Auto-Carto 2005 Research Symposium

Forword

E. Lynn Usery and K. Eric Anderson
The Auto-Carto series of meetings began in 1974 at the U.S. Geological Survey National Center in Reston, Virginia, establishing a record of scholarly research in cartography and geographic information systems that became the foundation of geographic information science (GIScience). The Auto-Carto meetings occurred about every two years, culminating with Auto-Carto 13 in 1997.

 By 2005, eight years had expired since the last Auto-Carto meeting and the Cartography and Geographic Information Society Board of Directors was searching for a venue for a scholarly meeting that would be focused on cartography, geo-visualization, and GIScience. With the widespread use of the Internet and the World Wide Web occurring in those eight years, cartography and GIScience had changed dramatically, and the need for a scientific research meeting was again of paramount concern. Recognizing both the need and the changes, the Board decided to hold another Auto-Carto meeting, but rather than continuing the series as Auto-Carto 14, the Board convened the Auto-Carto 2005 Research Symposium. The Symposium was held in March 2005 in Las Vegas, in conjunction with the annual meeting of the American Congress on Surveying and Mapping (ACSM) which had been one of the sponsors of earlier Auto-Carto meetings.

The symposium was an intellectual success, drawing top researchers in cartography and GIScience from the U.S. and around the world. It began with a keynote presentation from Karen Siderelis, Associate Director of the USGS Geospatial Information Office, on the research needs for a National Spatial Data Infrastructure. Dr. Jonathan Raper of City College London gave the second keynote address, on the current move of cartography and GIScience from professionals to the masses, and the need for research to make this transition. The next two days included 50 presentations, with 40 full papers submitted. By all accounts the presentations were excellent, and authors were invited to submit their papers for review in Cartography and Geographic Information Science journal’s review process. Of the 40 papers submitted, 17 passed the rigorous CaGIS review process and are being published in this special issue of the journal.

The Auto-Carto 2005 Research Symposium certainly captured the intellectual energy of the earlier Auto-Carto conferences and we invite you to sample that energy in the papers presented in this issue of Cartography and Geographic Information Science.

We hope you will also join us for Auto-Carto 2006, which will be held June 25-28, 2006, in Vancouver, Washington, at the Heathman Lodge in conjunction with the University Consortium for Geographic Information Science (UCGIS) Summer Assembly. Joining the Auto-Carto 2006 meeting will be the International Cartographic Association Commissions on Generalization, Geo-Visualization, and Map Projections, each of which will hold a workshop on June 25, prior to the beginning of the Auto-Carto 2006 sessions.

After the 2006 Symposium, the CaGIS Board plans to hold the Auto-Carto Research Symposium every two years, in even years, so as not to coincide with the ICA conference. We hope you will thoroughly enjoy this special content issue of Cartography and Geographic Information Science and that you will join us in future Auto-Carto Research Symposia.

VISUALIZATION, WEB SERVICES, MOBILE MAPPING, AND GIS

Visualization of Qualitative Locations in Geographic Information Systems

Xiaobai Yao and Bin Jiang

A qualitative location (QL) refers to the reference of a spatial location using linguistic terms such as qualitative descriptions and qualitative spatial relations with other geo-referenced features. Qualitative locations will be increasingly more popular in the future, driven by theoretical, technological, and database developments. Multiplicity and uncertainty are two innate characteristics of QLs. In other words, a QL often has multiple target locations (multiplicity), and the target locations sometimes cannot be pinpointed exactly due to the qualitative nature (uncertainty) of the qualitative descriptions and relations. The presence of the characteristics imposes research challenges on visualization of QL in geographic information systems (GIS). In response to the visualization challenges we discuss four strategies—namely proportional symbol mapping, fog map, fuzzy 3D surface, and fuzzy-logic-based animation—for the visualization of QL referents in GIS. These strategies combine conventional mapping and advanced interactive visualization methods. Each of them is suitable for one or more scenarios, depending on the presence of either one or both of the two characteristics. All illustrations and related animations are also available at http://www.ggy.uga.edu/people/faculty/xyao/VisQL.html.  Keywords: Visualization, qualitative location, uncertainty, GIS

Gradation as a Communication Device in Area-Class Maps

Barry Kronenfeld

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.

Keywords: Gradation, area-class maps, communication model

Combining Usability Techniques to Design Geovisualization Tools for Epidemiology

Anthony C. Robinson, Jin Chen, Eugene J. Lengerich, Hans G. Meyer, and Alan M. MacEachren

Designing usable geovisualization tools is an emerging problem in GIScience software development. We are often satisfied that a new method provides an innovative window on our data, but functionality alone is insufficient assurance that a tool is applicable to a problem in situ. As extensions of the static methods they evolved from, geovisualization tools are bound to enable new knowledge creation. We have yet to learn how to adapt techniques from interaction designers and usability experts toward our tools in order to maximize this ability. This is especially challenging because there is limited existing guidance for the design of usable geovisualization tools. Their design requires knowledge about the context of work within which they will be used, and should involve user input at all stages, as is the practice in any human-centered design effort. Toward that goal, we have employed a wide range of techniques in the design of ESTAT, an exploratory geovisualization toolkit for epidemiology. These techniques include; verbal protocol analysis, card-sorting, focus groups, and an in-depth case study. This paper reports the design process and evaluation results from our experience with the ESTAT toolkit.

Generalization Services on the Web—Classification and an Initial Prototype Implementation

Dirk Burghardt, Moritz Neun, and Robert Weibel

Much progress has been made in the field of web-based cartography through standards developed by the Open Geospatial Consortium (OGC). While automated access and presentation of cartographic data have been defined, the services for automated generalization are yet to be standardized. This paper aims to show advantages of applying the service concept to generalization and suggests several classification schemas of generalization services at different levels of granularity. A detailed explanation of a real implemented Generalization Service is provided. We show how software developers can make their generalization functionality available as a service and how these services can be accessed dynamically. For the implementation, the open source Java Unified Mapping Platform (JUMP) was extended to work as a framework for generalization. Generalization services could be used in different application scenarios, for instance as a middleware component extending a web map service with adaptive zooming or as stand-alone services supporting the production of topographic maps by national mapping agencies. They may also allow the development of a common research platform, where researchers would have access to a common generalization framework.

The Roles of Web Feature and Web Map Services in Real-time Geospatial Data Sharing for Time-critical Applications

Chuanrong Zhang  and Weidong Li

Many time-critical applications such as emergency response, location-based services, and real time traffic management need instant access to diverse data to make quick decisions and take instantaneous actions. However, two issues block time-critical applications to quickly acquire and integrate spatial data over the web: (1) the heterogeneity of existing GIS systems, and (2) the file-level data sharing systems over the web. This research examines current open standards, protocols, and technologies capable of solving the two issues for real-time spatial data sharing over the web. Focusing on investigating the role of Web Feature Services (WFS) and Web Map Services (WMS), this research has developed a solution for real-time geospatial data sharing at the feature level over the web. A prototype has been implemented to query, extract, create, delete, update, and map geographic features stored in web-accessible OGC (Open Geospatial Consortium) simple feature datastores for transportation emergency applications. The prototype results show that the OGC WFS and WMS play important roles in real-time geospatial data sharing and exchange from heterogeneous sources at the feature level for time-critical applications. The WFS and WMS eliminate time-consuming data translation and facilitate reuse of existing geospatial data over the web. Several issues related to the solution are also discussed in the paper.

Map Design Evaluation for Mobile Display

Julie Dillemuth

How to effectively represent spatial information on handheld mobile devices is a key question, given the increasing use of personal digital assistants (PDAs) and cell phones concurrent with the development of location-based services. The mobile use of digital maps on small displays presents new capabilities and challenges that differ from using paper maps in a mobile setting or viewing digital maps on a desktop computer. This research addresses these issues through a study that evaluated maps on a mobile device used for a field-based navigation task. Map representations at two levels of generalization were compared by analyzing subject performance in a pedestrian route-following task, in which a handheld computer was used as a navigation aid. Subject time and accuracy as well as interaction with the mobile device during the task were measured. The results carry implications for map design for small, mobile displays and identify factors that affect the use of maps while moving.  Maps are and will increasingly be used on small displays in mobile contexts for a variety of purposes and in many different environments. The requirements and preferences of mobile users, as well as how these maps are used in different contexts, must be understood in order to inform more effective designs.

DATA MODELS AND ALGORITHMS

Towards a 3D Feature Overlay through a Tetrahedral Mesh Data Structure

Edward Verbree, Arno van der Most, Wilko Quak, and Peter van Oosterom

The use of 3D features within GIS has been increasing due to the need to represent, query, manipulate, and analyze man-made objects in relationship to other 3D features related to the surface of the earth. This will yield an increased use of 3D boundary representations of the features. The spatial relationship between two or more features is often evaluated using a geometrical overlay of these features, which reveals whether these features overlap and—if they do—to which extent. We present the design of a 3D overlay algorithm which overlays 3D triangulated boundary representations through a constrained tetrahedral mesh. The intersections between the constrained facets of the 3D features are calculated on the fly and within a restricted neighborhood. We can identify and reconstruct the overlaid parts of the 3D boundary representation within the tetrahedral mesh. The implementation is based on the Computational Geometry Algorithms Library, which proved to have the functionality needed but also has its limitations.Keywords: Triangular mesh, tetrahedral mesh, overlay algorithms

A Prototype Temporal GIS for Multiple Spatio-Temporal Representations

Yanfen Le

Development of a temporal geographic information system (GIS) and spatio-temporal data modeling are key to incorporating time into geographic information science. This paper describes how to design and develop temporal GIS that will work with spatio-temporal data represented in various data models, and it introduces a prototype temporal GIS with a case study. In temporal GIS, the integration of multiple spatio-temporal representations is based on common spatial and temporal reference systems. In other words, a map window of temporal GIS visualizes spatio-temporal data valid at the same time within one spatial area. To achieve such visualization, separate data editing and query modules are required for each spatio-temporal data model (STDM). In the temporal query interface, after a user specifies a time, the system automatically hires correspondent modules to retrieve spatio-temporal data valid at that time. Besides temporal queries common to all STDMs, each module may provide additional temporal query capabilities specific to that STDM. In the case study, I implement a prototype temporal GIS for three STDMs. The examples of query and visualization, which use three datasets (census data, land use/land cover, and elevation data) demonstrate the prototype temporal GIS can integrate multiple temporal representations.

Keywords:  Temporal, GIS, multiple, representation

Variable-scale Topological Data Structures Suitable for Progressive Data Transfer: The GAP-face Tree and GAP-edge Forest

Peter van Oosterom

This paper presents the first data structure for a variable scale representation of an area partitioning without redundancy of geometry. At the highest level of detail, the areas are represented using a topological structure based on faces and edges; there is no redundancy of geometry in this structure as the shared boundaries (edges) between neighbor areas are stored only once. Each edge is represented by a Binary Line Generalization (BLG)-tree, which enables selection of the proper representation for a given scale. Further, there is also no geometry redundancy between the different levels of detail. An edge at a higher importance level (less detail) does not contain copies of the lower-level edges or coordinates (more detail), but it is represented by efficiently combining their corresponding BLG trees. Which edges have to be combined follows from the generalization computation, and this is stored in a data structure. This data structure turns out to be a set of trees, which will be called the (Generalized Area Partitioning) GAP-edge forest. With regard to faces, the generalization result can be captured in a single tree structure for the parent-child relationships—the GAP face-tree. At the client side there are no geometric computations necessary to compute the polygon representations of the faces, merely following the topological references is sufficient. Finally, the presented data structure is also suitable for progressive transfer of vector maps, assuming that the client maintains a local copy of the GAP-face tree and the GAP-edge forest. Keywords: Map generalization, topological structure, planar partition, client/server, progressive data transfer, geo-information system

Supporting the Comparison of Choropleth Maps Using an Evolutionary Algorithm

Ningchuan Xiao and Marc P. Armstrong

Choropleth maps can be used to compare the patterns exhibited by different spatial variables. In this paper, we develop an evolutionary algorithm that can be used to generate classifications that allow a user to explore the spatial patterns of multiple choropleth maps in terms of their visual correlation and the equality of area contained in each class. Synthetic and census data are used to demonstrate the effectiveness of our approach. Keywords: Choropleth mapping, visual correlation, multi-objective optimization, visualization

Exploring the Hidden Potential of Common Spatial Data Models to Visualize Uncertainty

Julian Kardos, Antoni Moore, and George Benwell

Common Spatial Data Models (SDMs) such the vector, raster, and quadtree have well understood and widely practiced conventions of storage and visualization. This paper explores what happens when the conventions of visualization are not strictly adhered to, and the SDMs are used in an atypical fashion. A framework based on a quasi similarity measure is presented, which quantifies (in terms of “distance”) the relationship between the storage format and the visualization output, following an accepted protocol. This research used a transformation process (Tp) to define this distance. Then, the atypical use of the quadtree SDM to represent choropleth spatial boundary uncertainty and attribute uncertainty was quantified using the same framework. This research shows that if a SDM is used outside of its original context, then the distance between the storage format and its visual output can alter; in our case, the distance decreased. This result was interpreted as evidence for the creation of a new spatial data structure. The formalization of the relationship between an SDM and its visual output will be valuable for future exploration of the non-conventional visualization of common SDMs. Keywords: Spatial data model, storage, display, uncertainty, transformation

An Artificial-Neural-Network-based, Constrained CA Model for Simulating Urban Growth  

Qingfeng Guan, Liming Wang, and Keith C. Clarke

Insufficient research has been done on integrating artificial-neural-network-based cellular automata (CA) models and constrained CA models, even though both types have been studied for several years. In this paper, a constrained CA model based on an artificial neural network (ANN) was developed to simulate and forecast urban growth. Neural networks can learn from available urban land-use geospatial data and thus deal with redundancy, inaccuracy, and noise during the CA parameter calibration. In the ANN-Urban-CA model we used, a two-layer Back-Propagation (BP) neural network has been integrated into a CA model to seek suitable parameter values that match the historical data. Each cell’s probability of urban transformation is determined by the neural network during simulation. A macro-scale socio-economic model was run together with the CA model to estimate demand for urban space in each period in the future. The total number of new urban cells generated by the CA model was constrained, taking such exogenous demands as population forecasts into account. Beijing urban growth between 1980 and 2000 was simulated using this model, and long-term (2001-2015) growth was forecast based on multiple socio-economic scenarios. The ANN-Urban-CA model was found capable of simulating and forecasting the complex and non-linear spatial-temporal process of urban growth in a reasonably short time, with less subjective uncertainty. Keywords: Constrained cellular automata, artificial neural network, urban growth

Design Considerations for Haptic and Auditory Map Interfaces

Matt Rice, R. Daniel Jacobson, Reginald G. Golledge, and David Jones

Communicating spatial information to the blind and visually impaired using maps and graphics presents many difficulties. Past research has offered advice to cartographers on topics such as tactile areal, point, and line symbolization; on perceptual problems related to dense linear features on tactile maps; and on the relationship between categorical data, measurement theory, and tactile discrimination. With this previous work as a foundation, we describe our research efforts with haptic and auditory maps—the Haptic Soundscapes Project. Haptic Soundscapes maps allow blind and visually-impaired individuals to feel map features through force feedback devices and hear auditory cues that add both redundant and complementary information. Recent experimental work by the authors has led to several recommended practices for cartographic data simplification, object size discrimination, shape identification, and general interface navigation. The authors also present haptic and auditory mapping examples to illustrate design ideas, algorithms, and technical requirements. Future prospects for automated haptic and auditory map creation are discussed and presented in the context of the past work in generating maps for the blind and visually impaired from cartographic data.

ACCURACY, REPRESENTATION, AND INTERPOLATION

Assessing Resampling Accuracy of Categorical Data Using Random Points

Jeong Chang Seong

Tissot’s Indicatrix and regular grids have been used for assessing map projection accuracies. Despite their broad applicability for accuracy assessment, they have limitations in quantifying resampling errors caused by map projections. This is due to the structural uncertainty with regard to the placement and pattern of grids. It is also difficult to calculate the absolute amount of resampling error in each projection. As an alternative to traditional testing methods, the use of random points was investigated. Specifically, random point generation, resampling with spherical block search algorithms, resampling accuracy with a perfect grid, and resampling accuracy with eight projections were investigated and are discussed here. Eight global referencing methods were tested: the equal-area cylindrical, sinusoidal, Mollweide, Eckert IV, Hammer-Aitoff, interrupted Goode homolosine, integerized sinusoidal projections, and the equal area global gridding with a fixed latitudinal metric distance. The resampling accuracy with a perfect grid is about 75 percent. Results showed the sinusoidal and the integerized sinusoidal projections and equal-area global gridding to achieve the highest accuracies. Keywords: Resampling accuracy, map projection, random points, global raster database

Lidar Elevation Data for Surface Hydrologic Modeling: Resolution and Representation Issues

Christopher P. Barber and Ashton Shortridge

This paper is concerned with the application of high spatial resolution elevation data derived from light detection and ranging technologies (lidar) to surface hydrologic modeling. In recent years, airborne lidar technology has been employed to develop high accuracy digital elevation models (DEMs) with horizontal resolution on the order of a few meters. As with any spatial data product there are limits to the lidar’s practical use that vary with the intended application. This paper considers potential issues and challenges for the use of lidar-derived DEMs in surface hydrologic modeling applications, such as characterizing flow direction and power, identifying sub-basins in a watershed, and calculating upstream contributing area and other variables.  We compare results using conventional 30m DEMs and 6m lidar for a high relief study area and a low relief study area.  Results are more comparable between these data sources, regardless of hydrologic operation, for the high relief area, while the similarity of results in the low relief area is dependent upon the particular operation. Post-processing on the lidar data successfully removed such flow obstacles as bridges that might have artificially impeded surface flow.  An exploration of the effect of spatial resolution on results suggests that cell size is a more significant factor than production method.

A Comparative Analysis of Areal Interpolation Methods

Kevin Hawley and Harold Moellering

Over the years many approaches to areal interpolation have been developed and utilized.  They range from the simple 2-D areal weighing method which uses only the spatial Z variable being processed, to more sophisticated approaches which use auxiliary variable(s) to provide more specificity to the results. In the research reported here, four promising approaches are implemented and comparatively tested. These approaches have widely varying conceptual foundations, and different auxiliary variables, if used. The areal weighing reflects many earlier methods which assumes uniform distribu­tions of the spatial Z variable, and does not use any auxiliary variable. Tobler’s pycnophylactic method uses a volumetric preservation approach, which assumes spatial Z variable is heterogeneously distribut­ed, but does not use any auxiliary variable. The traditional dasymetric method of Wright is used with remote sensing spectral data of land use. Xie’s road network hierarchically weighted interpolation uses the road network as the auxiliary variable, and assumes that population density is related to the class of the road, and to the density of the road network. The research design implemented here uses Census population distributions at different levels in the hierarchy as the source and target variables analyzed.  The source zone population is taken at the Census Tract level, and the target zones are specified at the Census Block Group level in the hierarchy.  The first two tests use only the Census population Z data, and no auxiliary variables, whereas the next uses remotely sensed land use data as the auxiliary data variable, and the fourth test utilizes the road network hierarchy as the auxiliary variable. The paper reports on the findings from these tests, and then interprets them in a spatial setting in terms of accuracy and effectiveness. This research points to the network method as the most accurate of the areal interpolation methods tested in this research.

SOCIETY AND HISTORY

Communities of Scholars: Places of Leverage in the History of Automated Cartography

Nicholas R. Chrisman

The search for “origins” in the history of technology is often disappointing. Each origin uncovers some predecessors vanishing into the mists. More importantly, the distinct competitors turn out to be much more entwined than imagined. This paper will describe the community into which automated cartography emerged. Being “first” is only something that is apparent in retrospect. It makes sense to remember a bit more about the pre-history of geographic information systems, not just to get the history right, but to understand how the events of prior periods influence the way the technology develops. Current developments may owe much to forgotten or misremembered pasts. This paper examines the 1960s with the development of the Canada Geographic Information System (CGIS) by Roger Tomlinson. It then turns to the circumstances that preceded the development of CGIS, particularly at the University of Washington. From this examination, it is apparent that the construction of a community is more important than determining who did what first. This community emerges from documents and artifacts of the period.