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Ling Bian 《Transactions in GIS》2013,17(1):1-17
The dispersion of communicable diseases in a population is intrinsically spatial. In the last several decades, a range of spatial approaches has been devised to model epidemiological processes; and they differ significantly from each other. A review of spatially oriented epidemiological models is necessary to assess advances in spatial approaches to modeling disease dispersion and to help identify those most appropriate for specific research goals. The most notable difference in the design of these spatially oriented models is the scale and mobility of the modeling unit. Using two criteria, this review identifies six types of spatially oriented models. These include: (1) population‐based wave models, (2) sub‐population models, (3) individual‐based cellular automata models, (4) mobile sub‐population models, (5) individual‐based spatially implicit models, and (6) individual‐based mobile models. Each model type is evaluated in terms of its design principles, assumptions, and intended applications. For the evaluation of design, four aspects of design principles are discussed: the modeling unit, the interaction between the modeling units, the spatial process, and the temporal process utilized in a design. Insights gained from this review can be useful for devising much‐needed spatially and temporally oriented strategies to forecast, prevent, and control communicable diseases. 相似文献
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Krzysztof Stereńczak Rafal Zapłata Maciej Sztampke Radomir Bałazy 《Transactions in GIS》2017,21(2):300-316
This article presents the results and potential of using volunteered geographic information (VGI) in heritage detection. Research was completed under the project entitled “Laser Discoverers – non‐invasive examination and documentation of archeological and historical objects in the ?wi?tokrzyskie Voivodeship”, carried out as a part of the Ministry of Science and Higher Education program entitled “The Paths of Copernicus”. Within the project, strong emphasis was placed on promotional and awareness‐raising activities, to involve as many voluntary users as possible. Project participants had at their disposal a web application, which provided access to a digital terrain model (DTM) where they identified possible heritage objects. All samples of data were additionally available in eight variants of sunshine, based on the simulation of sunlight from eight directions and at a constant angle. In total, 5,989 elementary areas with dimensions of 100 × 100 m were used for the project. After conducting a field inventory, Internet users together with specialists were able to recognize several thousands of potential archaeological and historic objects. During the project, approximately 10% of those features were verified through non‐invasive (field survey) work, with 75% success. 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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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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E.A. Addink J.G.P.W. Clevers S.M. de Jong G.F. Epema F.D. van der Meer A.K. Skidmore W.H. Bakker 《International Journal of Applied Earth Observation and Geoinformation》2006,8(4):237-245
Objective comparison of classification performance of earth observation images, acquired at different spatial resolutions (e.g. NOAA-AVHRR, IRS-MOS, IRS-WiFS, Landsat-TM, IRS-LISS), is complicated because both class definition and training site selection are hampered by the inherent scale differences. This paper presents a new, generic method to compare the information content of such a set of images, the “Stained Glass Procedure”. It overcomes the stated problems by computing the scale-dependent, internal spectral variation in an image and by using this as an indicator for land cover information. The Stained Glass Procedure creates segments in the images and calculates the internal spectral variation in a high-spatial-resolution image for each segment. For each image from the set the average variance, weighted to area, is calculated. The Stained Glass Procedure can be used to predict the performance of sensors that are not available, yet, or to roughly determine the optimal spatial resolution for the classification of a specific area.The procedure was applied to images with pixel sizes ranging from 23 to 1100 m. Classification detail of Envisat-MERIS (300 m pixel size), not included in the image set, could be predicted accurately using the Stained Glass Procedure.The Stained Glass Procedure applies one procedure to all images, without any subjective decision during the analysis, thus offering a method to compare images with different pixel sizes in terms of classification detail that is truly objective. 相似文献
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Application of the Fisher's “Horizon Viewshed” to a proposed power transmission line in Nozzano (Italy) 
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下载免费PDF全文 Federico Fontani 《Transactions in GIS》2017,21(4):835-843
Visibility algorithms have progressed very little since early GIS software, and today the typical approach is still based on the simple binary logic (visible – not visible). Specialized packages, such as Esri's 3DAnalyst, provide tools able only to identify the cells from which an observer can see the evaluated target object. This technical note presents an experimental approach to combining different Esri tools into a model in order to return the visibility analysis based on the Fisher's “horizon viewshed” approach (Fisher, 1996 ). The latter consists in evaluating whether an object in the landscape rises above the skyline or remains below it. The model has been applied to study the visual impact of an High Voltage Power line in the area of Nozzano Castle, Lucca (Italy). 相似文献
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C. Brunsdon 《Transactions in GIS》2001,5(1):1-3
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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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Ecological research within the US Environmental Protection Agency's Office of Research and Development has recently changed its focus to quantifying and mapping ecosystem services provided to humans. Our local research group has been charged to develop a regional assessment of several ecosystem services in the Albemarle‐Pamlico Estuary System (APES). Time, data, and funding constraints precluded explicit modeling of the entire APES, so in Phase 1 of our research plan we chose to model ecosystem services in a random sample of headwater catchments. After observing numerous inconsistencies between the National Hydrography Dataset‐Plus (NHDPlus) stream network and the Virginia/North Carolina Watershed Boundary Dataset 12‐digit HUC coverage, we began by creating modified 12‐digit hydrologic units (HUCs) by aggregating smaller catchments delineated within the NHDPlus. In defining our population of interest (headwater 12‐digit HUCs with perennial, natural, wadeable pour points), we generally excluded HUCs that had multiple pour points, no pour points, or whose pour points were intermittent streams, artificial segments, ditches/canals, or lentic systems (lakes and reservoirs). After taking these actions, 318 HUCs remained and a stratified random sample (Omnerik ecoregions as strata) of 50 HUCs was chosen from this population. 相似文献
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Vania Bogorny Chiara Renso Artur Ribeiro de Aquino Fernando de Lucca Siqueira Luis Otavio Alvares 《Transactions in GIS》2014,18(1):66-88
Several works have been proposed in the last few years for raw trajectory data analysis, and some attempts have been made to define trajectories from a more semantic point of view. Semantic trajectory data analysis has received significant attention recently, but the formal definition of semantic trajectory, the set of aspects that should be considered to semantically enrich trajectories and a conceptual data model integrating these aspects from a broad sense is still missing. This article presents a semantic trajectory conceptual data model named CONSTAnT, which defines the most important aspects of semantic trajectories. We believe that this model will be the foundation for the design of semantic trajectory databases, where several aspects that make a trajectory “semantic” are taken into account. The proposed model includes the concepts of semantic subtrajectory, semantic points, geographical places, events, goals, environment and behavior, to create a general concept of semantic trajectory. The proposed model is the result of several years of work by the authors in an effort to add more semantics to raw trajectory data for real applications. Two application examples and different queries show the flexibility of the model for different domains. 相似文献
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Close range photogrammetry projects rely upon a clear and unambiguous specification of end-user requirements to inform decisions relating to the format, coverage, accuracy and complexity of the final deliverable. Invariably such deliverables will be a partial and incomplete abstraction of the real world where the benefits of higher accuracy and increased complexity must be traded against the cost of the project. As photogrammetric technologies move into the digital era, computerisation offers opportunities for the photogrammetrist to revisit established mapping traditions in order to explore new markets. One such market is that for three-dimensional Virtual Reality (VR) models for clients who have previously had little exposure to the capabilities, and limitations, of photogrammetry and may have radically different views on the cost/benefit trade-offs in producing geometric models. This paper will present some examples of the authors' recent experience of such markets, drawn from a number of research and commercial projects directed towards the modelling of complex man-made objects. This experience seems to indicate that suitably configured digital image archives may form an important deliverable for a wide range of photogrammetric projects and supplement, or even replace, more traditional CAD models. 相似文献
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Grace Nangendo Andrew K. Skidmore Henk van Oosten 《ISPRS Journal of Photogrammetry and Remote Sensing》2007,61(6):393-404
In mapping the forest–woodland–savannah mosaic of Budongo Forest Reserve, Uganda, four classification methods were compared, i.e. Maximum Likelihood classifier (MLC), Spectral Angle Mapper (SAM), Maximum Likelihood combined with an Expert System (MaxExpert) and Spectral Angle Mapper combined with an Expert System (SAMExpert). The combination of conventional classifiers with an Expert System proved to be an effective approach for forest mapping. This was also the first time that the SAMExpert had been used in the mapping of tropical forests. SAMExpert not only maps with high accuracy, but is also fast and easy to use, making it attractive for use in less developed countries. Another advantage is that it can be executed on a standard PC set up for image processing.Combining the conventional classifiers (MLC and SAM) with the Expert System significantly improved the classification accuracy. The highest overall accuracy (94.6%) was obtained with SAMExpert. The MaxExpert approach yielded a map with an accuracy of 85.2%, which was also significantly higher than that obtained using the conventional MLC approach.The SAMExpert classifier accurately mapped individual classes. Of the four classes of woodland mapped, the Open Woodland (with Terminalia) and Wooded Grassland classes were more accurately mapped using SAMExpert. The Open Woodland had been previously identified by ecologists, but had never been mapped. 相似文献