基于MSORQ-Tree的三维景观地图表示

针对WebGIS多尺寸三维景观地图数据处理问题,提出了一种高速数据索引结构MSORQ-Tree。根据该索引的算法,得出移动WebGIS景观图,将该索引和其他索引进行性能比较。结果显示,基于金字塔分割规则的区域,进行分割四叉树所获取的MSORQ-Tree高速索引可有效处理WebGIS中海量景观地图数据。     

环境空气质量系列专题地图制图方法研究

环境与发展是当今世界共同关注的重大问题。目前我国经济正处于高速发展时期,随着经济社会的快速发展和城镇一体化进程的加快,空气污染问题日趋严重,对人体健康造成很大伤害,因此环境保护的重要性日益突出。本文通过建立环境质量空间数据库,利用地理信息软件ArcGIS为基础平台,将环境空气质量监测数据与地理空间位置进行地理匹配,利用地理信息可视化技术,实现环境空气质量监测数据中各主要空气污染物的浓度时间分布的可视化表达,制作环境空气质量专题地图,有助于有效地从海量监测数据中发现有价值的信息,为环境保护部门提供决策参考依据。     

General Principles for Automated Generation of Schematic Network Maps

Usually, a street map contains various types of detailed information and appears to be crowded. As a result, to many users, a street map looks complicated and is not easy to read and follow. In fact, to a certain degree, too much detail makes the map uninformative and noisy. The London tube map, called a schematic or topological map in some literature, has often been cited as an excellent example of a simplified map. Algorithms have been developed by researchers to automate the generation of schematic maps for road networks. However, it is found that there is still a lack of defined general principles and here four general principles have been formulated for schematisation – the Principle of the Preservation of the Topological Relationship; the Principle of the Preservation of the Main Structure of the Line Network; the Principle of Relativity in Position; and the Principle of Relativity in Length. The first two are the principles of preservation: these two should never be violated. The last two are principles of relativity: it is very desirable to keep these two intact unless there is an absolute need to violate them.     

Influential Visual Design Parameters on TV Weather Maps

Abstract

Information transformation on television weather maps (TVWMs) is influenced by visual elements for a broad range of viewers. This research emphasizes the cartographic aspects of TVWMs through evaluating their visual variables. Currently defined visual variables including basic, dynamic and motion variables are investigated and some suggestions are made to improve their application on TVWMs. The rates of the represented visual information within different frames and the related standard deviation are proposed as measures to improve the performance of the ‘duration’ dynamic variable. The concept of ‘visual expressions’ is introduced, and their applications at the organisational level of map design are discussed. Such expressions (including background, boundary, spatial order, zoom and overview maps) are examined as tools for ‘user orientation’ in particular, and their role as dominant parameters in TVWMs’ cartographic communication is considered. Their incorporation in TVWMs of a number of global news channels is evaluated. Firstly, the concepts of visual design parameters are utilized as a foundation for an analytical evaluation, then an empirical evaluation is carried out based on a statistical investigation of a sample of TV viewers. The resulting ranking order and correlation coefficients for each of the elements shows a firm agreement, corroborating views on the importance and proficiency of the visual elements in communicating weather information. As a result, TVWMs of well-known global TV channels (BBC, Euronews, France24, PressTV) are ranked with respect to the effectiveness of their designs.     

Retrieving Hierarchical Information from Maps: The Role of Metric and Configurational Variables

Abstract

One of the most important challenges for cartographers is to be able to transmit information appearing in maps in a simple manner to users. The commonest strategy to do so consists in displaying visual information in a hierarchical way, that is, making it some elements to appear as being more important than others. Nevertheless, recent research has shown that people also pay attention to configurational information, or information about relationships among elements appearing in a map, to retrieve hierarchical information of it. This is the topic of this paper. It aims to investigate the role of metric and configurational information in enabling people to retrieve hierarchical information from maps. The main problem consisted in identifying ‘the main street’ of different layouts whose paths were sometimes widened to make them appear more important. The main findings show that people retrieved hierarchical information by paying attention to a combination of metric and configurational factors.

One of the main challenges that cartographers face is to transmit information in a way that is simple to understand for everyone. The most frequent strategy for this is to display the information in a hierarchical way; that is, by exaggerating the size or width of specific elements and thus assigning them a greater degree of importance. Nevertheless, recent research has shown that when reading maps, people also read configurational information. This is the topic of this paper. It aims to investigate the role of metric and configurational information in enabling people to retrieve hierarchical information from maps. For this, a set of exercises was designed and carried out where people were asked to identify the main street of different specially designed layouts. The main findings show that people retrieved hierarchical information by paying attention to a combination of metric and configurational factors.     

How to Enhance Cartographic Visualisations of Natural Hazards Assessment Results

Abstract

Cartographic visualisations are important tools for the communication of hazard related data among stakeholders. Although these representations are essential for various hazard management tasks, an analysis of existing hazard visualisations showed that they often disregard cartographic principles. This leads to confusion on the part of users through poor representations and consequently to an impairment of the information flow. The objective of this research is to offer suggestions for enhanced hazard visualisations to facilitate hazard management tasks and decision making. Existing cartographic shortcomings are identified based on an extensive analysis of hazard visualisations and an expert survey. These shortcomings are discussed and improvements for important cartographic elements are presented.     

Investigating the Effectiveness of an Efficient Label Placement Method Using Eye Movement Data

Abstract

This paper focuses on improving the efficiency and effectiveness of dynamic and interactive maps in relation to the user. A label placement method with an improved algorithmic efficiency is presented. Since this algorithm has an influence on the actual placement of the name labels on the map, it is tested if this efficient algorithms also creates more effective maps: how well is the information processed by the user. We tested 30 participants while they were working on a dynamic and interactive map display. Their task was to locate geographical names on each of the presented maps. Their eye movements were registered together with the time at which a given label was found. The gathered data reveal no difference in the user’s response times, neither in the number and the duration of the fixations between both map designs. The results of this study show that the efficiency of label placement algorithms can be improved without disturbing the user’s cognitive map. Consequently, we created a more efficient map without affecting its effectiveness towards the user.     

Reflections on Cartography as the British Cartographic Society Celebrates its Golden Jubilee

Abstract

A questionnaire to 128 drivers included map reading tasks using ½-inch to 1 mile maps produced by Philips (Shell Motoring Maps) and by the Ordnance Survey, followed by questions about which of the two maps was preferred and about the features required in a road map.     

Choosing Geographic Units for Choropleth Rate Maps,with an Emphasis on Public Health Applications

Choropleth maps are the most widely used map type for mapping rates, such as those involving disease, crime, and socioeconomic indicators. The essential step of choosing a geographic unit to map is often made in an ad hoc manner. Among the desirable characteristics of choropleth mapping units are high degree of resolution, homogeneity of population size, homogeneity of land area, observation of minimum population thresholds and land area thresholds, temporal stability and currency, compactness of shape, audience familiarity, data availability, and the functional relevance of the unit to the phenomena mapped. Because of the uneven distribution of human populations, no single geographic unit can meet all of these characteristics in practice, and a well designed choropleth map necessarily involves some compromise. We present guidelines for choosing geographic units that take into account the above criteria, considering 12 geographic units ranging from census blocks to states. Even allowing for differences in scale and purpose, some units confer clear advantages over others.