Searching for Boundaries on Maps: Cognitive Processes

The purpose of this research was to examine the interaction between color and the visual processes people use to search choropleth maps. Two experiments were performed in which subjects searched hypothetical choropleth maps displayed on a cathode-ray tube to determine whether a particular (target) boundary formed by two adjacent polygons filled with different colors was present. In experiment 1, the four pairs of colors used to form the target boundaries were red-blue, green-yellow, green-magenta, and cyan-magenta. In experiment 2, red-green, blue-yellow, red-orange, and cyan-orange were the color pairs used toform the target boundaries. The target boundary colors, target-background discriminability, target boundary location, and the number and types of boundaries on the maps had a significant effect on search time. The results of both experiments indicated that subjects were using a parallel search process followed by a serial search process as described by Cave and Wolfe's (1990) guided search theory. The relative mean search times for the various colored target boundaries was best explained by the opponent process theory.     

World Maps With Natural Boundaries

The graticule of meridians and parallels is a largely artificial type of map boundary that can detract from the display of irregular features such as oceans. Such natural boundaries as shorelines may be used instead as the boundary of world maps. The principle of natural boundaries has been applied to several examples of equal-area or conformal world ocean maps with single or multiple lobes. By careful selection of the poles and centers, these maps can show both oceans and continents in their entirety on a single map.     

A Technique for Building Representation in Oblique View Maps of Modern Urban Areas

Abstract

This paper presents a technique for creating oblique view maps of urban areas. We identify and apply cartographic and cognitive principles to develop a solution in the context of state-of-art geographic information systems. The gap in the ability of these systems to render three-dimensional buildings into maps is addressed. At the core of our solution is a building facade modelling approach that supports varying degrees of abstraction. This is achieved by introducing a concept of 'facade waveforms' and representing building facades as combinations of these waveforms. A Fourier series approximation of the waveforms is used during the rendering processes resulting in an elegant solution to anti-aliasing. The formulation retains the semantic information in the representation that enables meaningful extensions like night time facade generation. The solution is implemented as a pixel shader and therefore leads to a large reduction in texture memory requirement compared with existing building rendering techniques. Additionally, in the case of web based systems, there is significant reduction in bandwidth requirement. We highlight the features of the proposed solution by generating demonstrative maps and images.     

Computer-produced Unclassed Bivariate Choropleth Maps

Many cartographers subscribe to the view that unclassed choropleth maps and multivariate choropleth maps exceed map readers' abilities to process visual information. This paper examines recent evidence which controverts both of these beliefs and discusses applications of a computer program, BICHOR, designed to produce unclassed bivariate choropleth maps interactively on a line plotter or CRT. The maps utilize crossed-line symbolism and putatively overcome both the quantization error inherent in conventionally classed choroplethic displays and the perceptual difficulties associated with color-encoding schemes used for earlier bivariate maps.     

Change Blindness in Animated Choropleth Maps: An Empirical Study

Animated choropleth maps enable cartographers to visualize time-series data in a way that congruently depicts change over time. However, users have difficulty apprehending information encoded within these displays, and often fail to detect important changes between adjacent scenes. Failures of visual experience, such as change blindness, threaten the effectiveness of dynamic geovisual displays, in which several important changes can occur simultaneously throughout the display. Animated choropleth maps require viewers not only to notice changes but also understand symbolic meanings encoded in rapid transitions between scenes. Graphic interpolation between key frames, also known as “in-betweening” or “tweening”, smoothes transitions and lengthens the duration of the transition between scenes in a dynamic sequence. Previous cartographic literature suggests tweening could be a potential solution for change blindness in the cartographic context. This article examines this issue of change blindness in the cartographic context and reports on a human subjects investigation designed to evaluate the influence of cartographic design variables on map readers' change detection abilities. Our results indicate that 1) map readers have difficulty detecting changes in animated choropleth maps, 2) map readers over-estimate their own change detection abilities, and 3) tweening influences the legibility of change in animated choropleth maps.     

Hexagon Mosaic Maps for Display of Univariate and Bivariate Geographical Data

This paper presents concepts that motivate the use of hexagon mosaic maps and hexagon-based ray-glyph maps. The phrase "hexagon mosaic map" refers to maps that use hexagons to tessellate major areas of a map, such as land masses. Hexagon mosaic maps are similar to color-contour (isarithm) maps and show broad regional patterns. The ray glyph, an oriented line segment with a dot at the base, provides a convenient symbol for representing information within a hexagon cell. Ray angle encodes the local estimate for the hexagon. A simple extension adds upper- and lower-confidence bounds as a shaded arc bounded by two rays. Another extension, the bivariate ray glyph, provides a continuous representation for showing the local correlation of two variables. The theme of integrating statistical analysis and cartographic methods appears throughout this paper. Example maps show statistical summaries of acidic deposition data for the eastern United States. These maps provide useful templates for a wide range of statistical summarization and exploration tasks. Correspondingly, the concepts in this paper address the incorporation of statistical information, visual appeal, representational accuracy, and map interpretation.     

Interpolation of Point Values From Isoline Maps

A Bidirectional Hermitian Spline (BHS) method for the estimation of point values from isoline maps is presented and compared to three other methods. Hermitian splines are used and first derivatives are estimated by either Akima's method or by a clamped cubic spline, if Akima's method returns a zero first derivative. Every desired point value is interpolated twice, once by each of two orthogonally-directed splines. The two spline estimates are then averaged using the error formula for Hermitian splines. In addition, a periodic Hermitian spline is constructed around the study-area perimeter (representing a cross-sectional profile of the edge) to damp undesirable edge effects. Point values can be estimated from small-scale isoline maps drawn in spherical coordinates or from large-scale isoline maps drawn in Cartesian coordinates.     

Assessment of Shuttle Radar Topography Mission Elevation Data Based on Topographic Maps in Turkey

Depending on scale, topographic maps depicting the shape of the land surfaces of the Earth are produced from different data sources. National topographic maps at a scale of 1:25 000 (25K maps) produced by General Command of Mapping are used as the base map set in Turkey. This map set, which consists of approximately 5500 sheets, covers the whole country and is produced using photogrammetric methods. Digital Elevation Models (DEMs) created from these maps are also available. Recently, another data source, Synthetic Aperture Radar (SAR) interferometric data, has become more important than those produced by conventional methods. The Shuttle Radar Topography Mission (SRTM) contains elevation data with 3 arc-second resolution and 16 m absolute height error (90 percent confidence level). These data are freely available via the Internet for approximately 80 percent of the Earth's land mass. In this study, SRTM DEM was compared with DEM derived from 25K topographic maps for different parts of Turkey. The study areas, each covering four neighboring 25K maps, and having an area of approximately 600 km², were chosen to represent various terrain characteristics. For the comparison, DEMs created from the 25K maps were obtained and organized as files for each map sheet in vector format, containing the digitized contour lines. From these data, DEMs in the resolution of 3 arc-second were created (25K-DEM), in the same structure as the SRTM DEM, allowing the 25K-DEMs and the SRTM DEM to be compared directly. The results show that the agreement of SRTM DEM to the 25K-DEM is within about 13 m, which is less than the SRTM's targeted error of 16 m. The spatial distribution of the height differences between SRTM-DEM and the 25K-DEM and correlation analysis show that the differences were mainly related to the topography of the test areas. In some areas, local height shifts were determined.     

A Visual Art Interface to an Embedded Sequence of Maps

The role of art in relation to maps is being reappraised on the basis of a perceived ability to depict aspects of a place that maps alone cannot. Many as opposed to one perspective on a place communicates more fully the essence of that place (with art as a valuable source of qualitative geospatial data) and so maps and art should be presented in the same visualization package. This paper outlines the development and implementation of an interface where a scanned painting forms the mode of access to an embedded sequence of maps. The interface is used to represent the history and habitat extent of the kea (alpine parrot) in New Zealand from pre human colonization times through to their present, limited range to a speculation on their future habitat. The painting and the map (in what has been termed in the literature as an anti-map / map combination) are in their own separate layers and joined by an interactive link. The interface harnesses the ability of visual art to aggregate multiple themes, locations and times into a single cohesive image, coupled with map composition and symbology that complements the painting. The ability to contain many temporal instances is close to the comic strip frame (and instances of Renaissance art) in particular, with, in this case, an implicit time frame from left to right on the painting. The use of an artistic image minimizes use of text to depict events, due to the visual and narrative power of the painting.     

IndoorTubes A Novel Design for Indoor Maps

Efforts within cartography on indoor maps have previously not received a lot of attention. Work that has been carried out on indoor maps often focus on map design very similar to an architectural style (Klippel et al. 2006; Ciavarella and Paternò 2004). In some cases the design has been of a more novel character where approaches with augmented and virtual realities have been carried out (Radoczky 2007; Müller et al. 2006). Common to these approaches is the depiction of one floor per map. As well, the primary user task is often solely personal navigation. In this article I present an innovative approach to indoor maps. The design is directly inspired by underground tube maps first developed by Harry Beck (Garland 1994) and today a common design for public transport maps. The main advantages of the map design are its simplicity and the possibility of including all floors in one map view. This allows the map user to easier comprehend the structure of the building without using several maps, as commonly needed with today's indoor map designs. I present several different map styles each intended to satisfy different user groups and tasks depending on the user's familiarity with the environment. In addition the article motivate for new application areas suitable for indoor maps, especially large hospitals. I hypothesize that the design proposed in this article leans very well to displaying real-time dynamic geospatial information, such as patients, staff, equipment and room availability within hospitals. Due to the early phase of the work presented here I outline the needed further work and possibilities of technological platforms as well as evaluations necessary in order for the design to gain acceptance and success.     

Gradation as a Communication Device in Area-Class Maps

This paper proposes a methodology to assess gradation as a cartographic tool for communicating information in area-class maps. The communication model is used as a theoretical foundation, suggesting distinction between errors that occur in encoding and decoding of geographic information. The proposed methodology begins with the determination of a target level of encoding error. Map alternatives are constrained to achieve this target, with gradation considered as one variable in the map production process. The result is a series of maps of equal encoding accuracy but varying in the degree of gradation represented. The individual maps of the series can then be evaluated in terms of decoding accuracy. The methodology is demonstrated by producing a series of alternative forest region maps of New York, Pennsylvania, and New Jersey based on U.S. Forest Service data on tree genus distributions. The series ranges from a 4-class graded area-class map to a 13-class crisp map. The results show gradation to be a viable alternative to the proliferation of map classes as a means of cartographic communication.     

Cartographic Design and Production in the Internet Era: The Example of Tourist Web Maps

Abstract

Some, but not all, branches of the tourist industry make heavy use of maps. The industry has discovered the marketing potential of the Internet but in many cases has not yet fully exploited the extra potential of web maps compared to the traditional paper maps. Web maps can up-to-date tourist information very well but they have to be carefully designed to take account of the limitations of the medium. To be most effective, web maps should be basically simple and convey sufficient information interactively, on request. The map and symbol design should convey intuitively where and how this interaction can take place. This paper summarizes the typical faults found in tourist web map design and provides suggestions on good design practice.     

An Automated Method of Scale Selection and Sheet Configuration for Multiple Sheet Census Maps with Insets

In order to create a useful map, the cartographer must select a scale at which the map reader can distinguish features shown on the map and read their labels. However, the choice of scale for a paper map is also constrained by the size of the map sheet and by the cost of working with a large number of sheets. When the feature density pattern allows, space can be conserved by making the map at more than one scale: a small scale suitable for most of the map, while dense features are shown on inset maps at larger scales. Creating inset maps requires the cartographer to make a series of complex, interrelated decisions regarding the most effective overall sheet configuration, which is dependent upon the scale chosen for the main map and how the inset maps are created. The Census Automated Map Production System (CAMPS) applies cartographic logic and density analysis to make these decisions in a fully automated mapping environment.     

Unclassed Animated Choropleth Maps

Abstract

The potential of unclassed animated choropleth maps as a solution to false patterns of geographic change arising from data classification is investigated. Old concerns about unclassed choropleth maps may be mitigated through map interactivity that offers four advantages over traditional data legends, and previous insights from testing static choropleth maps do not necessarily translate to animated cartography. Data from user testing revealed unclassed animated choropleth maps neither help nor hurt the ability of map readers to understand patterns of geographic change. However, the unclassed map (1) appeared 'less jumpy' to participants and was perceived to run at a slower pace (despite running at the same number of frames per second), and (2) subtle geographic shifts (e.g., seasonal unemployment cycles) were more readily noticed on the unclassed maps. Preliminary results also suggest classed data emphasise stability over time – while their unclassed counterparts improve our ability to see changes. This paper also outlines animated simultaneous contrast as a new perceptual issue in the creation of animated choropleth maps.     

城市拟三维地图生产方法与应用技术研究

通过对传统2.5维地图生产方法进行改进和创新,利用矢量空间分析算法,设计了基于影响范围的渲染索引机制,形成了一套自动化、智能化的地图生产方式,同时突破了传统的2.5维地图的应用瓶颈,为其增加了多角度场景环视和立体空间分析能力,使其生产成果真正迈上了三维应用的台阶,成为了兼具二维和三维地图应用优势的轻量级"拟三维"地图产品。以此方法为基础,搭建了上海市拟三维地图应用系统,为上海公共服务平台的建设和创新发挥了重要作用。     

Knowledge Discovery from Area-Class Resource Maps: Data Preprocessing for Noise Reduction

Spatial data mining techniques have been investigated to extract valuable knowledge from natural resource maps. One challenge in applying general‐purpose data mining algorithms to knowledge discovery from these maps is that the unavoidable existence of errors in traditional area‐class resource maps introduces noise to the process and impacts the accuracy of the extracted knowledge. This paper examines the effect of data preprocessing in knowledge discovery from area‐class resource maps. Presented here is a sampling method designed to obtain samples that exclude noise and are representative of the central concepts of the mapped classes. The method is based on selecting only the pixels that fall in modes of environmental histograms for each individual class. A case study in extracting knowledge from soil maps shows that data preprocessing plays an important role in the knowledge discovery process, and that the sampling method based on environmental histograms significantly improves the knowledge discovery performance.     

The Politics of the Map in the Early Twentieth Century

Drawing on material from several countries, principally Britain, France, and the United States, this paper considers the politics of mapmaking in the years before, during, and immediately after World War I. Following a discussion of some noteworthy but hitherto overlooked mapping projects from the period around 1900, the paper examines the wartime production of maps as aids to geopolitical strategy in three Allied cities—London, Paris, and New York—with particular reference to the major geographical societies in these locations.     

Testing the Usability of Interactive Maps in CommonGIS

The paper reports on an experimental study aimed at assessing the usability of five different interactive tools for exploratory analysis of geographically referenced data implemented in CommonGIS. Usability was assessed in terms of tool learnability, memorability, and user satisfaction. The study provided valuable data concerning the usability of each individual tool; we also derived some conclusions relevant to geovisualization techniques in general. We found that users were, in principle, able to understand and adopt the new ideas of map interactivity and manipulability. However, these ideas needed to be appropriately introduced; people could hardly grasp them just from the appearance of the maps and controls. An introductory demonstration was sufficient to understand the purposes of the interactive tools, and a short training session enabled people to use them. The importance of educating users is a particular challenge for geovisualization tools that are intended to be accessed over the Internet.     

增强现实电子地图应用模式研究

增强现实是真实世界与虚拟信息融合的可视化窗口,增强现实与地图的结合日益受到学者的关注与重视。如何合理地在增强现实界面上表达地图内容,提高用户的认知效率是研究的难点之一。在分析AR与地图结合的特点的基础上,拓展了AR Maps的概念,并重点研究了AR Maps应用场景过程;提出了一种从宏观到微观的地图应用模式;最后设计了基于应用模式的AR Maps地图架构,构建了Android环境下的地图平台,验证了AR Maps应用模式的功能。