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ISPRS Int. J. Geo-Inf., Volume 2, Issue 3 (September 2013) – 17 articles , Pages 553-907

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409 KiB  
Article
The Semantics of Web Services: An Examination in GIScience Applications
by Xuan Shi
ISPRS Int. J. Geo-Inf. 2013, 2(3), 888-907; https://doi.org/10.3390/ijgi2030888 - 23 Sep 2013
Cited by 9 | Viewed by 5928
Abstract
Web service is a technological solution for software interoperability that supports the seamless integration of diverse applications. In the vision of web service architecture, web services are described by the Web Service Description Language (WSDL), discovered through Universal Description, Discovery and Integration (UDDI) [...] Read more.
Web service is a technological solution for software interoperability that supports the seamless integration of diverse applications. In the vision of web service architecture, web services are described by the Web Service Description Language (WSDL), discovered through Universal Description, Discovery and Integration (UDDI) and communicate by the Simple Object Access Protocol (SOAP). Such a divination has never been fully accomplished yet. Although it was criticized that WSDL only has a syntactic definition of web services, but was not semantic, prior initiatives in semantic web services did not establish a correct methodology to resolve the problem. This paper examines the distinction and relationship between the syntactic and semantic definitions for web services that characterize different purposes in service computation. Further, this paper proposes that the semantics of web service are neutral and independent from the service interface definition, data types and platform. Such a conclusion can be a universal law in software engineering and service computing. Several use cases in the GIScience application are examined in this paper, while the formalization of geospatial services needs to be constructed by the GIScience community towards a comprehensive ontology of the conceptual definitions and relationships for geospatial computation. Advancements in semantic web services research will happen in domain science applications. Full article
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637 KiB  
Article
A Suite of Tools for ROC Analysis of Spatial Models
by Jean-François Mas, Britaldo Soares Filho, Robert Gilmore Pontius, Michelle Farfán Gutiérrez and Hermann Rodrigues
ISPRS Int. J. Geo-Inf. 2013, 2(3), 869-887; https://doi.org/10.3390/ijgi2030869 - 10 Sep 2013
Cited by 102 | Viewed by 16100
Abstract
The Receiver Operating Characteristic (ROC) is widely used for assessing the performance of classification algorithms. In GIScience, ROC has been applied to assess models aimed at predicting events, such as land use/cover change (LUCC), species distribution and disease risk. However, GIS software packages [...] Read more.
The Receiver Operating Characteristic (ROC) is widely used for assessing the performance of classification algorithms. In GIScience, ROC has been applied to assess models aimed at predicting events, such as land use/cover change (LUCC), species distribution and disease risk. However, GIS software packages offer few statistical tests and guidance tools for ROC analysis and interpretation. This paper presents a suite of GIS tools designed to facilitate ROC curve analysis for GIS users by applying proper statistical tests and analysis procedures. The tools are freely available as models and submodels of Dinamica EGO freeware. The tools give the ROC curve, the area under the curve (AUC), partial AUC, lower and upper AUCs, the confidence interval of AUC, the density of event in probability bins and tests to evaluate the difference between the AUCs of two models. We present first the procedures and statistical tests implemented in Dinamica EGO, then the application of the tools to assess LUCC and species distribution models. Finally, we interpret and discuss the ROC-related statistics resulting from various case studies. Full article
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672 KiB  
Article
An Improved Neural Network Training Algorithm for Wi-Fi Fingerprinting Positioning
by Esmond Mok and Bernard K.S. Cheung
ISPRS Int. J. Geo-Inf. 2013, 2(3), 854-868; https://doi.org/10.3390/ijgi2030854 - 03 Sep 2013
Cited by 29 | Viewed by 7729
Abstract
Ubiquitous positioning provides continuous positional information in both indoor and outdoor environments for a wide spectrum of location based service (LBS) applications. With the rapid development of the low-cost and high speed data communication, Wi-Fi networks in many metropolitan cities, strength of signals [...] Read more.
Ubiquitous positioning provides continuous positional information in both indoor and outdoor environments for a wide spectrum of location based service (LBS) applications. With the rapid development of the low-cost and high speed data communication, Wi-Fi networks in many metropolitan cities, strength of signals propagated from the Wi-Fi access points (APs) namely received signal strength (RSS) have been cleverly adopted for indoor positioning. In this paper, a Wi-Fi positioning algorithm based on neural network modeling of Wi-Fi signal patterns is proposed. This algorithm is based on the correlation between the initial parameter setting for neural network training and output of the mean square error to obtain better modeling of the nonlinear highly complex Wi-Fi signal power propagation surface. The test results show that this neural network based data processing algorithm can significantly improve the neural network training surface to achieve the highest possible accuracy of the Wi-Fi fingerprinting positioning method. Full article
(This article belongs to the Special Issue Indoor Positioning and Indoor Navigation)
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745 KiB  
Article
Spatio-Temporal Data Construction
by Hai Ha Le
ISPRS Int. J. Geo-Inf. 2013, 2(3), 837-853; https://doi.org/10.3390/ijgi2030837 - 27 Aug 2013
Cited by 3 | Viewed by 5508
Abstract
On the route to a spatio-temporal geoscience information system, an appropriate data model for geo-objects in space and time has been developed. In this model, geo-objects are represented as sequences of geometries and properties with continuous evolution in each time interval. Because geomodeling [...] Read more.
On the route to a spatio-temporal geoscience information system, an appropriate data model for geo-objects in space and time has been developed. In this model, geo-objects are represented as sequences of geometries and properties with continuous evolution in each time interval. Because geomodeling software systems usually model objects at specific time instances, we want to interpolate the geometry and properties from two models of an object with only geometrical constraints (no physical or mechanical constraints). This process is called spatio-temporal data construction or morphological interpolation of intermediate geometries. This paper is strictly related to shape morphing, shape deformation, cross-parameterization and compatible remeshing and is only concerned with geological surfaces. In this study, two main sub-solutions construct compatible meshes and find trajectories in which vertices of the mesh evolve. This research aims to find an algorithm to construct spatio-temporal data with some constraints from the geosciences, such as cutting surfaces by faulting or fracturing phenomena and evolving boundaries attached to other surfaces. Another goal of this research is the implementation of the algorithm in a software product, namely a gOcad plug-in. The four main procedures of the algorithm are cutting the surfaces, setting up constraints, partitioning and calculating the parameterizations and trajectories. The software has been tested to construct data for a salt dome and other surfaces in regard to the geological processes of faulting, deposition and erosion. The result of this research is an algorithm and software for the construction of spatio-temporal data. Full article
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1519 KiB  
Article
Visual Analysis for Nowcasting of Multidimensional Lightning Data
by Stefan Peters and Liqiu Meng
ISPRS Int. J. Geo-Inf. 2013, 2(3), 817-836; https://doi.org/10.3390/ijgi2030817 - 26 Aug 2013
Cited by 9 | Viewed by 8569
Abstract
Globally, most weather-related damages are caused by thunderstorms. Besides floods, strong wind, and hail, one of the major thunderstorm ground effects is lightning. Therefore, lightning investigations, including detection, cluster identification, tracking, and nowcasting are essential. To enable reliable decisions, current and predicted lightning [...] Read more.
Globally, most weather-related damages are caused by thunderstorms. Besides floods, strong wind, and hail, one of the major thunderstorm ground effects is lightning. Therefore, lightning investigations, including detection, cluster identification, tracking, and nowcasting are essential. To enable reliable decisions, current and predicted lightning cluster- and track features as well as analysis results have to be represented in the most appropriate way. Our paper introduces a framework which includes identification, tracking, nowcasting, and in particular visualization and statistical analysis of dynamic lightning data in three-dimensional space. The paper is specifically focused on enabling users to conduct the visual analysis of lightning data for the purpose of identification and interpretation of spatial-temporal patterns embedded in lightning data, and their dynamics. A graphic user interface (GUI) is developed, wherein lightning tracks and predicted lightning clusters, including their prediction certainty, can be investigated within a 3D view or within a Space-Time-Cube. In contrast to previous work, our approach provides insight into the dynamics of past and predicted 3D lightning clusters and cluster features over time. We conclude that an interactive visual exploration in combination with a statistical analysis can provide new knowledge within lightning investigations and, thus, support decision-making in weather forecast or lightning damage prevention. Full article
(This article belongs to the Special Issue Geovisualization and Analysis of Dynamic Phenomena)
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1298 KiB  
Article
A Comparison of Precise Leveling and Persistent Scatterer SAR Interferometry for Building Subsidence Rate Measurement
by Kirsi Karila, Mika Karjalainen, Juha Hyyppä, Jarkko Koskinen, Veikko Saaranen and Paavo Rouhiainen
ISPRS Int. J. Geo-Inf. 2013, 2(3), 797-816; https://doi.org/10.3390/ijgi2030797 - 21 Aug 2013
Cited by 26 | Viewed by 8482
Abstract
It is well known that the most accurate method to detect changes of height is the geodetic precise leveling method. Due to the high demand work and time needed for precise leveling alternative methods are studied to obtain high quality height information. Differential [...] Read more.
It is well known that the most accurate method to detect changes of height is the geodetic precise leveling method. Due to the high demand work and time needed for precise leveling alternative methods are studied to obtain high quality height information. Differential SAR interferometry techniques such as the Persistent Scatterer Interferometry (PSI) method are studied to detect millimeter level deformations in urban areas. Additionally, SAR analysis will provide spatially extensive information on subsidence. On the other hand, PSI subsidence rates have not yet been comprehensively compared to the precise leveling measurements of the subsidence of individual buildings. Typically subsidence rates are interpolated to a continuous spatial surface, but in this study, spatially discontinuous subsidence was measured for a set of individual buildings. Therefore, we conducted three precise leveling campaigns and measured in total 82 geodetic-grade bolts, which were tightly attached to the building foundations. Moreover, we used additional leveling data (obtained from the local authorities), which contained long time series of leveling data for individual buildings. In the present study, ERS and ENVISAT satellite SAR data were processed using a PSI algorithm and the results were compared to leveling data of individual buildings. Full article
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724 KiB  
Article
Semantic Interoperability of Sensor Data with Volunteered Geographic Information: A Unified Model
by Mohamed Bakillah, Steve H.L. Liang, Alexander Zipf and Jamal Jokar Arsanjani
ISPRS Int. J. Geo-Inf. 2013, 2(3), 766-796; https://doi.org/10.3390/ijgi2030766 - 12 Aug 2013
Cited by 16 | Viewed by 10971
Abstract
The increasing availability of sensor devices has resulted in important volumes of sensor data, which has raised the issue of making these data fully discoverable and interpretable by applications and end-users. The idea of OGC Sensor Web Enablement (SWE) has addressed this issue [...] Read more.
The increasing availability of sensor devices has resulted in important volumes of sensor data, which has raised the issue of making these data fully discoverable and interpretable by applications and end-users. The idea of OGC Sensor Web Enablement (SWE) has addressed this issue by proposing a set of standards to enable accessibility of sensor data over the Web. Similarly, there is a growing interest in volunteered geographic information (VGI). Considering that several researchers have highlighted the potential of this new type of information as a complement to existing, “traditional” data, it becomes important to develop frameworks to support the integration of VGI from several sources and with other types of data. In this paper, we make a first step in this direction by proposing a framework for the semantic interoperability of sensor data and VGI. After having performed an investigation of the types of VGI applications, we have developed a conceptual model of VGI aligned with relevant ISO standards for describing geospatial features. The purpose of this model is to support the generation of common descriptions for VGI applications, which will act as interfaces to higher-level services, such as discovery and reasoning services, in order to be exploited in conjunction with sensor data by client applications. This process is described through architecture for semantic interoperability of sensor data and VGI that we have developed and that we intend to use to set guidelines for future research on integration of VGI in sensor data cyberinfrastructures. We illustrate the possibilities created by the proposed framework with a description of the various services and interfaces required to implement the framework. Full article
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416 KiB  
Review
Geospatial Cyberinfrastructure and Geoprocessing Web—A Review of Commonalities and Differences of E-Science Approaches
by Barbara Hofer
ISPRS Int. J. Geo-Inf. 2013, 2(3), 749-765; https://doi.org/10.3390/ijgi2030749 - 09 Aug 2013
Cited by 7 | Viewed by 6762
Abstract
Online geoprocessing gains momentum through increased online data repositories, web service infrastructures, online modeling capabilities and the required online computational resources. Advantages of online geoprocessing include reuse of data and services, extended collaboration possibilities among scientists, and efficiency thanks to distributed computing facilities. [...] Read more.
Online geoprocessing gains momentum through increased online data repositories, web service infrastructures, online modeling capabilities and the required online computational resources. Advantages of online geoprocessing include reuse of data and services, extended collaboration possibilities among scientists, and efficiency thanks to distributed computing facilities. In the field of Geographic Information Science (GIScience), two recent approaches exist that have the goal of supporting science in online environments: the geospatial cyberinfrastructure and the geoprocessing web. Due to its historical development, the geospatial cyberinfrastructure has strengths related to the technologies required for data storage and processing. The geoprocessing web focuses on providing components for model development and sharing. These components shall allow expert users to develop, execute and document geoprocessing workflows in online environments. Despite this difference in the emphasis of the two approaches, the objectives, concepts and technologies they use overlap. This paper provides a review of the definitions and representative implementations of the two approaches. The provided overview clarifies which aspects of e-Science are highlighted in approaches differentiated in the geographic information domain. The discussion of the two approaches leads to the conclusion that synergies in research on e-Science environments shall be extended. Full-fledged e-Science environments will require the integration of approaches with different strengths. Full article
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1705 KiB  
Article
HCTNav: A Path Planning Algorithm for Low-Cost Autonomous Robot Navigation in Indoor Environments
by Marco Pala, Nafiseh Osati Eraghi, Fernando López-Colino, Alberto Sanchez, Angel De Castro and Javier Garrido
ISPRS Int. J. Geo-Inf. 2013, 2(3), 729-748; https://doi.org/10.3390/ijgi2030729 - 09 Aug 2013
Cited by 19 | Viewed by 9186
Abstract
Low-cost robots are characterized by low computational resources and limited energy supply. Path planning algorithms aim to find the optimal path between two points so the robot consumes as little energy as possible. However, these algorithms were not developed considering computational limitations ( [...] Read more.
Low-cost robots are characterized by low computational resources and limited energy supply. Path planning algorithms aim to find the optimal path between two points so the robot consumes as little energy as possible. However, these algorithms were not developed considering computational limitations (i.e., processing and memory capacity). This paper presents the HCTNav path-planning algorithm (HCTLab research group’s navigation algorithm). This algorithm was designed to be run in low-cost robots for indoor navigation. The results of the comparison between HCTNav and the Dijkstra’s algorithms show that HCTNav’s memory peak is nine times lower than Dijkstra’s in maps with more than 150,000 cells. Full article
(This article belongs to the Special Issue Indoor Positioning and Indoor Navigation)
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2068 KiB  
Article
Towards an Authoritative OpenStreetMap: Conflating OSM and OS OpenData National Maps’ Road Network
by Amir Pourabdollah, Jeremy Morley, Steven Feldman and Mike Jackson
ISPRS Int. J. Geo-Inf. 2013, 2(3), 704-728; https://doi.org/10.3390/ijgi2030704 - 05 Aug 2013
Cited by 28 | Viewed by 11212
Abstract
The quality aspects of OpenStreetMap (OSM), as the global representation of crowd-sourced mapping, have always been of priomary concern to academics. While the methodologies for checking its quality against the national maps have been implemented by a number of studies, there are minimal [...] Read more.
The quality aspects of OpenStreetMap (OSM), as the global representation of crowd-sourced mapping, have always been of priomary concern to academics. While the methodologies for checking its quality against the national maps have been implemented by a number of studies, there are minimal works on how to practically improve the quality of OSM towards being an authoritative map source. This paper presents a method for conflating road attributes, namely the name and reference code, of OSM with the Open Data provided by Ordnance Survey (the British national mapping agency). The added values in the proposed methodology include the daily updates and serving of the conflated maps via open Web Services. More importantly, the OSM crowd correction is facilitated by frequently highlighting and web-serving the individual differences. There are currently over 5,800 differences in matching road names and references between the two datasets. In addition to describing the conflation methodology, the different geographic distribution patterns of the identified differences are discussed. A negative effect of the road density on the ratio of the mismatched features between the two datasets is observable, evidenced by their different geographical distribution over the map. It is shown that the best correspondence between attributes exists in the very dense areas, followed by the very low density areas, and lastly in the middle to large sized cities. Full article
(This article belongs to the Special Issue Collaborative Mapping)
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556 KiB  
Article
Alpine Glaciology: An Historical Collaboration between Volunteers and Scientists and the Challenge Presented by an Integrated Approach
by Laura Criscuolo, Monica Pepe, Roberto Seppi, Gloria Bordogna, Paola Carrara and Francesco Zucca
ISPRS Int. J. Geo-Inf. 2013, 2(3), 680-703; https://doi.org/10.3390/ijgi2030680 - 05 Aug 2013
Cited by 10 | Viewed by 9757
Abstract
European Alpine glaciology has a long tradition of studies and activities, in which researchers have often relied on the field work of some specialized volunteer operators. Despite the remarkable results of this cooperation, some problems in field data harmonization and in covering the [...] Read more.
European Alpine glaciology has a long tradition of studies and activities, in which researchers have often relied on the field work of some specialized volunteer operators. Despite the remarkable results of this cooperation, some problems in field data harmonization and in covering the whole range of monitored glaciers are still present. Moreover, dynamics of reduction, fragmentation and decline, which in recent decades characterize Alpine glaciers, make more urgent the need to improve spatial and temporal monitoring, still maintaining adequate quality standards. Scientific field monitoring activities on Alpine glaciers run parallel to a number of initiatives by individuals and amateur associations, keepers of alternative, experiential and para-scientific knowledge of the glacial environment. Problems of harmonization, coordination, recruitment and updating can be addressed with the help of a collaborative approach—citizen science-like—in which the scientific coordination guarantees information quality and web 2.0 tools operate as mediators between expert glaciologists and non-expert contributors. This paper gives an overview of glaciological information currently produced in the European Alpine region, representing it in an organized structure, functional to the discussion. An empowering solution is then proposed, both methodological and technological, for the integration of multisource data. Its characteristics, potentials and problems are discussed. Full article
(This article belongs to the Special Issue Collaborative Mapping)
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1098 KiB  
Article
Dynamics of Sheep Production in Brazil
by Potira Meirelles Hermuche, Rebecca Lima Albuquerque Maranhão, Renato Fontes Guimarães, Osmar Abílio De Carvalho, Júnior, Roberto Arnaldo Trancoso Gomes, Samuel Rezende Paiva and Concepta McManus
ISPRS Int. J. Geo-Inf. 2013, 2(3), 665-679; https://doi.org/10.3390/ijgi2030665 - 31 Jul 2013
Cited by 35 | Viewed by 10090
Abstract
Sheep production is present on all continents and has been practiced in Brazil since the colonization. In this study, the multitemporal dynamics of sheep production in Brazil is examined using official government data (Brazilian Institute for Geography and Statistics-IBGE) from 1976 to 2010. [...] Read more.
Sheep production is present on all continents and has been practiced in Brazil since the colonization. In this study, the multitemporal dynamics of sheep production in Brazil is examined using official government data (Brazilian Institute for Geography and Statistics-IBGE) from 1976 to 2010. Maps of flock growth rates and growth acceleration maps by municipality were elaborated. The Southern states are seen to show a reduction in production mainly due to the wool crisis in the 1970s and 80s. The Northeast is seen to be important for meat production. More recently, centerwest and northern states have shown an increase in growth rates but this is still incipient. The maps of growth, acceleration and midpoint for sheep production showed a noticeable return to an increase in production in the South in recent years. The midpoint of production flow was in the northeast direction, which has stagnated. There was great dynamics in sheep production over the whole Brazilian territory, which affected supply chains due to the expansion of domestic and foreign markets. Areas with higher fluctuations in production are more vulnerable in terms of investment policies. Full article
(This article belongs to the Special Issue Geovisualization and Analysis of Dynamic Phenomena)
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1170 KiB  
Article
Spatially-Explicit Simulation Modeling of Ecological Response to Climate Change: Methodological Considerations in Predicting Shifting Population Dynamics of Infectious Disease Vectors
by Radhika Dhingra, Violeta Jimenez, Howard H. Chang, Manoj Gambhir, Joshua S. Fu, Yang Liu and Justin V. Remais
ISPRS Int. J. Geo-Inf. 2013, 2(3), 645-664; https://doi.org/10.3390/ijgi2030645 - 22 Jul 2013
Cited by 6 | Viewed by 8961
Abstract
Poikilothermic disease vectors can respond to altered climates through spatial changes in both population size and phenology. Quantitative descriptors to characterize, analyze and visualize these dynamic responses are lacking, particularly across large spatial domains. In order to demonstrate the value of a spatially [...] Read more.
Poikilothermic disease vectors can respond to altered climates through spatial changes in both population size and phenology. Quantitative descriptors to characterize, analyze and visualize these dynamic responses are lacking, particularly across large spatial domains. In order to demonstrate the value of a spatially explicit, dynamic modeling approach, we assessed spatial changes in the population dynamics of Ixodes scapularis, the Lyme disease vector, using a temperature-forced population model simulated across a grid of 4 × 4 km cells covering the eastern United States, using both modeled (Weather Research and Forecasting (WRF) 3.2.1) baseline/current (2001–2004) and projected (Representative Concentration Pathway (RCP) 4.5 and RCP 8.5; 2057–2059) climate data. Ten dynamic population features (DPFs) were derived from simulated populations and analyzed spatially to characterize the regional population response to current and future climate across the domain. Each DPF under the current climate was assessed for its ability to discriminate observed Lyme disease risk and known vector presence/absence, using data from the US Centers for Disease Control and Prevention. Peak vector population and month of peak vector population were the DPFs that performed best as predictors of current Lyme disease risk. When examined under baseline and projected climate scenarios, the spatial and temporal distributions of DPFs shift and the seasonal cycle of key questing life stages is compressed under some scenarios. Our results demonstrate the utility of spatial characterization, analysis and visualization of dynamic population responses—including altered phenology—of disease vectors to altered climate. Full article
(This article belongs to the Special Issue Geovisualization and Analysis of Dynamic Phenomena)
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1024 KiB  
Article
Conflation Optimized by Least Squares to Maintain Geographic Shapes
by Guillaume Touya, Adeline Coupé, Jérémie Le Jollec, Olivier Dorie and Frank Fuchs
ISPRS Int. J. Geo-Inf. 2013, 2(3), 621-644; https://doi.org/10.3390/ijgi2030621 - 03 Jul 2013
Cited by 19 | Viewed by 9807
Abstract
Recent technologies allowed a major growth of geographical datasets with different levels of detail, different point of views, and different specifications, but on the same geographical extent. These datasets need to be integrated in order to benefit from their diversity. Conflation is one [...] Read more.
Recent technologies allowed a major growth of geographical datasets with different levels of detail, different point of views, and different specifications, but on the same geographical extent. These datasets need to be integrated in order to benefit from their diversity. Conflation is one of the solutions to provide integration. Conflation aims at combining data that represent same entities from several datasets, into a richer new dataset. This paper proposes a framework that provides a geometrical conflation that preserves the characteristic shapes of geographic data. The framework is based on least squares adjustment, inspired from least squares based generalization techniques. It does not require very precise pre-matching, which is interesting as automatic matching remains a challenging task. Several constraints are proposed to preserve different kind of shape and relations between features, while conflating data. The framework is applied to a real land use parcels conflation problem with excellent results. The least squares based conflation is evaluated, notably with comparisons with existing techniques like rubber sheeting. The paper also describes how the framework can be extended to other geometrical optimization problems. Full article
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943 KiB  
Article
Indoor Positioning for Smartphones Using Asynchronous Ultrasound Trilateration
by Viacheslav Filonenko, Charlie Cullen and James D. Carswell
ISPRS Int. J. Geo-Inf. 2013, 2(3), 598-620; https://doi.org/10.3390/ijgi2030598 - 27 Jun 2013
Cited by 60 | Viewed by 18604
Abstract
Modern smartphones are a great platform for Location Based Services (LBS). While outdoor LBS for smartphones has proven to be very successful, indoor LBS for smartphones has not yet fully developed due to the lack of an accurate positioning technology. In this paper [...] Read more.
Modern smartphones are a great platform for Location Based Services (LBS). While outdoor LBS for smartphones has proven to be very successful, indoor LBS for smartphones has not yet fully developed due to the lack of an accurate positioning technology. In this paper we present an accurate indoor positioning approach for commercial off-the-shelf (COTS) smartphones that uses the innate ability of mobile phones to produce ultrasound, combined with Time-Difference-of-Arrival (TDOA) asynchronous trilateration. We evaluate our indoor positioning approach by describing its strengths and weaknesses, and determine its absolute accuracy. This is accomplished through a range of experiments that involve variables such as position of control point microphones, position of phone within the room, direction speaker is facing and presence of user in the signal path. Test results show that our Lok8 (locate) mobile positioning system can achieve accuracies better than 10 cm in a real-world environment. Full article
(This article belongs to the Special Issue Indoor Positioning and Indoor Navigation)
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5144 KiB  
Article
Evaluation of Model Validation Techniques in Land Cover Dynamics
by Bayes Ahmed, Raquib Ahmed and Xuan Zhu
ISPRS Int. J. Geo-Inf. 2013, 2(3), 577-597; https://doi.org/10.3390/ijgi2030577 - 26 Jun 2013
Cited by 71 | Viewed by 9641
Abstract
This paper applies different methods of map comparison to quantify the characteristics of three different land change models. The land change models used for simulation are termed as “Stochastic Markov (St_Markov)”, “Cellular Automata Markov (CA_Markov)” and “Multi Layer Perceptron Markov (MLP_Markov)” models. Various [...] Read more.
This paper applies different methods of map comparison to quantify the characteristics of three different land change models. The land change models used for simulation are termed as “Stochastic Markov (St_Markov)”, “Cellular Automata Markov (CA_Markov)” and “Multi Layer Perceptron Markov (MLP_Markov)” models. Various model validation techniques such as per category method, kappa statistics, components of agreement and disagreement, three map comparison and fuzzy methods have then been applied. A comparative analysis of the validation techniques has also been discussed. In all cases, it is found that “MLP_Markov” gives the best results among the three modeling techniques. Fuzzy set theory is the method that seems best able to distinguish areas of minor spatial errors from major spatial errors. Based on the outcome of this paper, it is recommended that scientists should try to use the Kappa, three map comparison and fuzzy methods for model validation. This paper facilitates communication among land change modelers, because it illustrates the range of results for a variety of model validation techniques and articulates priorities for future research. Full article
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2975 KiB  
Article
Multi-Source Data Processing Middleware for Land Monitoring within a Web-Based Spatial Data Infrastructure for Siberia
by Jonas Eberle, Siegfried Clausnitzer, Christian Hüttich and Christiane Schmullius
ISPRS Int. J. Geo-Inf. 2013, 2(3), 553-576; https://doi.org/10.3390/ijgi2030553 - 26 Jun 2013
Cited by 15 | Viewed by 9827
Abstract
Land monitoring is a key issue in Earth system sciences to study environmental changes. To generate knowledge about change, e.g., to decrease uncertaincy in the results and build confidence in land change monitoring, multiple information sources are needed. Earth observation (EO) satellites and [...] Read more.
Land monitoring is a key issue in Earth system sciences to study environmental changes. To generate knowledge about change, e.g., to decrease uncertaincy in the results and build confidence in land change monitoring, multiple information sources are needed. Earth observation (EO) satellites and in situ measurements are available for operational monitoring of the land surface. As the availability of well-prepared geospatial time-series data for environmental research is limited, user-dependent processing steps with respect to the data source and formats pose additional challenges. In most cases, it is possible to support science with spatial data infrastructures (SDI) and services to provide such data in a processed format. A data processing middleware is proposed as a technical solution to improve interdisciplinary research using multi-source time-series data and standardized data acquisition, pre-processing, updating and analyses. This solution is being implemented within the Siberian Earth System Science Cluster (SIB-ESS-C), which combines various sources of EO data, climate data and analytical tools. The development of this SDI is based on the definition of automated and on-demand tools for data searching, ordering and processing, implemented along with standard-compliant web services. These tools, consisting of a user-friendly download, analysis and interpretation infrastructure, are available within SIB-ESS-C for operational use. Full article
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