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Über dieses Buch

This book presents a selection of manuscripts submitted to the 2017 International Cartographic Conference held in Washington, DC at the beginning of July and made available at the conference. These manuscripts have been selected by the Scientific Program Committee and represent the wide-range of research that is done in the discipline. It also forms an important international collection representing research from at least 30-40 countries.



The Span of Cartography


Cartographic Memory Preservation of the Petrópolis City in Brazil: Koeler Map Scanning Using Photographic Survey

Historical cartographic documents have been increasingly essential to several studies, especially when understanding how the current forms of a landscape are structured. In this regard, these documents, along with the assistance of new digital technologies, are preserved and made available to the public. This research focused on investigating the Koeler Plan, a document providing guidance on urban planningUrban planning for the development of the city of Petrópolis. The plan’s milestone is the Petrópolis Map (1846), which became known as Koeler MapKoeler Map, in honor of its creator. The map was made at a scale of 1:5,000 and contains different cartographic elements such as hydrography, public parks, streets, blocks, and land reserved for public and religious buildings. This research aims to digitally reproduce this map, since its restoration and further use are quite difficult due to its current conditions. The methodology comprises photographic survey techniques using a high resolution digital camera and a track system which moves the camera vertically and horizontally. Several tests were made using multiple georeferencingGeoreferencing algorithms to check which of them would better adjust into a mosaic the 191 photographs taken and preserve the features for the digital map generation. The process was developed in five pairs of photographs distributed along the map area, using ArcGISArcGIS 10.1 software with different transformations: Zero Order Polynomial, 1st Order Polynomial (Affine), 2nd Order Polynomial, 3rd Order Polynomial, Adjust, Projective Transformation, and Spline. After georeferencing these pairs, a test was made based on the distortions produced in area and length, in addition to the RMS for each transformation. From these results, it was found that the 1st Order Polynomial (Affine) transformation had lower distortion values for the photographs, Preservation of archiveswhich allowed a highest quality photo mosaicking.

Manoel do C. Fernandes, Tainá Laeta, Deivison F. dos Santos, Paulo M. L. de Menezes

Location Spoofing in a Location-Based Game: A Case Study of Pokémon Go

The worldwide Pokémon Go Pokémon Gofever has brought location spoofing Location spoofinginto the public’s spotlight. Location spoofing is an intentional act to masquerade locational information to somewhere other than the actual location where a network communication takes place. In the realm of Cartography and GIScience, compared with well-studied spatial quality issues, our knowledge of location spoofing is still quite limited. By reviewing five frequently-conducted location spoofing techniques for Pokémon Go, this paper critically examines location spoofing as an emerging spatial data qualityData quality issue. To unveil the hidden motivation for location spoofing, we discuss the uneven spatial distribution of game rewards through mapping a large volunteered data set of worldwide Pokémons, and gaze at the major actors in the location-based game, including location spoofers, game designers, hackers and bots. Though the research scope of this paper lies in a location-based game per se, location spoofing widely exists in Internet applications and is not fundamentally different from other deceptive phenomena in the real world. We encourage cartographers and GIScientists to face this spoofing phenomena head-on in order to promote more effective and trustworthy uses of geospatial big data.

Bo Zhao, Qinying Chen

Crowdsourcing and Data


Educational Aspects of Crowdsourced Noise Mapping

Examined here is a project-based method for integrating of crowdsourced noise mapping Noise mappingin the teaching of geoinformatics. Practical examples of a GISGIS course are designed to use crowdsourced noise measurements in the curricula. The approach showed students how GIS integrates data acquisition, processing, analyses and visualization. Implementing noise measurement tasks in the curricula also helped students gain skills in detecting and resolving errors. The teacher acts as a mentor during the classes in order to help students acquire knowledge in a way that best suits them. A project like this is helpful because it makes the problem easily understandable and offers several cartographic visualization methods that the students can test and compare in practice. In addition, we found that the quality and the accuracy of students’ performance improved during the semester. The students share their knowledge and their experiences. They also learn to cooperate because the success of their project is dependent on the collective work of each student. The most recent methods are presented to the students during the whole working process and lets them discover good and bad solutions.

Andrea Pődör, László Zentai

Crowd and Community Sourced Data Quality Assessment

Data quality IGNassessment Quality assessmentof different volunteered initiatives and platforms presents several challenges for data validation given the high amount of data collected. This paper focuses on two goals. The first consists in defining both a generic workflow and data quality Data qualityindicators for validation of reports coming from crowd and community sourcing platforms. In the proposed workflow, a qualified report can be even described by each indicator separately or by a combination of them. Here, we focus mostly on analyzing the results obtained for each indicator separately. The second goal is to learn more information about contributors who has engaged in a platform proposed by a public body (i.e., the French National Mapping Agency): Who are they? How are they contributing? What are their motivations? More is known about contributors to OpenStreetMap OpenStreetMap (OSM)than of any other VGIVolunteered Geographic Information (VGI) platform. Indeed, knowing the contributors is a crucial task for both motivation and data qualityData quality, especially now that public institutions are engaging with VGI.

Laurence Jolivet, Ana-Maria Olteanu-Raimond

Crowdsourcing Mapping and Participatory Planning Support System: Case Study of Brno, Czechia

Many cities have started to engage their citizens in collaborative planning and in re-creating the urban spaces where they live. The case study presented in this paper crowdsourced subjective/emotional responses concerning the environment of the city of Brno in the Czech Republic, from 2,087 respondents, who marked 24,065 points on six different topics and added over 3,000 further comments. The paper presents not only the case study, but also the authors’ own web-application called Emotional Maps—built for crowdsourcing Crowdsourcingspatial data, mainly about city development and subjective perceptions of urban spaces. The collected data showed three main hot-spots in the city, with a significant number of marked points reported by citizens. The paper comments on the reasons these spots are important for the citizens of Brno and their suggestions for future activities there. Furthermore, the authors argue that ad hoc flexible web-mappingWeb-mapping platforms such as the one presented in the paper can be an asset to city administrations as well as urban planners.

Jiří Pánek, Vít Pászto

A Framework for Enhancing Real-Time Social Media Data to Improve the Disaster Management Process

Social MediaSocial media datasets are playing a vital role providing information that can support decision-making in nearly all domains. This is due to the fact that social media is a quick and economical approach for collecting data. It has already been proved that in case of disaster (natural or man-made) the information extracted from Social Media sites is very critical to Disaster ManagementDisaster management Systems for response and reconstruction. This study comprises of two parts: The first proposes a framework that provides updated and filtered real time input data for the disaster management system through social media, and the second consists of a designed web user API APIfor a structured and defined real time data input process. The aim of this study is to propose a framework that can filter and organize data from the unstructured social media sources through recognized methods and bring this retrieved data to the same level as that acquired through structured and predefined mechanisms, such as a web API. Both components are designed such that they can potentially collaborate and produce updated information for a disaster management system to carry out accurate and effective decision-making.

Syed Attique Shah, Dursun Zafer Şeker, Hande Demirel

Building a Real-Time Geo-Targeted Event Observation (Geo) Viewer for Disaster Management and Situation Awareness

Situation awareness plays an important role in disaster response and emergency management. Displaying real-time location-based social media messages along with videos, pictures, and hashtags during a disaster event could help first responders improve their situation awarenessSituation awareness. A geo-targeted event observation (Geo) Viewer was developed for monitoring real-time social mediaSocial media messages in target areas with four major functions: (1) real-time display of geo-tagged tweets Tweetswithin the target area; (2) interactive mapping functions; (3) spatial, text, and temporal search functions using keywords, spatial boundaries, or dates; and (4) manual labeling and text-tagging of messages. Different from traditional web GIS maps, the user interface design of GeoViewerGeoViewer provides the interactive display of multimedia content and maps. The front-end user interface to visualize and query tweets is built with open source Open sourceprogramming libraries using server-side MongoDB. GeoViewer is built for assisting emergency responses and disaster management tasks by tracking disaster event impacts, recovery activities, and residents’ needs in the target region.

Ming-Hsiang Tsou, Chin-Te Jung, Christopher Allen, Jiue-An Yang, Su Yeon Han, Brian H. Spitzberg, Jessica Dozier

The Academic SDI—Towards Understanding Spatial Data Infrastructures for Research and Education

The demand for geospatial data across different disciplines and organisations has led to the development and implementation of Spatial data infrastructurespatial data infrastructures (SDI)SDI and the theory and concepts behind them. An SDI is an evolving concept about facilitating and coordinating the exchange of geospatial data and services between stakeholders from different levels in the spatial data community. Universities and other research organisations typically have well-established libraries and digital catalogues for scientific literature, but catalogues for geospatial data are rare. Geospatial data is widely used in research, but geospatial data produced by researchers is seldom available, accessible and usable, e.g., for purposes of teaching or further research after completion of the project. This chapter describes the experiences of a number of SDI implementations at universities and research institutes. Based on this, the Academic SDI, an SDI for research and education, is defined and its stakeholders are described. The purpose, scope and stakeholders of the Academic SDI Academic SDIare described based on the formal model of an SDI developed by the International Cartographic Association (ICA) Commission on SDIs and Standards (formerly the Commission on GeoinformationGeoinformation Infrastructures and Standards). The results contribute to understanding the state-of-the-art in SDI implementations at universities and research institutes; how the Academic SDI differs from a ‘regular’ SDI; and which role players need to be involved in a successful SDI implementation for research and education.

Serena Coetzee, Stefan Steiniger, Barend Köbben, Adam Iwaniak, Iwona Kaczmarek, Petr Rapant, Antony Cooper, Franz-Josef Behr, Govert Schoof, Samy Katumba, Rumiana Vatseva, Kisco Sinvula, Harold Moellering

Map Design


Introducing Leader Lines into Scale-Aware Consistent Labeling

Consistently placing annotation labels across map scales often poses a problem due to the restriction of the screen space. This problem becomes further exacerbated when we navigate by arbitrarily zooming in and out of digital maps on mobile devices. In this paper, we introduce leader lines Leader linesto conventional techniques for scale-aware consistent labeling to accommodate more annotation labels on the map domain while retaining their plausible arrangement. The overall visibility of annotation labels is optimized using genetic algorithms while avoiding their unwanted popping effects and sudden leaps regardless of the change in the map scale. The feasibility of the proposed approach is demonstrated by experimental results including comparison with relevant techniques.

Hsiang-Yun Wu, Shigeo Takahashi, Sheung-Hung Poon, Masatoshi Arikawa

On the Way to Create Individualized Cartographic Images for Online Maps Using Free and Open Source Tools

The goal of the research was to create online maps with dynamically changing cartographic images according to the users’ map reading skills, by only using open source tools and resources. The maps were designed for three map reader groups (beginners, intermediates and experts). We used OpenStreetMap OpenStreetMap (OSM) and Shuttle Radar Topography Mission (SRTM)SRTM data to create the maps in QGISQGIS. To display the maps online, we used QGIS ServerQGIS server on the server side, and OpenLayersOpenLayers on the client side. Based on earlier studies on map reading skills and cognitive load, the map design and generalization aimed to maximize the map reading efficiencyEfficiency of the target group. In the grouping process, an online test was used to measure the map reading competences of the map readers, such as the interpretation of hypsography, orientation skills, distance and travel time estimation, interpretation of map symbols, interpretation of geographic names and interpretation of topographic objects. The design and generalization of the map features were based on the map data categories (such as hypsography, coverage, roads, etc.) and they are different on the three maps.

Csaba Szigeti, Gáspár Albert, Virág Ilyés, Dávid Kis, Dávid Várkonyi

Hebrus Valles—The Mars Exploration Zone Map

Hebrus VallesHebrus Valles is one of the 47 candidate Exploration Zones for the first human landing mission of NASA on Mars. The area meets specified criteria for a scientific expedition—among others, it has potential for the water and other resources necessary to perform such a mission. The aim of the project described in this paper was to attempt to create a specialized map for Mars explorers working in the field. The map of Hebrus Valles proposes locations for the landing zone, habitation zone, regions of interests, and traverses. The proposed map also contains descriptions of the geomorphological features of the landscape and warnings about surface hazards. When combined, these elements produce a surface operation map with special requirements that are unlike any map produced on Earth, perhaps the closest analog is hiking maps. This paper presents a detailed characterization of the map, as well as projecting methodology. The process of panchromatic sharpening is the most important part of mapping, mainly due to the effective fusion between a high resolution digital elevation model and a low-resolution color image. A description of tasks carried out using the cartographic tools JMARSJMARS, ArcMapArcMap and PhotoshopPhotoshop is also included. In conclusion, this paper introduces possibilities of implementation of an interactive variant of the map and provides ideas that may be applicable for designing a cartographic system for future operations on the surface of another planet.

Mateusz Pitura

XY Domain: A Sound Map Artwork for Communicating Big Data Characteristics

This paper details a sound mapSound map artwork with a visual mapVisual map component in order to communicate the characteristics of Big Data, namely the volume, velocity, variety and uncertainty aspects of such datasets. It represents an attempt to address a part of the current research agenda on applying cartography to the visual representation and interaction with big spatial datasets. As an artist-scientist collaboration, the research concentrates on electrical signals and humans as transducers of those signals into data. We trace the evolution of the artwork, details construction, collection of representative signal data and context, leading to its exhibition as part of an “Art and Space” theme in a gallery in Dunedin, NZ. Finally, an explanation of and reaction to, the artwork is provided. Visitors reacted positively to the artwork, which conveyed the characteristics of Big Data Big datathrough a mix of tactile Tactileand embodied interaction, sound representations and visual cartographic design/spatial data choice elements.

Antoni B. Moore, Charlotte Parallel

Reproducible Cartography

This paper deals with the production of statistical mapsStatistical maps as part of the wider reproducible research paradigm. The current and most widespread ways to produce statistical maps combine several software products in a complex toolchain that use a range of data and file formats. This software and diversity of formats makes it difficult to reproduce the same analysis and maps. The aim of this paper is to put forward a unified workflow that allows map production in a reproducible process. We suggest hereby the cartography packageCartography package, an extension of the R softwareR software, that fills the need of specific thematic mapping solutions.

Timothée Giraud, Nicolas Lambert

Evaluating Map Quality


Effectiveness and Efficiency of Using Different Types of Rectangular Treemap as Diagrams in Cartography

TreemapsTreemap has been used as diagrams in cartography to visualize hierarchical, multivariate, and time series data through the construction of hierarchies. Several algorithms exist for generating Treemaps. Despite the popularity of the Treemap, few studies have analyzed the effectiveness and efficiency of different algorithms. A user studyUser study was conducted to evaluate the slice-and-dice, squarified, ordered, strip, and ordered squarified algorithms. In the user study, the accuracy and response time for completing tasks were recorded. The slice-and-dice algorithm was identified as most suitable to represent true hierarchy (intrinsic hierarchy), followed by pivot-by-size. Slice-and-dice was also identified as the most suitable algorithm for representing false hierarchy (imposed hierarchy). When representing time series, slice-and-dice, strip, and ordered squarified algorithms were all determined to be suitable.

Mengjie Zhou, Yan Cheng, Ning Ye, Jing Tian

The Usability of a GeoVisual Analytics Environment for the Exploration and Analysis of Different Datasets

A GeoVisual Analytics (GVA)GeoVisual Analytics (GVA) environment is based on highly interactive and dynamic visualization techniques intending to reveal knowledge in complex and multivariate datasets. By depicting information, these techniques amplify human capabilities and facilitate the performance of cognitive tasks for pattern recognition, decision-making or analytical reasoning. However, the question is whether those visual representations are suitable for visualization of different types of data to perform similar tasks. The limited usability Usabilitystudies that have been done on interactive analytical environments have failed to yield a definite answer. Therefore, this paper presents an evaluation experiment on how an interactive GVA environment can be designed that will effectively support similar task execution processes for different use cases. In the GVA environment investigated, four graphic representations of the Space-Time Cube (STC)Space-Time Cube (STC), graphs and maps are interactively integrated to allow data manipulation from location, attribute and time perspectives for overview and detailed analysis. The results of the experiment revealed that the four visual representations in a GVA environment appear to be effective and efficient to explore different datasets with similar tasks, but require some sophistication.

Irma Kveladze, Menno-Jan Kraak, Corné P. J. M. van Elzakker

Characterizing Maps from Visual Properties

Customized mapping needs to rely on a strategy to help mapmakers in designing their maps. Our approach is based on analogy between existing sample maps and the wished customized map. The challenge consists in being able to offer the appropriate maps according to each mapmaker’s specifications. We have focused on the perception of seven selected visual properties of maps. To qualify this perception, a user test User test was set up. A sample map database was built in order to collect assessment of participants about visual properties. Test results were investigated through property and by statistical features. Analyses show that among properties, some are scored as more extreme and/or unanimous than others. Correlations between properties were also highlighted, which clarifies the characterization of sample maps. We then suggested a way to discover the database in a custom-made mapCustom-made map process by using relevant queries based on statistical features of properties. Recommendations on exploiting a sample map database are finally formulated.

Catherine Dominguès, Laurence Jolivet

How Hard Is It to Design Maps for Beginners, Intermediates and Experts?

An online map reading test was done with 859 subjects to statistically measure the efficiency Efficiencyof information retrieval from three different cartographic images of the same area. The differences between the maps were defined by the graphic variables of size, color, pattern, etc., for six map data categories: linear features, hydrography, land cover, elevations, point-like objects, geographic names. The subjects solved map reading tasks related to these categories. Cartographic images were designed for each of the three map reader groups: beginners, intermediates and experts. The design method and the grouping were based on the results of previous studies, and the grouping was done with a competency test prior to the map reading task. The results showed the effectiveness Effectivenessof information retrieval from the three different cartographic images. Conclusions about the efficiency were done concerning the age, gender and level of expertise of the subjects.

Gáspár Albert, Virág Ilyés, Csaba Szigeti, Dávid Kis, Dávid Várkonyi

Interaction Problems Found Through Usability Testing on Interactive Maps

Due to the technological changes beginning in the 1970s, significant advances were seen in the field of cartography, of which the move from analog maps to digital and online ones stands out. This context highlights the importance of obtaining greater efficacy in cartographic communication, permitting the interaction between the user and the content of the map. For interfaces to be developed in an effective way, different approaches must be taken into consideration, one of these is related to the concept of usability. The objective of this study is to analyze the usability Usabilityof the interactive Brazilian maps Geobahia and Geopolis with relation to the use of the data and information they present. To achieve this objective, usability Usabilitytests were carried out with the aim of evaluating the quality of use of the interfacesInterfaces, measured by the ease with which the users concluded their proposed tasks. The tests showed certain difficulties confronted by these users in the realization of proposed tasks that indicate the possible presence of usability problems with these interfaces.

Elaine Gomes Vieira de Jesus, Patricia Lustosa Brito, Vivian de Oliveira Fernandes

The Apprehension of Overlaid Information in a Web Map

Map mashups are now common when presenting information in digital media. This paper explores the relation between the background information (basemap) and the information that is displayed over the basemap. Will the user be disturbed by the background when solving tasks related to the overlaid information? To answer this and other questions, a web-based experiment was prepared. The participants in the experiment were introduced to different tasks based on combinations of data primitives in the top layer. Three different basemapsBasemaps were tested. In a focused part of the experiment, tasks related to the combination of area and points in the top layer were explored more closely. The experiment indicated that the tasks related to different coloured areas in combination with points of different colours were more time consuming to solve on a topographic map with many details.

Dzenan Dumpor, Terje Midtbø

Visualization of Environment-related Information in Augmented Reality: Analysis of User Needs

The main motivation for this study was to enable paraglidingParagliding pilots to use Augmented Reality Augmented realityfeatures during flight. For orientation in the air, paragliding pilots use a map as the main source of information. It is therefore important that the information is presented in the most easily accessible way. The aim of the present study was to investigate the needs of paragliding pilots with respect to maps and the way maps provide them with information about the environment. The participants were three professional paragliding instructors with different amounts of experience. The methods employed involved a semi-structured interview and a practical, real-flight test involving AR glasses; the test was done by only one of the pilots. Two categories of data were identified, with the first involving data related to geographical terrain and the other to the pilot’s immediate surroundings. Our results suggest that an optical see-through displayOptical see-through display would be more suitable for use in the air than the video-based glasses we utilized. If an optical see-through display were used, the terrain could be seen through the glasses, with terrain-related information displayed in the map. AR could be used to present flight-related information as well. Our findings suggest that the way in which information is presented to pilots should be chosen based on the category of the information, namely, whether it is terrain-related or flight-related. In addition, it was found that the small display in the right corner of the pilot’s field of view is rather distractive and insufficient to fulfill the pilots’ needs. Our results also showed that future AR applications should be designed to be transferable between different platforms: glasses, mobile phones, and tablets.

Kateřina Chmelařová, Čeněk Šašinka, Zdeněk Stachoň

Geographic Analysis


Analysis and Visualization of the Urban Residents’ Income-Related Happiness Index in China

Using the Theil index Theil indexand correlation analysis, this paper analyzed the Urban Residents’ Income-Related Happiness Index Happiness indexfrom multiple perspectives, including the current situation, regional disparities, spatial–temporal variationsSpatial–temporal variations, and the mutual relationships of the indicators based on data from 289 prefecture-level cities in China from 2006 to 2015. The results indicated the following: (1) Overall, the Urban Residents’ Income-Related Happiness Index in China was lower in 2015 and was unevenly spread across space. Several cities with higher Income-Related Happiness Index were primarily situated in the southwest region; (2) The within-province disparities were higher than the between-province disparities; (3) For the past 10 years, the Urban Residents’ Income-Related Happiness Index has exhibited an overall downward trend, and the cities that had slight increases in their Income-Related Happiness Index were primarily situated in North China; and (4) The correlation between the Urban Residents’ Income-Related Happiness Index and the per capita gross regional product is not significantly positive. Most cities in China can be categorized into three types: strong happiness–small economic development, weak happiness–large economic development, and weak happiness–small economic development scales. In addition, this study visualized the index analysis results. All of these results are expressed using different maps.

Ying Song, Yang Yu, Yanfang Liu, Zixi Liu, Qianyi Li, Guoguang Xu

Displaying Voter Gains and Losses: Local Government Elections in South Africa for 2011 and 2016

Every five years, the South African population goes to the polls to elect local government councilors. These elections are fought along party lines, however, independent candidates are also allowed to participate. This paper looks at the change of voter behavior between two subsequent local government elections from 2011 and 2016. The percentage voter gains and losses for the top three political parties in South Africa are shown. In the election of 2016, the ruling African National Congress (ANC) party suffered its biggest loss since 1994. The Democratic Alliance (DA) showed an increase in votes between the two elections and, the new kid on the political block, the Economic Freedom Fighters (EFF), showed its biggest gains in the same areas where the ANC showed its largest losses. Three methodologies were used to show these voter behaviors, namely cartogramsCartogram, 3D maps3D maps and thematic cartogram. The latter was used to show both losses and gains in the same cartogram.

Peter M. U. Schmitz

Mapping Community Vulnerability to Poaching: A Whole-of-Society Approach

Wildlife crimeWildlife crime, especially rhinoceros poachingPoaching, is a major problem in South Africa. Approaches to reduce wildlife crime in South Africa range from very sophisticated, near-military interventions to engaging with nearby communities. A method investigated here is the use of a whole-of-societyWhole-of-society approach. This paper investigates the community analysis part of the whole-of-society approach that was used to reduce levels of wildlife crime. Indicators of vulnerability are discussed based on research conducted by several authors and selected on the basis that data can be obtained from generally available sources such as the census. Indicators linked with high levels of risk are identified for communities next to game parks. The goal is to reduce the vulnerability of individuals in these communities to be coerced into wildlife crime by criminal syndicates.

Peter M. U. Schmitz, Duarte Gonçalves, Merin Jacobs

Mapping Urban Landscapes Along Streets Using Google Street View

City streets are a focal point of human activity in urban centers. Citizens interact with the urban environment through its streetscape and it is imperative to, not only map city streetscapes, but quantify those interactions in terms of human well-being. Researchers now have access to fully digitized representation of streetscapes through Google Street View (GSV)Google Street View (GSV), which captures the profile view of streetscapes and, thus, shares equivalent viewing angles with those of the citizen. These two facets—a wealth of streetscape photographs at city-scale and a shared perspective with the end user—underscore the potential of these data in street-level urban landscape Urban landscapemapping. In this study, we introduce two examples that demonstrate GSV as a high-quality data source for mapping street greeneryStreet greenery and openness. First, the modified green view index, which estimates the visibility of street greenery, was applied to static GSV images in order to map the spatial distribution of street greenery. Second, GSV panoramas were used to quantify and map the openness of street canyons by applying a geometrical transformation and image classification Classificationto the panoramas. The results of these two novel applications of street-level photographic data illustrate its utility for quantifying and mapping key urban environmental features at the same viewpoint in which we, as citizens, experience the urban landscape.

Xiaojiang Li, Carlo Ratti, Ian Seiferling

Numerical Analysis


Cross-Scale Analysis of Sub-pixel Variations in Digital Elevation Models

Terrain is modeled on a grid of pixels, assuming that elevation values are constant within any single pixel of a Digital Elevation Model (DEM)Digital elevation models (DEM) (a ‘rigid pixel’ paradigm). This paradigm can generate imprecise measurements because it does not account for the slope and curvature of the terrain within each pixel, leading to precious information being lost. In order to improve the precision of interpolated points, this paper relaxes the rigid pixel assumption, allowing possible sub-pixel variations (a ‘surface-adjusted’ paradigm) to be used to interpolate elevation of arbitrary points given a regular grid. Tests based on interpolating elevation values for 5000 georeferenced random points from a DEM are presented, using theRigid pixel paradigm rigid pixel paradigm and different interpolation methods (e.g., Weighted Average, Linear, Bi-linear, Bi-quadratic, Bi-cubic, and best fitting polynomials) within different contiguity configurationsContiguity configuration (i.e., incorporating first and second order neighbors). The paper examines the sensitivity of surface adjustment to a progression of spatial resolutions (10, 30, 100, and 1000 m DEMs), evaluating sub-pixel variationsSub-pixel variations that can be directly measured from 3 m resolution LIDAR LIDARdata.

Mehran Ghandehari, Barbara P. Buttenfield, Carson J. Q. Farmer

Extraction of Ridge Lines from Grid DEMs with the Steepest Ascent Method Based on Constrained Direction

The extraction of ridge lines from digital elevation models Digital elevation modelsis fundamental for generalizing digital elevation models (DEMDigital elevation models (DEM)), analyzing digital valleys, remote sensing analysis, and topographic indices analysis. In this paper, the authors propose a method to extract ridge linesRidge lines from a gridded DEM called the Steepest Ascent MethodSteepest ascent method Based on Constrained Direction (SAMBCD).SAMBCD In the SAMBCD method, based on the overland flow simulation Overland flow simulationmethod and the steepest ascent method, the authors define control points and constrain the direction of connecting points in the process of organizing major ridge lines and minor ridge lines, respectively, among the discrete points of the catchment boundary. Specifically, with SAMBCD, the points on hill peaks and saddle points are first sorted and used as control points to constrain the connecting direction. Second, the major ridge lines are organized by connecting the relevant discrete points of the catchment boundary, following the constrained direction. Finally, the remaining discrete points of the catchment boundary are connected to form the minor ridge lines with the same constrained connecting direction. Many tests are performed to extract ridge lines in different regions. The results show that the method of SAMBCD is effective for decreasing the fracture, cross and rotation of extracted ridge lines. Moreover, SAMBCD has better performance in the continuity and integrity of ridge lines than the two basic methods mentioned above.

Wenping Jiang, Daping Xi, Xiaolong Deng, Lina Huang, Shen Ying

Using the A Algorithm to Find Optimal Sequences for Area Aggregation

Given two land-cover maps of different scales, we wish to find a sequence of small incremental changes that gradually transforms one map into the other. We assume that the two input maps consist of polygons that constitute a planar subdivision and belong to different land-cover classes. Every polygon in the small-scale map is the union of a set of polygons in the large-scale map. In each step of the sequence that we compute, the smallest area in the current map is merged with one of its neighbors. We do not select that neighbor according to a prescribed rule but define the whole sequence of pairwise merges at once, based on global optimization. An important requirement for such a method is a formalization of the problem in terms of optimization objectives and constraints, which we present together with a solution that is based on the so-called A$$^{\!\star }$$ algorithm. This algorithm allows us to limit the exploration of the search space such that we can compute solutions of high quality in reasonable time. We tested the method with a dataset of the official German topographic database ATKIS and discuss our results.

Dongliang Peng, Alexander Wolff, Jan-Henrik Haunert

Quantitative Expressions of Spatial Similarity in Multi-scale Map Spaces

Spatial similarity Spatial similarityplays an important role in automated map generalizationAutomated map generalization, spatial computations, spatial reasoningSpatial reasoning, spatial retrieval and the construction of multi-scale spatial databases. Nevertheless, the features of spatial similarity relations have never been investigated systematically, yet. To fill the gap, this paper focuses on quantitative expressions of the features of spatial similarity relations in map spacesMap spaces. It firstly summarizes and analyzes the features of similarity in other fields, such as computer science, psychology and geography; then it proposes a number of features of spatial similarity relations in map spaces, i.e., equality, minimality, auto-similarity, symmetry (reflectivity), non-transitivity, triangle inequality, and scale dependency. Mathematical expressions of the features are presented and explained. Finally, potential research issues in spatial similarity relations are reviewed.

Haowen Yan, Liming Zhang, Zhonghui Wang, Weifang Yang, Tao Liu, Liang Zhou

Balanced Allocation of Multi-criteria Geographic Areas by a Genetic Algorithm

The balanced partitioning of geographic space into regions is a common problem. This Territory Design Problem Territory Design Problem(TDP) of assigning smaller areas to larger regions with equal potential is a task mainly done manually. Therefore, the result becomes subjective and provides only a roughly approximated balanced result. This work presents an automated allocation of independent areas to regions using the Genetic Algorithm (GA)Genetic algorithm, which finds an optimally balanced configuration of regions based on multiple criteria. Thereby, spatial constraints are fully respected as (1) all areas remain contiguous within a region and (2) the automated allocation facilitates a compact region shape. The developed algorithm was tested on a case study in the field of sales territory planning. The target of sales territory planning is the optimal distribution of balanced and fair sales areas based on market potentials. Results of our case study demonstrate the effectiveness Effectivenessof our proposed technique to find an optimal structure of sales territories in a reasonable time. The distance that salesmen need to travel is 16% lower than the existing sales territory configuration. This means that the regions are more balanced and more compact. Due to the independent nature of the GA, this method demonstrates a high flexibility to the optimization problem. It can be easily altered to any objective in territory planning as well as to familiar multi-criteria spatial allocation problems in other disciplines.

Shahin Sharifi Noorian, Christian E. Murphy

Rethinking the Buffering Approach for Assessing OpenStreetMap Positional Accuracy

OpenStreetMap (OSM) is a free source of spatial data based on crowd-sourcing. Although OSM data are widely used in applications such as the generation of 3D models, routing and navigation, the quality issue is still one of the significant concerns when using these data. Extensive studies have focused on assessing the quality, especially the positional accuracyPositional accuracy, of OSM data. One method for assessing accuracy is the buffering approachBuffering approach where a buffer is created around a validated road network using a predefined buffer radius. The percentage of OSM road lengths that lie within this buffer is then calculated. While existing studies have used the buffering approach, the method itself has not been evaluated either theoretically and experimentally. It is found that the percentage of OSM road length calculated based on the buffering approach may be imprecise if the validated road network and the OSM road network are not matched one-to-one. Therefore, this study suggests that it is necessary to first match the OSM road network with the validated road network before using the buffering approach.

Qi Zhou

Data Classification for Highlighting Polygons with Local Extreme Values in Choropleth Maps

Following the general demand for task-orientation in map design, one specific task will be examined here: the preservation and highlighting of local extreme values in choropleth Choroplethmaps. Extreme value polygons are ones that show a larger (local maximum) or smaller (local minimum) attribute value compared to all directly neighboring polygons. For a visual identification in a classified choropleth map, such a polygon must belong to a class other than the surrounding polygons. However, data classification Data classificationmethods that are commonly used in the process of generating choropleth maps are data-driven, i.e., the intervals are determined solely on the basis of the present frequency distribution of the original values. With such a division along the number line, the spatial context of the underlying data is completely neglected and with that the desired categorization for local extreme values is not guaranteed. As a consequence, a new method (called PLEX) is presented for this purpose. The application and the effectiveness Effectivenessof this method will be demonstrated using real-world examples.

Jochen Schiewe



A Confidence-Based Approach for the Assessment of Accessibility of Pedestrian Network for Manual Wheelchair Users

An obvious way to assist people with disabilities in their efforts to move around in urban areas is to offer information regarding accessible path segments that take into account their specific needs. Providing safe navigation in urban areas for people with disabilities can substantially enhance their opportunities for full social participation and the exercise of their basic rights. In order to offer these people information on accessible paths, we need to assess the accessibility Accessibilityof pedestrian networksPedestrian networks. Accessibility is the result of interactions between the individual and the environment. These interactions need to be more carefully considered when we evaluate accessibility for persons with disabilities. This paper proposes a new approach for assessing accessibility, based on user confidence while moving around in urban space. For validation purposes, the proposed approach is applied in the Saint-Roch area of Quebec City using confidence information from 127 manual Wheelchair userwheelchair users. The results are presented and discussed and further research perspectives are proposed.

Amin Gharebaghi, Mir-Abolfazl Mostafavi, Geoffrey Edwards, Patrick Fougeyrollas, Patrick Morales-Coayla, François Routhier, Jean Leblond, Luc Noreau

Accessibility in Pedestrian Routing

Pedestrian route planning presents unique challenges compared to relatively well established car routing applications. The challenges are even more pronounced when also considering a diverse user group, which includes people with disabilities. Existing research has identified environmental features that are important to pedestrians with disabilities, but there are still a number of outstanding problems that have hindered the development of a widespread, usable solution. We developed the EUG Access web application ( to implement an approach to pedestrian routing that incorporates environmental accessibility Accessibilityand responds to the needs and preferences of a diverse user population. This paper reviews related literature and reports our experience through three phases of development: personalizationPersonalization, route calculation, and interface design. It concludes by drawing attention to issues that we propose are critical to successfully incorporating environmental accessibility into future pedestrian routing applications.

Megen Brittell, Christine Grummon, Amy Lobben, Masrudy Omri, Nicholas Perdue

Visualization of Traffic Bottlenecks: Combining Traffic Congestion with Complicated Crossings

Daily mobility patterns in highly populated urban environments rely on a well-functioning effective road network. Nevertheless, traffic bottlenecksTraffic bottleneck are typical for urban environments with periodic traffic congestionTraffic congestion. In this paper, we focus on the investigation of how traffic congestion is related with complicated crossingsComplicated crossings. First, we select an approach for the classification Classificationof the complexity of road partitions and the derivation of complicated crossings based on geodata from OpenStreetMapOpenStreetMap (OSM) (OSM). Second, we calculate traffic congestions using Floating Taxi Data (FTD)Floating Taxi Data from Shanghai in 2007. Then, we develop a matching technique to link the congestion and complicated crossings, and subsequently define the concept of traffic bottlenecks represented by polygons. The bottlenecks indicate locations where the transportation infrastructureTransportation infrastructure is complex and traffic congestion appears periodically. Finally, we select suitable cartographic representations of traffic bottlenecks in potential thematic vehicle traffic mapsTraffic maps.

Andreas Keler, Jukka M. Krisp, Linfang Ding

Psychogeography in the Age of the Quantified Self—Mental Map Modelling with Georeferenced Personal Activity Data

Personal and subjective perceptions of urban space have been a focus of various research projects in the area of cartography, geography, and related fields such as urban planningUrban planning. This paper illustrates how personal georeferenced activity dataActivity data can be used in algorithmic modelling of certain aspects of mental mapsMental maps and customised spatial visualisations. The technical implementation of the algorithm is accompanied by a preliminary study which evaluates the performance of the algorithm. As a linking element between personal perception, interpretation, and depiction of space and the field of cartography and geography, we include perspectives from artistic practice and cultural theory.

Sebastian Meier, Katrin Glinka

Final Reflections


In Search of the Essence of Cartography

Discussed here is the essence of cartography as well as the specifics and the uniqueness in the cartographic modellingCartographic modelling process. During the analysis of the theory of cartography and relations to other fields of knowledge, especially philosophy, eight properties of cartographic modelling have been defined which distinguish the process from other methods of space modelling. In attempting to define essential properties of cartographic modelling which would distinguish the process from other methods of space modelling, the authors introduce the notion that the method of cartographic presentation in the form of a map is not limited to graphic representation only. The language of graphic symbols used in classic methods of cartographic presentation is only one form of the cartographic notation of spatial information.

Marek Baranowski, Dariusz Gotlib, Robert Olszewski


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