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1.
Deniz Karagulle Charlie Frye Roger Sayre Sean Breyer Peter Aniello Randy Vaughan Dawn Wright 《Transactions in GIS》2017,21(5):1040-1060
In 1964, E.H. Hammond proposed criteria for classifying and mapping physiographic regions of the United States. Hammond produced a map entitled “Classes of Land Surface Form in the Forty‐Eight States, USA”, which is regarded as a pioneering and rigorous treatment of regional physiography. Several researchers automated Hammond?s model in GIS. However, these were local or regional in application, and resulted in inadequate characterization of tablelands. We used a global 250 m DEM to produce a new characterization of global Hammond landform regions. The improved algorithm we developed for the regional landform modeling: (1) incorporated a profile parameter for the delineation of tablelands; (2) accommodated negative elevation data values; (3) allowed neighborhood analysis window (NAW) size to vary between parameters; (4) more accurately bounded plains regions; and (5) mapped landform regions as opposed to discrete landform features. The new global Hammond landform regions product builds on an existing global Hammond landform features product developed by the U.S. Geological Survey, which, while globally comprehensive, did not include tablelands, used a fixed NAW size, and essentially classified pixels rather than regions. Our algorithm also permits the disaggregation of “mixed” Hammond types (e.g. plains with high mountains) into their component parts. 相似文献
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C. L. Ogleby 《The Photogrammetric Record》1999,16(94):651-670
For in excess of 100 years, photogrammetry has played a significant role in documenting the cultural heritage of nations and peoples. Many recent advances in the technique have enhanced the use of photogrammetry as a recording tool, enabling more complex representations of objects and moving access to the procedure from the expert to the interested user. Some of these recent developments include low cost digital photogrammetric systems, image sequence analysis, bundle adjustment and camera calibration procedures, and three dimensional laser scanning. An overview of some of these developments is given in this paper. The University of Melbourne, in conjunction with Chulalongkorn University in Bangkok, has been working on a project to create a computer visualization of the ancient Thai city of Ayutthaya. This project has blended three dimensional CAD models of the architectural features of Ayutthaya with historical research and artistic rendering to build a realistic representation of this city as it may have existed in the past. The model of the city has been built up from historical “maps”, aerial photographs, field survey and the use of photogrammetry to derive models of individual wat, chedi, prang (see GLOSSARY) and statuary. The historical research conducted in Thailand has provided the basis for the determination of the most likely location and appearance of the missing structures. The CAD models created from the photogrammetry have been visualized by the addition of surface textures and materials and rendered in as realistic a manner as possible. The virtual city has also been augmented by the incorporation of live actors in the computer reconstruction. When completed, the end product will be capable of producing an experience of daily life in Ayutthaya, with the potential for giving the user a level of interaction. The reconstruction will also be used as the basis of a variety of educational products to be produced in Thailand on a number of different media, including a bilingual CD-ROM already developed to “proof-of-concept” stage. 相似文献
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With the rapid growth and popularity of mobile devices and location‐aware technologies, online social networks such as Twitter have become an important data source for scientists to conduct geo‐social network research. Non‐personal accounts, spam users and junk tweets, however, pose severe problems to the extraction of meaningful information and the validation of any research findings on tweets or twitter users. Therefore, the detection of such users is a critical and fundamental step for twitter‐related geographic research. In this study, we develop a methodological framework to: (1) extract user characteristics based on geographic, graph‐based and content‐based features of tweets; (2) construct a training dataset by manually inspecting and labeling a large sample of twitter users; and (3) derive reliable rules and knowledge for detecting non‐personal users with supervised classification methods. The extracted geographic characteristics of a user include maximum speed, mean speed, the number of different counties that the user has been to, and others. Content‐based characteristics for a user include the number of tweets per month, the percentage of tweets with URLs or Hashtags, and the percentage of tweets with emotions, detected with sentiment analysis. The extracted rules are theoretically interesting and practically useful. Specifically, the results show that geographic features, such as the average speed and frequency of county changes, can serve as important indicators of non‐personal users. For non‐spatial characteristics, the percentage of tweets with a high human factor index, the percentage of tweets with URLs, and the percentage of tweets with mentioned/replied users are the top three features in detecting non‐personal users. 相似文献
5.
Matthew Haffner 《Transactions in GIS》2018,22(4):913-929
The use of social media data in geographic studies has become common, yet the question of social media's validity in such contexts is often overlooked. Social media data suffers from a variety of biases and limitations; nevertheless, with a proper understanding of the drawbacks, these data can be powerful. As cities seek to become “smarter,” they can potentially use social media data to creatively address the needs of their most vulnerable groups, such as ethnic minorities. However, questions remain unanswered regarding who uses these social networking platforms, how people use these platforms, and how representative social media data is of users' everyday lives. Using several forms of regression, I explore the relationships between a conventional data source (the U.S. Census) and a subset of Twitter data potentially representative of minority groups: tweets created by users with an account language other than English. A considerable amount of non‐stationarity is uncovered, which should serve as a warning against sweeping statements regarding the demographics of users and where people prefer to post. Further, I find that precisely located Twitter data informs us more about the digital status of places and less about users' day‐to‐day travel patterns. 相似文献
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This study demonstrates the potential value, and difficulties, in utilizing large‐scale, location aware, administrative data together with urban modeling to address current policy issues in a timely fashion. We take advantage of a unique dataset of millions of odometer readings from annual safety inspections of all private passenger vehicles in Metropolitan Boston to estimate the vehicle‐miles‐traveled (VMT) implication of alternative metropolitan growth scenarios: a sprawl‐type “let‐it‐be” scenario and a smart‐growth‐type “winds‐of‐change” scenario. The data are georeferenced to 250 × 250 m grid cells developed by MassGIS. We apply a greedy algorithm to assign Traffic Analysis Zone (TAZ) level household growth projections to grid cells and then use spatial interpolation tools to estimate VMT‐per‐vehicle surfaces for the region. If new growth households have similar VMT behavior as their neighbors, then the let‐it‐be scenario will generate 12–15% more VMT per household compared to the winds‐of‐change scenario. However, even the “wind‐of‐change” scenario, will result in new households averaging higher VMT per household than the Metro Boston average observed in 2005. The implication is that urban growth management can significantly reduce GHG but, by itself, will not be sufficient to achieve the GHG emission reduction targets set by the State for the transportation sector. 相似文献
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Miriam Baglioni Emiliano Giovannetti Maria Vittoria Masserotti Chiara Renso Laura Spinsanti 《Transactions in GIS》2008,12(Z1):31-44
Querying geographical information systems has been recognized as a difficult task for non‐expert users. Furthermore, user queries are often characterized by semantic aspects not directly managed by traditional spatial databases or GIS. Examples of such semantic geospatial queries are the use of implicit spatial relations between objects, or the reference of domain concepts not explicitly represented in data. To handle such queries, we envisage a system that translates natural language queries into spatial SQL statements on a database, thus improving standard GIS with new semantic capabilities. Within this general objective, the contribution of this article is to introduce a methodology to handle semantic geospatial queries issued over a spatial database. This approach captures semantics from an ontology built upon the spatial database and enriched by domain concepts and properties specifically defined to represent the localization of objects. Some examples of the use of the methodology in the urban domain are presented. 相似文献
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Interplay between urban communities and human‐crowd mobility: A study using contributed geospatial data sources 
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下载免费PDF全文 An intense process of urbanization, witnessed particularly in the last decade, has stressed the need to comprehend human mobility behavior in urban settings. Although the emergence of contributed geospatial data (i.e., pervasive activity‐based data) has contributed to substantial progress toward understanding human activity, the relationship between human‐crowd mobility and the functional structure of a city is not yet well understood. In this context, the present research focuses on the intra‐urban origin–destination matrix modeling founded on a combination of two major crowdsourced datasets as well as the inclusion of urban communities’ structure. Specifically, the well‐known “radiation” and “PWO” models were modified through first, identifying the communities embedded in the cyberspace network then employing the identified hierarchical structure of the spatial‐interaction network for the formulation of the users’ movement network and second, imposing proper input variables including the telecommunication activity volume and check‐in frequency. The results obtained by various empirical analyses suggest that the modified community‐constrained origin–destination flow estimation models exhibit better performance levels than those of alternative conventional mobility models. 相似文献
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Blogs, micro‐blogs and online forums underpin a more interconnected world. People communicate ever more and are increasingly keen to explain and illustrate their lives; showing where they are and what they are doing. Desktop, online and mobile mapping landscapes have never been as rich or diverse yet this challenges cartography to adapt and remain relevant in the modern mapping world. We explore the spatial expression and potential value of micro‐blogging and Twitter as a social networking tool. Examples of “twitter maps” are reviewed that leverage the Twitter API and online map services to locate some component of the “tweet”. Scope, function and design are illustrated through development of two proof‐of‐concept map mashups that support collaborative real‐time mapping and the organisation and display of information for mass user events. Through the experiments in using and organising data in this way we demonstrate the value of “cartoblography”– a framework for mapping the spatial context of micro‐blogging. 相似文献
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The Annotation Process in OpenStreetMap 总被引：2，自引：1，他引：1
In this article we describe the analysis of 25,000 objects from the OpenStreetMap (OSM) databases of Ireland, United Kingdom, Germany, and Austria. The objects are selected as exhibiting the characteristics of “heavily edited” objects. We consider “heavily edited” objects as having 15 or more versions over the object's lifetime. Our results indicate that there are some serious issues arising from the way contributors tag or annotate objects in OSM. Values assigned to the “name” and “highway” attributes are often subject to frequent and unexpected change. However, this “tag flip‐flopping” is not found to be strongly correlated with increasing numbers of contributors. We also show problems with usage of the OSM ontology/controlled vocabularly. The majority of errors occurring were caused by contributors choosing values from the ontology “by hand” and spelling these values incorrectly. These issues could have a potentially detrimental effect on the quality of OSM data while at the same time damaging the perception of OSM in the GIS community. The current state of tagging and annotation in OSM is not perfect. We feel that the problems identified are a combination of the flexibility of the tagging process in OSM and the lack of a strict mechanism for checking adherence to the OSM ontology for specific core attributes. More studies related to comparing the names of features in OSM to recognized ground‐truth datasets are required. 相似文献
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Automated Digital Photogrammetry: A Valuable Tool for Small‐scale Geomorphological Research for the Non‐photogrammetrist? 总被引：1，自引：0，他引：1
Bruce Lascelles David Favis-Mortlock Tony Parsons & John Boardman 《Transactions in GIS》2002,6(1):5-15
Digital photogrammetry provides a tool with which to automatically generate digital elevation models (DEMs). The necessary equipment is now both readily available and affordable: thus there is considerable potential for this technique to be widely adopted in geomorphological studies. But is it possible for geomorphologists without a background in photogrammety to use it successfully? As part of a larger study into rill initiation by overland flow, a non‐metric digital camera and ERDAS IMAGINE OrthoMAX software were used to generate small‐scale DEMs of soil surface microtopography. This paper reports on the procedure used, highlights potential pitfalls, and comments on the quality of the resultant DEMs. Whilst acquisition of high‐quality images using a digital camera is relatively straightforward, problems were subsequently encountered due to the small size of the internal imager and the need for camera calibration. Potential stumbling blocks in the use of the software lay in the setting‐up of ground control points and the use of tie‐points and check‐points, as well as several software glitches not identified in the current manual. Nonetheless, once these problems were overcome the technique proved to be a simple, effective and fast tool for generating high quality microtopographical DEMs. This methodology shows great promise for future geomorphological studies that require these kinds of surface data. 相似文献
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Proximity is a fundamental concept in any comprehensive ontology of space ( Worboys 2001 ). The provision of a context‐contingent translation mechanism between linguistic proximity measures (e.g. “near”, “far”) and metric distance measures is an important topic in current GIS research. After a discussion of context factors that mediate the relationship between linguistic and metric distance measures, we present a statistical approach, Ordered Logit Regression, to the context‐contingent proximity modeling. The approach can predict proximity given the corresponding metric distance and context variables. An empirical case study with human subjects is carried out using this statistical approach. Interpretation and predictive accuracy of the empirical case study are discussed. 相似文献
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OpenStreetMap (OSM) is a very well known and popular Volunteered Geographic Information (VGI) project on the Internet. In January 2013 OSM gained its one millionth registered member. Several studies have shown that only a small percentage of these registered members carry out the large majority of the mapping and map editing work. In this article we discuss results from a social‐network based analysis of seven major cities in OSM in an effort to understand if there is quantitative evidence of interaction and collaboration between OSM members in these areas. Are OSM contributors working on their own to build OSM databases in these cities or is there evidence of collaboration between OSM contributors? We find that in many cases high frequent contributors (“senior mappers”) perform very large amounts of mapping work on their own but do interact (edit/update) contributions from lower frequency contributors. 相似文献
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Qualitative locations describe spatial objects by relating the spatial objects to a frame of reference (e.g. a regional partition in this study) with qualitative relations. Existing models only formalize spatial objects, frames of reference, and their relations at one scale, thus limiting their applicability in representing location changes of spatial objects across scales. A topology‐based, multi‐scale qualitative location model is proposed to represent the associations of multiple representations of the same objects with respect to the frames of reference at different levels. Multi‐scale regional partitions are first presented to be the frames of reference at multiple levels of scale. Multi‐scale locations are then formalized to relate multiple representations of the same objects to the multiple frames of reference by topological relations. Since spatial objects, frames of reference, and topological relations in qualitative locations are scale dependent, scale transformation approaches are presented to derive possible coarse locations from detailed locations by incorporating polygon merging, polygon‐to‐line and polygon‐to‐point operators. 相似文献
15.
Estimates of solar radiation distribution in urban areas are often limited by the complexity of urban environments. These limitations arise from spatial structures such as buildings and trees that affect spatial and temporal distributions of solar fluxes over urban surfaces. The traditional solar radiation models implemented in GIS can address this problem only partially. They can be adequately used only for 2‐D surfaces such as terrain and rooftops. However, vertical surfaces, such as facades, require a 3‐D approach. This study presents a new 3‐D solar radiation model for urban areas represented by 3‐D city models. The v.sun module implemented in GRASS GIS is based on the existing solar radiation methodology used in the topographic r.sun model with a new capability to process 3‐D vector data representing complex urban environments. The calculation procedure is based on the combined vector‐voxel approach segmenting the 3‐D vector objects to smaller polygon elements according to a voxel data structure of the volume region. The shadowing effects of surrounding objects are considered using a unique shadowing algorithm. The proposed model has been applied to the sample urban area with results showing strong spatial and temporal variations of solar radiation flows over complex urban surfaces. 相似文献
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Enriching the GIScience research agenda: Fusing augmented reality and location‐based social networks 下载免费PDF全文
下载免费PDF全文 Augmented reality (AR) overlays real‐world views or scenes with virtual, computer‐generated objects that appear to visually coexist in the same space. Location‐based social networks (LBSNs) are platforms for individuals to be connected through the interdependency derived from their physical locations and their location‐tagged social media content. Current research and development in both areas focuses on integrating mobile‐based AR and LBSNs. Several applications (e.g., Sekai Camera and Wallame) have been developed and commercialized successfully. However, little research has been done on the potential impacts and successful evaluation methods of AR‐integrated LBSNs in the GIScience field. To close this gap, the article outlines the impacts and benefits of AR‐integrated LBSNs and highlights the importance of LBSNs in GIScience research. Based on the status quo of AR‐integrated LBSNs, this article discusses—from theoretical and application‐oriented perspectives—how AR‐integrated LBSNs could enrich the GIScience research agenda in three aspects: data conflation, platial GIS, and multimedia storytelling. The article concludes with guidelines on visualization, functionality, and ethics that aim to help users develop and evaluate AR‐integrated LBSNs. 相似文献
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Field Techniques in Remote Sensing: Learning by Doing 总被引：1，自引：0，他引：1
Donald C. Rundquist 《国际地球制图》2013,28(1):85-90
Abstract The paper summarizes one professor's observations and resulting approach to teaching a semester‐long course on the subject of field techniques as they relate to remote‐sensing campaigns. The text describes how a “learning‐by‐doing strategy” is applied to such a course. More specifically, the paper describes how the instructor requires students to design, construct, and actually implement “hardware solutions” to problems involving collection of spectral (and ancillary) data in the field. Pupils must test their developed methodologies and “technological creations” with regard to a focused research problem undertaken in a difficult field setting during a week‐long outdoor experience. The students are expected to evaluate, and possibly modify, their methods and procedures “on‐the‐fly.” Individual group research problems, methods, and hardware solutions are briefly described, and selected student evaluations of the experience are provided. 相似文献
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This article studies the analysis of moving object data collected by location‐aware devices, such as GPS, using graph databases. Such raw trajectories can be transformed into so‐called semantic trajectories, which are sequences of stops that occur at “places of interest.” Trajectory data analysis can be enriched if spatial and non‐spatial contextual data associated with the moving objects are taken into account, and aggregation of trajectory data can reveal hidden patterns within such data. When trajectory data are stored in relational databases, there is an “impedance mismatch” between the representation and storage models. Graphs in which the nodes and edges are annotated with properties are gaining increasing interest to model a variety of networks. Therefore, this article proposes the use of graph databases (Neo4j in this case) to represent and store trajectory data, which can thus be analyzed at different aggregation levels using graph query languages (Cypher, for Neo4j). Through a real‐world public data case study, the article shows that trajectory queries are expressed more naturally on the graph‐based representation than over the relational alternative, and perform better in many typical cases. 相似文献
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Land use and marine spatial planning processes are increasingly supported by systematic assessment techniques, particularly by multi‐criteria spatial analysis methods. This has been facilitated by the growing release and uptake of web‐mapping tools, which contribute to transparent, consistent, and informed planning processes and decisions. This article reviews the usability, functionality, and applicability of contemporary planning web‐mapping tools to identify the state‐of‐the‐art and future prospects. The review reveals that interfaces are increasingly available and intuitively applicable by non‐specialized users. Basic map navigation and data querying functionality is being expanded to incorporate advanced map‐making and online data geoprocessing capabilities that enable deriving new data and insights. However, the majority of published planning web tools are one‐off solutions, and a disconnect between research and practice is rendering many of these inaccessible or obsolete. Despite the significant progress made in advancing their provision in the last decade, there is a need for developing transferable interfaces that are maintained beyond project end dates, for them to effectively and consistently support planning processes. 相似文献
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Data contributed by a large number of non‐experts is increasingly used to validate and curate land cover data, with location‐based games (LBGs) developed for this purpose generating particular interest. We here present our findings on StarBorn, a novel LBG with a strong focus on game play. Users conquer game‐tiles by visiting real‐world locations and collecting land cover data. Within three months, StarBorn generated 13,319 land cover classifications by 84 users. Results show that data are concentrated around users’ daily life spaces, agreement among users is highest for urban and industry land cover, and user‐generated land cover classifications exhibit high agreement with an authoritative data set. However, we also observe low user retention rates and negative correlations between number of contributions and agreement rates with an authoritative land cover product. We recommend that future work consider not only game play, but also how motivational aspects influence behavior and data quality. We conclude that LBGs are suitable tools for generating cost‐efficient in‐situ land cover classifications. 相似文献