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The development of micro level models of urban processes has partially been facilitated by increased availability of detailed activity/travel survey data. Managing and exploring these data can be resource intensive and time consuming. Researchers and municipal planning organizations increasingly face information management challenges. This paper reviews an experiment in design and implementation of an object-relational geographic database using the principles of object-orientation. A data model is specified using the Unified Modeling Language notation and a visual modeling tool, and then implemented as an object-relational spatial database. The resulting database acts as an information foundation capable of supporting empirical research and application development. The experience suggests that a formal approach to information management can enhance our understanding of complex activity/travel data contributing to informed application of these data to transportation research questions.The authors would like to thank Metro for the provision of data and supporting documentation. They are also thankful to three anonymous reviewers for their constructive comments. The second author, holder of the Canada Research Chair in Spatial Analysis, is grateful for the support of the SSHRC Canada Research Chairs program. 相似文献
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Raja Sengupta Griet Vankeerberghen Ruoxuan Wen Jing Rao Yanbing Chen 《Transactions in GIS》2023,27(4):1090-1103
GIS-enabled historiography allows us to shed light on missing or poorly understood aspects of historical events. Here, we use agent-based models (ABMs), least cost path analysis (LCPA), and space–time paths to recreate and evaluate possible modes and routes of travel undertaken by Shi Rao, a Western Han official. A diary was found in Shi Rao's tomb that includes information about his travels over 1 year (11 BCE), including start and end times of his journeys. But it leaves out details regarding modes of transport or exact routes. Using Tan Qixiang's historical atlas, we digitized river networks and utilized modern topographic data to digitally recreate the landscape as it was during Shi Rao's travels. This was then used to evaluate possible journeys via rivers (using ABMs) and roads (using LCPA), and compared to historical speed of boats, carts and horses, with findings indicating that horseback may have been the viable option. 相似文献
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《The Cartographic journal》2013,50(1):85-86
AbstractThis paper is the substance of a talk on the Impact of Inflation on Cartography, given to the British Cartographic Society in January 1976. The difficulty of the subject is evident from the many causes of inflation and because of the speed at which inflation was and is affecting every aspect of life. However, the subject has a fascinating horror and is so pertinent that the contemporary value of such a paper is great. 相似文献
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Daniel G. Brown Rick Riolo Derek T. Robinson Michael North William Rand 《Journal of Geographical Systems》2005,7(1):25-47
The use of object-orientation for both spatial data and spatial process models facilitates their integration, which can allow exploration and explanation of spatial-temporal phenomena. In order to better understand how tight coupling might proceed and to evaluate the possible functional and efficiency gains from such a tight coupling, we identify four key relationships affecting how geographic data (fields and objects) and agent-based process models can interact: identity, causal, temporal and topological. We discuss approaches to implementing tight integration, focusing on a middleware approach that links existing GIS and ABM development platforms, and illustrate the need and approaches with example agent-based models. 相似文献
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The cartogram, or value-by-area map, is a popular technique for cartographically representing social data. Such maps visually equalize a basemap prior to mapping a social variable by adjusting the size of each enumeration unit by a second, related variable. However, to scale the basemap units according to an equalizing variable, cartograms must distort the shape and/or topology of the original geography. Such compromises reduce the effectiveness of the visualization for elemental and general map-reading tasks. Here we describe a new kind of representation, termed a value-by-alpha map, which visually equalizes the basemap by adjusting the alpha channel, rather than the size, of each enumeration unit. Although not without its own limitations, the value-by-alpha map is able to circumvent the compromise inherent to the cartogram form, perfectly equalizing the basemap while preserving both shape and topology. 相似文献
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Surendra Sunda Sneha Yadav R. Sridharan M. S. Bagiya P. V. Khekale Pan Singh S. V. Satish 《GPS Solutions》2017,21(4):1469-1478
With the increase in the use of satellite-based navigation services, the forecasting of L band scintillation has turned out to be of paramount importance as it affects their accuracy and availability. Forecasting the time of occurrence or non-occurrence, strength and probable location of scintillation enables the service providers and users to take appropriate action to mitigate the effects and optimize the services. We use the recently developed method to retrieve TEC from the ionospheric correction data transmitted by the Indian satellite-based augmentation system (SBAS)–GAGAN. By making use of the established linear relation between the dusk time TEC and the maximum probable scintillation intensity (S4max), scintillation forecast maps have been generated as early as 1930 LT. The superposition of actual S4 measurements, obtained from the GAGAN network of receivers, on the forecasted S4max map shows that the actual measurements are less than the predicted S4max except on very few occasions. The potential of the simple technique to predict the 2 D maps of maximum probable scintillation index for the whole night has been demonstrated which with more refinements could evolve into a viable forecast or forewarning system. 相似文献
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《ISPRS Journal of Photogrammetry and Remote Sensing》1999,54(4):234-243
A geologic map is typically a 2D representation of 3D subsurface structures in a given area. It is based on the currently accepted geologists' model explaining the observed phenomena and the processes that shaped them in the geologic past. For historical reasons, this model is recorded in a geologic map with an explanatory booklet that describes the authors' conclusions as well as relevant field observations and other data such as tectonic measurements, drill hole logs or fossil records. Today, however, this variety of information can be better handled by converting it into digital and even hypermedial format. This necessitates the prior conception, development and implementation of a suitable geologic “hypermap model”. The main objective of this study is to design models and tools well-suited for the interaction between users and geologic hypermaps. The unique aspect of this family of applications is that users, in general, are both end-users (e.g., engineers) and designers (e.g., mapmakers). Objectives, concepts and methods for developing a human interface to geologic hypermaps have been tested using a prototype (i.e., GeoHyp) within the GIS environment of ArcView from ESRI. Tools to access the underlying background database via hyperlinks have been implemented, as well as functions especially developed to meet specific geologic requirements. Tests with various types of users have shown that the prototype matches their expectations and serves as a good basis for further development. In this article, we report on our design choices for GeoHyp and the current status of our project. 相似文献
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本文从地图制图专业视角出发,归纳互联网地图制图体系的要素及其关系,分析目前地图视觉质量仍待优化的必要性,并揭示现状问题的成因。进而结合互联网地图的特点、媒介环境和技术条件、受众认知与交互需求等,提出影响互联网地图视觉质量的用户考量、研究倾向、参与协同和介质技术等四大因素。由此,强调美学属性是地图必要的有机组分,网络地图服务的功能体验、交互体验、视觉体验相辅相成。最后,基于以用户为中心和跨学科协同的理念,回答了制图实践的方向性问题,从宏观指导、具体原则和实施细节三个层面,探讨了互联网地图视觉质量控制和优化设计的对策建议。 相似文献
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Trip making, induced travel demand, and accessibility 总被引:2,自引:1,他引:1
Traditional transportation planning practice rests on the premise that the demand for transportation is derived. On the other hand, economic theory advances that enhancement to the transportation system leads to lower travel cost and hence to induced demand. Such an argument lends support to the view that the rate at which trips are generated is linked to the ease of making trips to potential destinations. Rather conflicting evidence has so far come out of aggregate trip generation modeling applications. This paper revisits this issue with proper characterization of integral accessibility. Poisson regression models of automobile trip generation by trip purpose are estimated on travel survey data in Minneapolis–St. Paul, MN. Alternative measures of accessibility are tested for statistical significance. Conclusions are drawn on the role of accessibility in trip making and on the comparison of integral accessibility measures.The first author gratefully acknowledges the financial support of NSF grant SBR- 9308394. We are particularly indebted to Rick Gelbmann, Robert Paddock, and Mark Philippi at the Metropolitan Council, Minneapolis–St. Paul, and William Barrett at the Office of Transportation Data Analysis, Minnesota Department of Transportation for their availability to answer all our data-related questions. 相似文献
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Categorical maps, comparisons, and confidence 总被引:2,自引:0,他引:2
The comparison of categorical maps is a common problem in several different contexts. Differences between categorical maps can be characterized and measured in a variety of ways. In 2004 we invited individuals from remote sensing, geographical information analysis, spatial modelling, and landscape ecology to participate in a virtual workshop in order to compare strategies for comparison. This revealed that the key dimensions of comparison relate to (1) the map characteristics considered, (2) the nature of the comparison, (3) the handling of geographical space, (4) the units of computed measures, and (5) the tests of significance.Ferko Csillag deceased 相似文献
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Ian Muehlenhaus 《制图学和地理信息科学》2013,40(5):401-414
Persuasive maps are ubiquitous in society, yet cartographers have largely neglected to conduct serious, holistic research on them. Persuasive maps represent a form of visual communication that differs markedly from scientific geovisualization. First, many of these maps' communicative goals are anathema to those of scientific representation. Second, many persuasive maps ignore and defy established cartographic conventions. This article argues two things. First, the cartographic discipline can gain insight about how maps communicate information from the longitudinal and holistic analysis of persuasive maps. By comparing the differences and similarities of persuasive maps to scientific geovisualizations, researchers can begin to understand how persuasive maps communicate differently than scientific ones. Second, breaking persuasive maps down into composite parts may make it possible to identify persuasive map norms (i.e., methods of design that are embraced by producers of persuasive maps). The results of a content analysis of 256 persuasive maps are discussed. The article concludes that it may be possible to take the most statistically significant results from this study to begin identifying different rhetorical styles of persuasive maps. 相似文献
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Transmission and visualization of large geographical maps 总被引:1,自引:0,他引:1
Liqiang Zhang Liang ZhangYingchao Ren Zhifeng Guo 《ISPRS Journal of Photogrammetry and Remote Sensing》2011,66(1):73-80
Transmission and visualization of large geographical maps have become a challenging research issue in GIS applications. This paper presents an efficient and robust way to simplify large geographical maps using frame buffers and Voronoi diagrams. The topological relationships are kept during the simplification by removing the Voronoi diagram’s self-overlapped regions. With the simplified vector maps, we establish different levels of detail (LOD) models of these maps. Then we introduce a client/server architecture which integrates our out-of-core algorithm, progressive transmission and rendering scheme based on computer graphics hardware. The architecture allows the viewers to view different regions interactively at different LODs on the network. Experimental results show that our proposed scheme provides an effective way for powerful transmission and manipulation of large maps. 相似文献
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ABSTRACTDot maps have become a popular way to visualize discrete geographic data. Yet, beyond showing how the data are spatially distributed, dot maps are often visually cluttered in terms of consistency, overlap, and representativeness. Existing clutter reduction techniques like jittering, refinement, distortion, and aggregation also address this issue, but do so by arbitrarily displacing dots from their exact location, removing dots from the map, changing the spatial reference of the map, or reducing its level of detail, respectively. We present BinSq, a novel visualization technique to compare variations in dot density patterns without visual clutter. Based on a careful synthesis of existing clutter reduction techniques, BinSq reduces the wide variety of dot density variations on the map to a representative subset of density intervals that are more distinguishable. The subset is derived from a nested binning operation that introduces order and regularity to the map. Thereafter, a dot prioritization operation improves the representativeness of the map by equalizing visible data values to correspond with the actual data. In this paper, we describe the algorithmic implementation of BinSq, explore its parametric design space, and discuss its capabilities in comparison to six existing clutter reduction techniques for dot maps. 相似文献
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Numerous studies attempted to associate search engine data with travel behaviors. However, most existing studies focus on the destinations of search and travel, while ignoring the origins, which embed critical information of where the search requests were initiated and where the travelers came from. In this study, we explore the relationships between two types of intercity origin–destination flow data, namely travel flows and search flows, which, respectively, record the number of travelers and search requests from one city towards another. By comparing the two flows during holiday and non-holiday, we examine their complex spatiotemporal relationships from multiple perspectives, including time-lag effect, distance decay effect, spatial autocorrelation, network community, cities' rankings, and important factors of search and travel activities. The findings can deepen our understanding of search and travel behaviors, hence they can help decision makers to develop targeted strategies to enhance city's attractiveness, improve transportation infrastructure, and promote tourism. 相似文献
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