseudocylindrical, azimuthal, and conical projections in normal aspect are suggested. Newton–Raphson method with numerical differentiation is tested with 20 different map projections by using test data sets. The results show that the proposed approach is applicable if appropriate initial guess is available.     

地图符号拓扑紧凑性和异质性信息测度

地图拓扑信息的准确测度,对于多比例尺地图表达、制图自动综合等具有重要意义。针对现有地图拓扑信息测度指标多单方面关注地图符号邻接方式的多样性或邻接关系的紧凑性,未能全面刻画地图符号拓扑空间格局与结构特征的问题,提出地图符号拓扑信息的构成包括拓扑结构紧凑性信息和拓扑结构异质性信息两部分。在此基础上,定义了地图符号拓扑结构紧凑性和异质性信息量,提出其计算方法,将其分别用于中国成都市、瑞典耶夫勒市和美国旧金山市的部分路网,结果表明该方法能较为准确地描述路网的拓扑结构。     

Quantitative relations between spatial similarity degree and map scale change of individual linear objects in multi-scale map spaces

Quantitative relations between spatial similarity degree and map scale change in multi-scale map spaces play important roles in map generalization and construction of spatial data infrastructure. Nevertheless, no achievements have been made regarding this issue. To fill the gap, this paper firstly proposes a model for calculating spatial similarity degrees between an individual linear object at one scale and its generalized counterpart at the other scale. Then psychological experiments are designed to validate the new model, taking four different individual linear objects at five different scales as test samples. The experiments have shown that spatial similarity degrees calculated by the new model can be accepted by a majority of the subjects. After this, it constructs a formula that can calculate spatial similarity degree using map scale change (and vice versa) for individual linear objects in multi-scale map spaces by the curve fitting method using the point data from the psychological experiments. Both the formula and the model can calculate quantitative relations between spatial similarity degree and map scale change of individual linear objects in multi-scale map spaces, which facilitates automation of map generalization algorithms for linear features.     

雪龙船南北极考察走航图的制作

“雪龙船南北极考察走航图”是采用新编《系列世界地图》制作的成果。极地考察是一项全球性的重要的科学活动,雪龙船是我国目前唯一的极地科学考察破冰船,表现雪龙船极地科学考察航行路线的走航图,将成为我国南北极考察活动与社会公众沟通的新形式和重要媒介之一。     

An efficient technique for creating a continuum of equal-area map projections

Equivalence (the equal-area property of a map projection) is important to some categories of maps. However, unlike for conformal projections, completely general techniques have not been developed for creating new, computationally reasonable equal-area projections. The literature describes many specific equal-area projections and a few equal-area projections that are more or less configurable, but flexibility is still sparse. This work develops a tractable technique for generating a continuum of equal-area projections between two chosen equal-area projections. The technique gives map projection designers unlimited choice in tailoring the projection to the need. The technique is particularly suited to maps that dynamically adapt optimally to changing scale and region of interest, such as required for online maps.     

儿童电子地图特征及基本设计原则

儿童电子地图是一种儿童电子读物,必须集趣味性与知识性为一体,并充分兼顾儿童的读图和识字能力。本文根据对当前比较有影响的几个地图网站上的电子地图的实际操作并兼顾儿童的生理与心理特征,提出了儿童电子地图的内容设置、特点、功能和设计原则。     

一种新的InSAR相位质量图生成方法

针对传统质量图易受干涉条纹宽度影响,及其在真实相位差等于2kπ的陡峭区域的低识别能力,提出了一种依靠法向量一致性来度量相位质量的方法.在33的缠绕相位窗口中,以中心点为参考点,进行局部相位解缠.解缠后,中心点与每对窗口边界上的相邻点构成8个三角形,将8个三角形的单位法向量合成后的法向量作为局部解缠相位平面的法向量,8个...     

地形图图廓整饰的设计与实现

图廓整饰是地形图的重要组成部分,也是地图输出过程中的一个重要环节。针对现有软件生成图廓整饰缺乏标准性和灵活性的问题,文中分析不同比例尺地形图图式规范,归纳总结出图廓整饰的内容,并根据图形特征与位置分布加以分类。在此基础上提出一种设计方案,通过对每个整饰要素定义相对坐标系和添加参数属性的方法,可以实现整饰要素的精确生成以及灵活调整。根据设计方案进行相关开发予以实现,实践结果表明,该方案确实有效,能实现地形图图廓整饰的自动化生成,提高制图工作效率。     

地形图的确定性与不确定性

地形图是地球科学研究中的基础资料。本文阐述了地形图上等高线、线性要素、面积要素的确定性与不确定性,即除非比例尺为1∶1,否则等高线并不真正具有“等高线上点的高度相等”的意义,这一不确定性特征,这种不确定性随着比例尺、地貌类型等的变化而变化。线性要素、面积要素的确定性与不确定性问题与之类似。     

1∶10000及1∶50000比例尺DEM信息容量的比较——以陕北韭园沟流域为例

运用比较分析与数理统计的方法,以1:10000DEM为基准,探讨在黄土丘陵沟壑区1:50000地形图所建立的数字高程模型描述地表形态的精度特征。样区为陕北绥德县韭园沟流域,基本技术平台为ARC/VIEW地理信息系统软件,研究结果表明,在该地区内,利用1:50000DEM所提取的降水累积量、地面坡度、地面坡向3种地形因子都不同程度地存在着误差。该研究成果对于DEM应用精度的估算与误差的纠正,都有一定的指导意义。     

地图目标移位的面目标变形约束及其处理

在分析地图目标移位及面目标变形一般约束条件的基础上,利用骨架线划分面目标的空间结构层次,并通过制定相关的参数赋值策略,应用有限元方法求解移位过程中的面目标变形。     

序列比例尺地图缩编中建筑物综合算法

针对在序列比例尺地图综合中较少涉及如何构建面向大规模工程化应用的、顾及不同居民地分布特征的建筑物综合算子的现状,该文以广州地区为例,从纵横两条线开展。纵向上,对建筑物随尺度变换依次从单幢房屋向建筑群组、建筑区域、街区转换过程中涉及的综合操作和关键算子进行研究;横向上,主要研究同一尺度转换过程中顾及空间分布特征的建筑物多边形分组合并方法,基于"分而治之"的思想对城区、城中村、郊区等三种典型样本设计综合算子。该文设计的算子兼顾了适用性和效率,在广州地区序列比例尺空间数据库快速构建中得到了应用。     

一种新的地图数据检索方法及其应用软件

本文提出了一种新的实用地图数据检索方法——“放大镜”式地图数据检索,建立了相应的软件系统,并讨论了该方法的数学基础、软件的特点,还给出了应用实例。     

土地利用现状图扫描符号的自动提取与识别

土地利用现状图扫描符号的自动提取能节省人力财力物力。本文采用地图代数和人工神经网络的方法进行扫描现状图符号的自动提取和识别。首先根据图例建立用于特征匹配的符号模板库,然后使用加壳变换和蜕皮变换进行点状符号和线状符号的分离,并使用Canny算子平滑符号,再通过人工神经网络的训练进行色彩聚类而实现符号分割。定义多重相似度,实现符号的预分类识别,在此基础上计算加权距离再次识别。最后采用加壳变换连接断点并提取骨架线对这些断线进行连接,形成完整的线状符号。实验表明,本方法的正确率达到90%以上。     

车载移动测量系统在大比例尺地形图数学精度检测中的应用

研究了车载移动测量系统在大比例尺地形图数学精度检测中的应用。首先在小范围内对其进行了相关试验,得到其有效性后,对某市全市域的地形图进行了抽样检测;对车载移动测量检验与常规方法检验在外业数据采集、内业数据处理及存储量等几方面进行了比较,分析了车载移动测量检验方法的优劣性,为提高测绘质检效率提供了一种新方案。     

互联网地图搜索引擎视觉质量的模糊评价与可视化分析

本文采用用户分类调查和模糊评价方法,对互联网地图搜索引擎案例的视觉质量现状进行综合评估和横向比较,并对评语细化差异进行分类分用户的多变量可视化分析.总体评价结果为"良",国外比国内略好.其中,各指标权重表明,颜色配置、界面构图和道路表达对互联网地图的视觉效果起首要的决定作用.最后,基于用户为中心和跨学科协同的理念,提出...