Map Legibility Research Articles

Polyline Morphing for Animated Schematic Maps

Thematic maps allow for the visual analysis of spatial data. When comparing two map states, preserving the mental map of a user facilitates the comparison. One way to achieve this is to use animated transitions between the states. This work presents an algorithm for computing such animations, called morphs, between schematized map objects, a technique particularly pertinent in urban mobility scenarios where schematic maps improve map legibility. In schematic maps, abstraction is used to reduce the visual complexity while still conveying information on a selected phenomenon. Our method ensures that the morph has four favorable properties: (1) it is self-intersection-free, (2) it maintains the schematization of the input features, (3) it is self-contained, and (4) every segment moves at its own constant velocity. We present an efficient algorithm to compute vertex traces and the timing of the morph. We evaluate our approach on isochrones visualizing travel times and on different layouts of schematic transit networks. The results show that the additional constraints we induce on the morphing only have a minor influence on the optimization target while they reduce the complexity of the animation.

A Novel Method for Building Displacement Based on Multipopulation Genetic Algorithm

Owing to map scale reduction and other cartographic generalization operations, spatial conflicts may occur between buildings and other features in automatic cartographic generalization. Displacement is an effective map generalization operation to resolve these spatial conflicts to guarantee map clarity and legibility. In this paper, a novel building displacement method based on multipopulation genetic algorithm (BDMPGA) is proposed to resolve spatial conflicts. This approach introduces multiple populations with different control parameters for simultaneous search optimization and adopts an immigration operation to connect different populations to realize coevolution. The optimal individuals of each population are selected and preserved in the elite population through manual selection operation to prevent the optimal individuals from being destroyed and lost in the evolutionary process. Meanwhile, the least preserving generation of the optimal individuals is used as the termination basis. To validate the proposed method, urban building data with a scale of 1:10,000 from Shenzhen, China are used. The experimental results indicate that the method proposed in this paper can effectively resolve spatial conflicts to obtain better results.

Point Label Placement on Hexagonal Map Grids

Abstract. The past few decades have seen the development of automatically feature labelling when manual label placement was thought to be time and labour consuming. Emerging techniques like volunteered geographic information (VGI) collection are making label placement more complexed with many features in a limited space, especially for points of interest (POI). In order to improve the quality and the efficiency of point feature labelling, there have been massive researches focusing on issues like position models, assessment criteria and optimization methods. Most of the researches were using vector-based methods while raster-based methods were less used, because vector-based methods have the advantage of easy definition of features and labels but are usually followed by computation complexity problems for features with high density. In contrast raster-based methods are faster and more flexible, though being harder to represent features and labels precisely on the map grids. Considering that hexagon partitioning was rarely used in raster-based methods, compared with the most commonly used square portioning, and hexagon was potentially useful for its oblique sides and isotropic orientations, hexagonal grids were used in this research to investigate better point feature labelling approaches.A new raster-based method was promoted to figure out high quality label placement of POI in dense area. Labels were placed on a hexagonal map grids based on the principles that one Chinese character is set to one hexagon unit with the mathematical relationship of h = ((√3+1)/2)a, while h is the side length of a hexagon unit and a is the size of a Chinese character. Considering that hexagon grids are divided into flat topped type and pointy topped type, which leads to different orientations, split hexagons were promoted to extend orientations from 6 to 8 based on pointy topped grids. A hexagon is partitioned into two parts labelled ‘left’ and ‘right’ and a split hexagon is the combination of a ‘left’ part and a ‘right’ part separately from two neighboring hexagons, as shown in figure 1. Then every hexagon on the grid will have four status: not-occupied {(0,0)}, half-occupied {(0,1) and (1,0)} and both-occupied {(1,1)}. Based on the fundamental concepts above, specific definitions were made on how labels were supposed to be represented on hexagonal map grids, including the length, orientation, writing direction, character orientation and position of the labels.The approach first initially arranges labels of POI with different combinations of label orientations while pursuing coherence as much as possible, including procedures of rasterization of vector data, POI grouping and initial scheme computation. Every POI in a same group would have same label orientation and every POI group may have several accessible orientations thus making initial schemes diverse. Then a second positioning algorithm was conducted to handle overlapping (labels with POI, labels with labels) problems and improve the overall quality of labelling. The algorithm used the methods of position changing and label turning, which allow label to change its position around POI and sometimes change the orientation when it is necessary to avoid collisions. Quality of labels in a closed block was assessed from three aspects: preferential orientation, occlusion and spaciousness. POI data was chosen from restaurant, hotel and shop facilities and figure 2 showed one of the examples of label placement results using this method. The results have shown good orientation consistency of labels and occlusions were reduced to the lowest, though several label-label occlusions remained due to the limited space. After being compared with vector-based method, the approach has shown better performance on maintaining map legibility, aesthetics and harmony.

The Swiss joint information platform for natural hazards

Abstract. The Swiss Joint Information Platform for Natural Hazards (GIN) has been realized from 2008 to 2010 as part of the Swiss federal government’s OWARNA project, which aimed at optimizing warning and alerting procedures against natural hazard. The first online-version of the platform went productive in 2011 with the primary goal of providing measured and forecast natural hazard data in form of processed cartographic, graphic and other multimedia products to professional users – before, during and after natural hazard events. In Switzerland water-, weather-, snow- and earthquake-related hazards are the most relevant ones.In 2013, an online survey showed that the platform does not fully meet user expectations, particularly as to user experience and usability of its cartographic, web-based user interface. Revaluation and redesign of the overall platform were necessary in order to improve map legibility, caused by the complexity of data, large data amounts, and high spatial density of online, real-time measurement data locations. A new web design and user interaction concept have been developed in 2014 and eventually put online in June 2017. User acceptance testing by means of surveys and direct user feedback sessions were key factors in this perennial redesign process. The GIN platform now features important novel technical and graphical elements: The starting page is based on a dashboard containing virtual dossiers (Fig. 1), with which users configure their desired information, data, and map bundles individually, or use predefined adaptable views on various existing data sets. In addition, there is a new overall spatial search function to query data parameters. A responsive approach further improves the usability of the platform. The focus of these new features is on multi-views involving maps, diagrams, tables, text products, as well as selected geographical areas on maps, and fast data queries (Fig. 2). Current user feedback suggests that the new GIN platform design is well received, and that it is moving closer to its very goal: online monitoring and management of natural hazard events by enhanced usability, more targeted and higher personalization.Several Swiss Cantons (i.e., the political entities in Switzerland below the federation) actively participated, and still participate, in the conceptual GIN platform development process through advisory board meetings and consultations. On the operational level, Cantons actively provide and contribute further natural hazard information and measurement data from their own natural hazard monitoring networks. These additional Cantonal regional-scale data sets help to fill spatial data gaps, where no Federal data is available. GIN thusly integrates natural hazard data from Federal and Cantonal levels (and partly even private level), which adds value to all stakeholders on various political levels involved in natural hazard management (Federal, Cantonal, Regional, Communal crisis committees). Stakeholders not only use GIN’s ample database and cartographic product portfolio to accomplish their early warning and crisis management tasks, but also benefit from seamless, secure and reliable IT-services, provided by the Swiss Federal Government. With the new GIN platform, Switzerland has a powerful, integrative, and comprehensive tool for monitoring and responding to natural hazard events.

Intelligent initial map scale generation based on rough-set rules

A proper initial map scale can help improve map legibility. However, the existing initial scale designs for electronic maps cannot make active adjustments according to the differences in the surrounding geographic information distributions, during map panning or navigation. This causes many redundant zooming operations, which reduce the reading efficiency. To solve this problem, we propose a method based on the rough set, which chooses an initial map scale according to the spatial distribution of the road network. First, the spatial distribution of the road network is evaluated using the neighborhood relation model, with Delaunay triangulations. Next, the data of the road network’s spatial distributions and the corresponding map scale data from user operations are collected at different locations. Then, the relationship rules are extracted based on rough set. Finally, an intelligent initial map scale service is developed according to the rules, and its feasibility and effectiveness are tested using an experimental system. The test results show that the intelligent initial map method can adjust the map scale adaptively and dynamically according to distribution of the road network. Consequently, the map legibility is improved significantly because of the reduction in the number of zooming operations.

DRIVER PREFERENCE CONCERNING IN-CAR ROUTE GUIDANCE AND NAVIGATION SYSTEM MAPS FOR DRIVERS WITH COLOR VISION DEFICIENCY

Abstract: In-car Route Guidance and Navigation Systems (RGNS) are used to help drivers navigate. These maps have mainly been designed to accommodate drivers with normal color vision. However, the color perception of people with normal color vision differs from that of people with color vision deficiency. When navigating, understanding certain kinds of information presented by RGNS maps can be a more complex task for colorblind drivers and traffic safety may be impacted negatively. An important aspect related to the graphic design of RGNS maps is the use of a good combination of colors to improve map legibility. Cartographic representations with good legibility aid drivers in comprehending information and making appropriate decisions during driving tasks. This paper evaluates driver preference for RGNS maps designed for drivers with color vision deficiency. A total of 14 subjects participated in an experiment performed in a parked car. Maps were designed to accommodate red-blinds and green-blinds by using a color simulator and principles of perceptual grouping and figure-ground segregation. Based on the results, we conclude that the map grouping symbols representing car and direction arrows in blue segregated from the route in black was more acceptable to drivers compared to other combinations. It is recommended that RGNS should offer a specific graphic design to support drivers with color vision deficiency in navigating.

Smart Cartographic Functionality for Improving Data Visualization in Map Mashups

Thanks to the growth of geoportal products and online cartographic platforms, access to spatial data has never been so easy for so many people. But access to cartographic knowledge for laypersons using such data is lagging behind. Platforms that allow users to create map mashups from diverse data sources can lead to unsatisfactory cartographic visualization, which reduces the map's legibility and the usefulness of such functions. This article's focus is on creating a framework that supports smart cartographic functions to improve the quality of map mashups. First, we assess the state of cartographic conflicts due to map mashup, using examples from existing geoportals. Afterwards, we describe a framework that allows us to define cartographic functions, focusing on symbology changes and based on a client-side approach. We do not aim to fully model the complex decision-making process of a professional cartographer, but rather to provide a set of smart functions that use appropriate assumptions and constraints based on cartographic principles and semantic information. As proof of concept, the framework and functions are then integrated within a geoportal.

Clutter and Map Legibility in Automated Cartography: A Research Agenda

The clutter effect occurs when there is an excessive amount of information in a map or when this information is disorganized. Measurement of clutter is essential to improve the quality of outputs produced using automated cartographic systems. This paper reviews some existing methods for measuring clutter from different research communities, highlighting the lack of suitable methods for use in automated map design. Three use cases are presented to show what kind of clutter measures are needed to go further with the automation of map design, particularly in generalization, in symbol/style specification, and in heterogeneous data integration and visualization. One measure cannot capture all the aspects of clutter, and combination of clutter measures at each step of the whole map design process should be investigated for automated cartography. A research agenda for clutter assessment regarding some specific cartographic processes is provided.

PREFERENCE FOR MAP SCALE OF IN-CAR ROUTE GUIDANCE AND NAVIGATION SYSTEM

Usability issues of maps presented in-car Route Guidance and Navigation System (RGNS) may result in serious impacts on traffic safety. To obtain effective RGNS, evaluation of 'user satisfaction' with the system has played a prominent role, since designers can quantify drivers' acceptance about presented information. An important variable related to design of RGNS interfaces refers to select appropriate scale for maps, since it interferes on legibility of maps. Map with good legibility may support drivers comprehend information easily and take decisions during driving task quickly. This paper evaluates drivers' preference for scales used in maps of RGNS. A total of 52 subjects participated of an experiment performed in a parked car. Maps were designed at four different scales 1:1,000, 1:3,000, 1:6,000 and 1:10,000 for a route composed of 13 junctions. Map design was based on cartographic communication principles, such as perceptive grouping and figure-ground segregation. Based on studies cases, we conclude intermediate scales (1:6,000 and 1:3,000) were more acceptable among drivers compared to large scales (1:1,000) and small (1:10,000). RGNS should select scales for maps which supports drivers to quickly identify direction of the maneuver and, simultaneously, get information about surroundings of route. More results are presented and implications discussed

An Immune Genetic Algorithm to Buildings Displacement in Cartographic Generalization

AbstractSpatial conflicts may occur when map data are displayed at a scale smaller than that of the source map. This study applies the displacement operator in cartographic generalization to resolve such spatial conflicts and to improve the clarity and legibility of map. The immune genetic algorithm (IGA) is used in this study for buildings displacement to solve conflicts. IGA is based on the genetic algorithm (GA) and employs the self‐adjusting mechanism of antibody concentration to enhance population diversity. Meanwhile, the elitism retention strategy is adopted in IGA to guarantee that the best individual (antibody) is not lost and destroyed in the next generation to strengthen convergence efficiency. The compared experiment between IGA and GA shows that the displacement result produced by IGA performs better than GA. Finally, in order to make the displaced map more attractive to cartographers, two constraints – the building alignment constraint and building tangent relation constraint – are applied in IGA to restrict the buildings’ displacement. The same experimental data are adopted to prove that the improved IGA is useful for maintaining the two constraints.

A vector field model to handle the displacement of multiple conflicts in building generalization

In map generalization, the displacement operation attempts to resolve proximity conflicts to guarantee map legibility. Owing to the limited representation space, conflicts may occur between both the same and different features under different contexts. A successful displacement should settle multiple conflicts, suppress the generation of secondary conflicts after moving some objects, and preserve the distribution patterns. The effect of displacement can be understood as a force that pushes related objects away with properties of propagation and distance decay. This study borrows the idea of vector fields from physics discipline and establishes a vector field model to handle the displacement of multiple conflicts in building generalization. A scalar field is first constructed based on a Delaunay triangulation skeleton to partition the buildings being examined (e.g., a street block). Then, we build a vector field to conduct displacement measurements through the detection of conflicts from multiple sources. The direction and magnitude of the displacement force are computed based on an iso-line model of vector field. The experiment shows that this global method can settle multiple conflicts and preserve the spatial relations and important building patterns.

Dispersion for the point-feature cartographic label placement problem

The point-feature cartographic label placement problem (PFCLP) is a NP-Hard problem arising in design of maps and other graphic objects. For the sake of a better map legibility it is important to avoid overlaps in the process of labeling. This paper examines the PFCLP in the legibility context and proposes a dispersion approach for the problem. It is considered that when all points must to be labeled and overlaps are inevitable, the map can be more readable if overlapping labels are placed more distant from each other. The PFCLP is modeled as a dispersion problem on two mathematical formulations based on binary integer linear programming. Computational tests have provided good results on several generated instances.

Local History Maps in Full Text Resources

In serving patron needs, it is the most detailed maps that pose the greatest challenge to find. Map librarians have strategies for locating detailed maps in their own paper collections and other nearby collections, but are increasingly utilizing major map-intensive Web sites and Web services. Major sites such as the Library of Congress American Memory Project, David Rumsey, Sanborn Fire Insurance Maps and many others bring major map collections to the Internet with interactive functionality appropriate for detailed graphical items. This article is meant to draw attention to an overlooked source of large-scale mapping—book-centered, full-text databases. Six of these resources will be examined for their map content, findability, and legibility.

Multicriteria generalization (MCG): a decision-making framework for formalizing multiscale environmental data reduction

Environmental simulation models need automated geographic data reduction methods to optimize the use of high-resolution data in complex environmental models. Advanced map generalization methods have been developed for multiscale geographic data representation. In the case of map generalization, positional, geometric and topological constraints are focused on to improve map legibility and communication of geographic semantics. In the context of environmental modelling, in addition to the spatial criteria, domain criteria and constraints also need to be considered. Currently, due to the absence of domain-specific generalization methods, modellers resort to ad hoc methods of manual digitization or use cartographic methods available in off-the-shelf software. Such manual methods are not feasible solutions when large data sets are to be processed, thus limiting modellers to the single-scale representations. Automated map generalization methods can rarely be used with confidence because simplified data sets may violate domain semantics and may also result in suboptimal model performance. For best modelling results, it is necessary to prioritize domain criteria and constraints during data generalization. Modellers should also be able to automate the generalization techniques and explore the trade-off between model efficiency and model simulation quality for alternative versions of input geographic data at different geographic scales. Based on our long-term research with experts in the analytic element method of groundwater modelling, we developed the multicriteria generalization (MCG) framework as a constraint-based approach to automated geographic data reduction. The MCG framework is based on the spatial multicriteria decision-making paradigm since multiscale data modelling is too complex to be fully automated and should be driven by modellers at each stage. Apart from a detailed discussion of the theoretical aspects of the MCG framework, we discuss two groundwater data modelling experiments that demonstrate how MCG is not just a framework for automated data reduction, but an approach for systematically exploring model performance at multiple geographic scales. Experimental results clearly indicate the benefits of MCG-based data reduction and encourage us to continue expanding the scope of and implement MCG for multiple application domains.

Evaluation of Analytical Measures of Map Legibility

The generation of maps in real-time web-services introduces challenges concerning map legibility. As these services lack the important input of a traditional cartographer, analytical measures of the legibility are called for. The aim of this study was to develop such legibility measures, and to evaluate them with the help of expert users. Measures of the amount of information, spatial distribution and object complexity were developed and evaluated. The results indicated that some of the measures could be used to describe map legibility.

Tactile Elevation Perception in Blind and Sighted Participants and Its Implications for Tactile Map Creation

Our goal was to determine the optimal elevation of tactile map symbols. Tactile perception research predicts that symbol elevation (vertical height) and texture on tactile maps could influence their readability. However, although research has shown that elevation influences detection and discrimination thresholds for single tactile stimuli and that the physiological response of fingertip receptors varies with texture, little is known about the influence of these parameters on the identification of stimuli in the context of multiple symbols as found on tactile maps. Sighted and visually impaired participants performed tactile symbol identification tasks. In Experiment 1, we measured the effect of elevation on identification accuracy. In Experiment 2, we measured the effect of elevation and symbol texture on identification speed. Symbol elevation influenced both speed and accuracy of identification; thresholds were higher than those found in work on detection and discrimination but lower than on existing tactile maps. Furthermore, as predicted from existing knowledge of tactile perception, rough features were identified more quickly than smooth ones. Finally, visually impaired participants performed better than sighted ones. The symbol elevations necessary for identification (0.040 to 0.080 mm) are considerably lower than would be expected on the basis of existing tactile maps (generally 0.5 mm or higher) and design guidelines (0.4 mm). Tactile map production costs could be reduced and map durability increased by reducing symbol elevation. Furthermore, legibility of maps could be improved by using rough features, which are read more easily, and smaller symbols, which reduce crowding of graphics.

Mapas «usted está aquí»: importancia de la alineación con el ambiente y puntos de correspondencia mapa-medio

This study is concerned with the influence of map/terrain alignment and the number of map/terrain correspondece points on the interpretation of �You-are-here� maps. It was carried out in the Campus of the Universidad de Santiago de Compostela, using a 2 x 2 factorial design. The subjects had to search for a target on the map and move towards it. Four differents map versions were used and, as dependent variables, the following were also used: the map inspection time, the time taken by the subjects to locate the target, the success or failure in the task, several measures of the route, the perceived map legibility, the security and subjective difficulty level of the task. The results showed that the persons spend less time on interpreting and searching for a target on the map when it is aligned within the terrain, and they perceive it more legible than a non aligned one, and select a more adequate route towards the target.

The Solution of Large 0–1 Integer Programming Problems Encountered in Automated Cartography

The placement of text on a map to maximize map legibility, while avoiding graphic overplotting, is a problem in combinatorial optimization. This particular optimization problem can be formulated as a multiple choice integer programming problem, and the integer programming problem has a structure that can be exploited, using a Lagrangian heuristic, to obtain a cost effective solution, even when tens of thousands of variables and thousands of constraints are involved. This paper presents the mathematical formulation of the map label placement problem and describes a computer program implemented to solve it.

The evolution of a graduated symbol software package in a changing graphics environment

Abstract The paper describes the developmental history of a software package for computer-assisted drafting of graduated symbol maps. Given the machinery prevalent 10 years ago, the first version was implemented on a mini-computer with vector-oriented devices, such as mechanical plotters and storage tube terminals. The programs provide functions for plotting graduated symbols of various forms, legends and Line drawing. To improve map legibility the hidden areas in cases of overlapping symbols are removed. The visual separation of the symbols is enhanced by a halo effect, a small gap between the symbols, or the symbols and map background. New hardware required the reprogramming of the package to exploit the extended capabilities of new computers and graphic devices, including colour and hardware area fill. To increase flexibility, portability and maintainability, the graphic standard GKS (Graphical Kernel System) has been used as a device-independent software interface for the third generation of the package.

Some Objective Tests of the Legibility of Relief Maps

The legibility of four different types of relief map (contours, contours with hill shading, layer tints and digital or spot height maps) was compared using 13 different map reading test questions administered to 179 subjects. Many of the questions showed large and statistically significant differences between the four types of map, but no single type of map was best for all purposes. The results demonstrate that the choice of an appropriate relief map has a very real effect on the map reader's performance, and that this choice must depend on the way the map is to be used.