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  • 1.
    Abugessaisa, Imad
    et al.
    Department of Medicine, Karolinska Institutet.
    Östman, Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Testing-SDI: E-government Prospective, Requirements, and Challenges2011In: International Journal of Public Information Systems, ISSN 1653-4360, Vol. 2011, no 1, p. 11-47Article in journal (Refereed)
    Abstract [en]

    Spatial Data Infrastructure denotes the collection of technologies, policies and institutional arrangements that facilitate the availability of and access to spatial information. During the last few years the development of spatial data infrastructure in Sweden has been influenced by two actions. The first was the European Directive in spatial data infrastructure namely Infrastructure for Spatial Information in Europe (INSPIRE), and the second action was the Swedish parliament's directive early in 2008 on e-Government. In a modern society, spatial data play major roles and have different applications such as information support during disaster prevention and management. These two milestones involving Geodata development have created huge demands and represent great challenges for researchers in the area of spatial data infrastructure. One of these challenges concerned the methodologies involved for testing proposed data specifications from INSPIRE. This paper addresses the above challenge and introduces a framework for testing Geodata. The testing of Geodata includes, the testing of the data specifications for different geographical themes and data structure, the performance testing of Opengeospatial Web Services (OWS) and the usability of Geoportals and services. The proposed methods were evaluated during a pilot test for a regional geoportal in Sweden, and the reported results in this paper show the feasibility and applicability of the methods used. The methods used assisted in the identification of the performance related defects and the bottleneck involved in relation to the response time, stress and load. The methods support the detection of different types of errors that occur during the testing time such as http error, timeout error, and socket error. During the pilot test of a geoportal, it was discovered that the response time was 30 seconds which is 6 times higher than the INSPIRE required time (Maximum 5 second), with 500 virtual users accessing the system and performing a specific task. A usability test was conducted which focused on the users' acceptance and the “think aloud” methods. The usability testing enabled the identification of user-interface related problems and the results were quantified to enable comparisons to be made with current results and those from the new test.

  • 2. Andrienko, Gennady
    et al.
    Dykes, JasonJiang, BinUniversity of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    GeoViz Hamburg 2011: Linking geovisualization with spatial analysis and modeling2011Collection (editor) (Refereed)
  • 3.
    Bagherbandi, Mohammad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Combination of seismic and an isostatic crustal thickness models using Butterworth filter in a spectral approach2012In: Journal of Asian Earth Sciences, ISSN 1367-9120, E-ISSN 1878-5786, Vol. 59, p. 240-248Article in journal (Refereed)
  • 4.
    Bagherbandi, Mohammad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Global earth isostatic model using smoothed Airy-Heiskanenand Vening Meinesz hypotheses2012In: Earth Science Informatics, ISSN 1865-0473, Vol. 5, no 2, p. 93-104Article in journal (Refereed)
  • 5.
    Bagherbandi, Mohammad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Impact of compensating mass on the topographic mass: A study using isostatic and non-isostatic Earth crustal models2012In: Acta Geodaetica et Geophysica Hungarica, ISSN 1217-8977, E-ISSN 1587-1037, Vol. 47, no 1, p. 29-51Article in journal (Refereed)
  • 6.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Eshagh, Mehdi
    Royal Institute of Technology (KTH), Stockholm, Sweden, and K.N.Toosi University of Technology, Tehran, Iran .
    Crustal thickness recovery using an isostatic model and GOCE data2012In: Earth Planets and Space, ISSN 1343-8832, E-ISSN 1880-5981, Vol. 64, no 11, p. 1053-1057Article in journal (Refereed)
    Abstract [en]

    One of the GOCE satellite mission goals is to study the Earth's interior structure including its crustal thickness. A gravimetric-isostatic Moho model, based on the Vening Meinesz-Moritz (VMM) theory and GOCE gradiometric data, is determined beneath Iran's continental shelf and surrounding seas. The terrestrial gravimetric data of Iran are also used in a nonlinear inversion for a recovering-Moho model applying the VMM model. The newly-computed Moho models are compared with the Moho data taken from CRUST2.0. The root-mean-square (RMS) of differences between the CRUST2.0 Moho model and the recovered model from GOCE and that from the terrestrial gravimetric data are 3.8 km and 4.6 km, respectively.

  • 7.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Eshagh, Mehdi
    Islamic Azad Univ, Dept Surveying.
    Recovery of Moho’s undulations based on the Vening Meinesz–Moritz theory from satellite gravity gradiometry data: A simulation study2012In: Advances in Space Research, ISSN 0273-1177, E-ISSN 1879-1948, Vol. 49, no 6, p. 1097-1111Article in journal (Refereed)
  • 8.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute. Division of Geodesy and Geoinformatics, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Sjöberg, Lars E.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    A synthetic Earth gravity model based on a topographic-isostatic model2012In: Studia Geophysica et Geodaetica, ISSN 0039-3169, E-ISSN 1573-1626, Vol. 56, no 4, p. 935-955Article in journal (Refereed)
    Abstract [en]

    The Earth's gravity field is related to the topographic potential in medium and higher degrees, which is isostatically compensated. Hence, the topographic-isostatic (TI) data are indispensable for extending an available Earth Gravitational Model (EGM) to higher degrees. Here we use TI harmonic coefficients to construct a Synthetic Earth Gravitational Model (SEGM) to extend the EGMs to higher degrees. To achieve a high-quality SEGM, a global geopotential model (EGM96) is used to describe the low degrees, whereas the medium and high degrees are obtained from the TI or topographic potential. This study differes from others in that it uses a new gravimetric-isostatic model for determining the TI potential. We test different alternatives based on TI or only topographic data to determine the SEGM. Although the topography is isostatically compensated only to about degree 40-60, our study shows that using a compensation model improves the SEGM in comparison with using only topographic data for higher degree harmonics. This is because the TI data better adjust the applied Butterworth filter, which bridges the known EGM and the new high-degree potential field than the topographic data alone.

  • 9.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Sjöberg, Lars E.
    Royal Institute of Technology (KTH), Stockholm, Sweden.
    Improving gravimetric–isostatic models of crustal depth by correcting for non-isostatic effects and using CRUST2.02013In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 117, p. 29-39Article, review/survey (Refereed)
    Abstract [en]

    The principle of isostasy is important in different fields of geosciences. Using an isostatic hypothesis for estimating the crustal thickness suffers from the more or less incomplete isostatic model and that the observed gravity anomaly is not only generated by the topographic/isostatic signal but also by non-isostatic effects (NIEs). In most applications of isostatic models the NIEs are disregarded. In this paper, we study how some isostatic models related with Vening Meinez's isostatic hypothesis can be improved by considering the NIE. The isostatic gravity anomaly needs a correction for the NIEs, which varies from as much as 494 mGal to − 308 mGal. The result shows that by adding this correction the global crustal thickness estimate improves about 50% with respect to the global model CRUST2.0, i.e. the root mean square differences of the crustal thickness of the best Vening Meinesz type and CRUST2.0 models are 6.9 and 3.2 km before and after improvement, respectively. As a result, a new global model of crustal thickness using Vening Meinesz and CRUST2.0 models is generated. A comparison with an independent African crustal depth model shows an improvement of the new model by 6.8 km vs. CRUST2.0 (i.e. rms differences of 3.0 and 9.8 km, respectively). A comparison between oceanic lithosphere age and the NIEs is discussed in this study, too. One application of this study can be to improve crustal depth in areas where CRUST2.0 data are sparse and bad and to densify the resolution vs. the CRUST2.0 model. Other applications can be used to infer the viscosity of the mantle from the NIEs signal to study various locations around the Earth for understanding complete, over- and under-compensations of the topography.

  • 10.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Sjöberg, Lars E
    Royal Institute of Technology (KTH), Stockholm, Sweden.
    Modelling the density contrast and depth of the Moho discontinuity by seismic and gravimetric–isostatic methods with an application to Africa2012In: Journal of African Earth Sciences, ISSN 0899-5362, Vol. 68, p. 111-120Article in journal (Refereed)
    Abstract [en]

    The crustal thickness (Moho depth) is of interest in several geosciences applications, such as geography, geophysics and geodesy. Usually the crustal depth and density variations are estimated by seismic survey data. As such data collection is very time-consuming and expensive an attractive option could be to use a gravimetric/isostatic model. In this case, realistic estimates for the crustal density and Moho density contrast (MDC) are important. In this study, we first use the seismic crustal thickness of CRUST2.0 model as a known parameter in combination with gravimetric data in estimating the crust–mantle density contrast by the isostatic model of Vening Meinesz–Moritz. We present different models to estimate the MDC and its impact on the modelling of the gravimetric–isostatic Moho depth. The theory is applied to estimate the Moho depth of the African continental crust by using different models for the MDC: (a) constant value (0.6 g/cm3), (b) Pratt–Hayford’s model, (c) CRUST2.0 as input to three gravimetric/isostatic models based on Vening Meinesz–Moritz theory. The isostatic models agree by 5.8–7.1 km in the rms with the regional seismic model at a resolution of 2 x2, and the smallest rms difference at a resolution of 1x1is of

    7.2 km. For comparison, the rms differences of CRUST2.0 and the regional seismic model are 8.8 and 9.1 km at the resolutions of 2 deg (interpolated) and 1 deg respectively. The result suggests that the gravimetric/isostatic Moho model can be used in densification of the CRUST2.0 Moho geometry, and to improve it in areas with poor data.

  • 11.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Sjöberg, Lars E.
    KTH Royal Institute of Technology, Division of Geodesy and Geoinformatics.
    Non-isostatic effects on crustal thickness: A study using CRUST2.0 in Fennoscandia2012In: Physics of the Earth and Planetary Interiors, ISSN 0031-9201, E-ISSN 1872-7395, Vol. 200, p. 37-44Article in journal (Refereed)
  • 12.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Tenzer, Robert
    Institute of Geodesy and Geophysics, School of Geodesy and Geomatics, Wuhan University, Wuhan, China .
    Comparative analysis of Vening-Meinesz Moritz isostatic models using the constant and variable crust-mantle density contrast – a case study of Zealandia2013In: Journal of Earth System Science, ISSN 0973-774X, Vol. 122, no 2, p. 339-348Article in journal (Refereed)
    Abstract [en]

    We compare three different numerical schemes of treating the Moho density contrast in gravimetric inverse problems for finding the Moho depths. The results are validated using the global crustal model CRUST2.0, which is determined based purely on seismic data. Firstly, the gravimetric recovery of the Moho depths is realized by solving Moritz’s generalization of the Vening-Meinesz inverse problem of isostasy while the constant Moho density contrast is adopted. The Pratt-Hayford isostatic model is then facilitated to estimate the variable Moho density contrast. This variable Moho density contrast is subsequently used to determine the Moho depths. Finally, the combined least-squares approach is applied to estimate jointly the Moho depths and density contract based on a priori error model. The EGM2008 global gravity model and the DTM2006.0 global topographic/bathymetric model are used to generate the isostatic gravity anomalies. The comparison of numerical results reveals that the optimal isostatic inverse scheme should take into consideration both the variable depth and density of compensation. This is achieved by applying the combined least-squares approach for a simultaneous estimation of both Moho parameters. We demonstrate that the result obtained using this method has the best agreement with the CRUST2.0 Moho depths. The numerical experiments are conducted at the regional study area of New Zealand’s continental shelf.

  • 13.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute. KTH, Geodesy & Geoinformatics, Stockholm, Sweden.
    Tenzer, Robert
    School of Geodesy and Geomatics, Wuhan University, Wuhan, China.
    Geoid-to-Quasigeoid Separation Computed Using the GRACE/GOCE Global Geopotential Model GOCO02S: A Case Study of Himalayas and Tibet2013In: Terrestrial, Atmospheric and Oceanic Science, ISSN 1017-0839, E-ISSN 2223-8964, Vol. 24, no 1, p. 59-68Article in journal (Refereed)
    Abstract [en]

    The geoid-to-quasigeoid correction has been traditionally computed approximately as a function of the planar Bouguer gravity anomaly and the topographic height. Recent numerical studies based on newly developed theoretical models, however, indicate that the computation of this correction using the approximate formula yields large errors especially in mountainous regions with computation points at high elevations. In this study we investigate these approximation errors at the study area which comprises Himalayas and Tibet where this correction reaches global maxima. Since the GPS-leveling and terrestrial gravity datasets in this part of the world are not (freely) available, global gravitational models (GGMs) are used to compute this correction utilizing the expressions for a spherical harmonic analysis of the gravity field. The computation of this correction can be done using the GGM coefficients taken from the Earth Gravitational Model 2008 (EGM08) complete to degree 2160 of spherical harmonics. The recent studies based on a regional accuracy assessment of GGMs have shown that the combined GRACE/GOCE solutions provide a substantial improvement of the Earth’s gravity field at medium wavelengths of spherical harmonics compared to EGM08. We address this aspect in numerical analysis by comparing the gravity field quantities computed using the satellite-only combined GRACE/GOCE model GOCO02S against the EGM08 results. The numerical results reveal that errors in the geoid-to-quasigeoid correction computed using the approximate formula can reach as much as ~1.5 m. We also demonstrate that the expected improvement of the GOCO02S gravity field quantities at medium wavelengths (within the frequency band approximately between 100 and 250) compared to EGM08 is as much as ±60 mGal and ±0.2 m in terms of gravity anomalies and geoid/quasigeoid heights respectively.

  • 14.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Tenzer, Robert
    Wuhan University, China.
    Sjöberg, Lars
    Royal Institute of Technology (KTH), Stockholm, Sweden.
    Novak, Pavel
    University of West Bohemia, Plzen, Czech Republic.
    Improved global crustal thickness modeling based on the VMM isostatic model and non-isostatic gravity correction2013In: Journal of Geodynamics, ISSN 0264-3707, E-ISSN 1879-1670, Vol. 66, p. 25-37Article in journal (Refereed)
    Abstract [en]

    In classical isostatic models for a gravimetric recovery of the Moho parameters (i.e., Moho depths and density contrast) the isostatic gravity anomalies are usually defined based on the assumption that the topographic mass surplus and the ocean mass deficiency are compensated within the Earth’s crust. As acquired in this study, this assumption yields large disagreements between isostatic and seismic Moho models. To assess the effects not accounted for in classical isostatic models, we conduct a number of numerical experiments using available global gravity and crustal structure models. First, we compute the gravitational contributions of mass density contrasts due to ice and sediments, and subsequently evaluate respective changes in the Moho geometry. Residual differences between the gravimetric and seismic Moho models are then used to predict a remaining non-isostatic gravity signal, which is mainly attributed to unmodeled density structures and other geophysical phenomena. We utilize three recently developed computational schemes in our numerical studies. The apparatus of spherical harmonic analysis and synthesis is applied in forward modeling of the isostatic gravity disturbances. The Moho depths are estimated globally on a 1 arc-deg equiangular grid by solving the Vening-Meinesz Moritz inverse problem of isostasy. The same estimation model is applied to evaluate the differences between the isostatic and seismic models. We demonstrate that the application of the ice and sediment density contrasts stripping gravity corrections is essential for a more accurate determination of the Moho geometry. We also show that the application of the additional non-isostatic correction further improves the agreement between the Moho models derived based on gravity and seismic data. Our conclusions are based on comparing the gravimetric results with the CRUST2.0 global crustal model compiled using results of seismic surveys.

  • 15.
    Bagherbandi, Mohammad
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute. KTH.
    Tenzer, Robert
    Royal Institute of Technology (KTH), Stockholm, Sweden .
    Sjöberg, L.E.
    Wuhan University, Wuhan, China .
    Moho depth uncertainties in the Vening-Meinesz Moritz inverse problem of isostasy2014In: Studia Geophysica et Geodaetica, ISSN 0039-3169, E-ISSN 1573-1626, Vol. 58, no 2, p. 227-248Article in journal (Refereed)
    Abstract [en]

    We formulate an error propagation model based on solving the Vening Meinesz-Moritz (VMM) inverse problem of isostasy. The system ofobservation equations in the VMM model defines the relation between theisostatic gravity data and the Moho depth  by means of a second-order Fredholm integralequation of the first kind. The corresponding error model (derived in aspectral domain) functionally relates the Moho depth errors with the commissionerrors of used gravity and topographic/bathymetric models. The error model alsoincorporates the non-isostatic bias which describesthe disagreement, mainly of systematic nature, between the isostatic andseismic models. The error analysis is conducted at the study area of theTibetan Plateau and Himalayas with the world largest crustal thickness. TheMoho depth uncertainties due to errors of the currently available globalgravity and topographic models are estimated to be typically up to 1-2 km,provided that the GOCE gravity gradient observables improved themedium-wavelength gravity spectra. The errors due to disregarding sedimentarybasins can locally exceed ~2 km. The largest errors (which cause a systematic bias betweenisostatic and seismic models) are attributed to unmodeled mantleheterogeneities (including thecore-mantle boundary) and other geophysical processes. These errors aremostly less than 2 km under significant orogens (Himalayas, Ural), but canreach up to ~10 km under the oceanic crust.

  • 16.
    Benenson, Itzhak
    et al.
    Department of Geography and Human Environment University Tel Aviv.
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Editorial : Bridging the Gap between Urban and Regional Modeling, and Planning Practice2012In: Journal of the Urban and Regional Information Systems Association, ISSN 1045-8077, Vol. 24, no 1, p. 5-7Article in journal (Other academic)
  • 17.
    Benenson, Itzhak
    et al.
    Department of Geography and Human Environment, University Tel Aviv, Tel Aviv, Israel.
    Jiang, BinUniversity of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Special issue: GIS in Spatial Planning2012Collection (editor) (Refereed)
  • 18.
    Brandt, S. Anders
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Lim, Nancy Joy
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Importance of river bank and floodplain slopes on the accuracy of flood inundation mapping2012In: River Flow 2012: Volume 2 / [ed] Rafael Murillo Muñoz, Leiden, The Netherlands: CRC Press / Balkema (Taylor & Francis) , 2012, p. 1015-1020Conference paper (Refereed)
    Abstract [en]

    Effective flood assessment and management depend on accurate models of flood events, which in turn are strongly affected by the quality of digital elevation models (DEMs). In this study, HEC-RAS was used to route one specificwater discharge through the main channel of the Eskilstuna River, Sweden. DEMs with various resolutions and accuracies were used to model the inundation. The results showed a strong positive relationship between the quality of theDEMand the extent of the inundation. However, evenDEMswith the highest resolution produced inaccuracies. In another case study, the Testebo River, the model settings could be calibrated, thanks to a surveyed old inundation event. However, even with the calibration efforts, the resulting inundation extents showed varying degrees of deviation from the surveyed flood boundaries. Therefore, it becomes clear that not only does the resolution of the DEM impact the quality of the results; also, the floodplain slope perpendicular to the river flow will impact the modelling accuracy. Flatter areas exhibited the greatest predictive uncertainties regardless of the DEM’s resolution. For perfectly flat areas, uncertainty becomes infinite.

  • 19.
    El-Mekawy, Mohamed
    et al.
    Fuure Position X.
    Östman, Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Semantic Mapping: An Ontology Engineering Method for Integrating Building Models in IFC and CityGML2010In: 3rd ISDE Digital Earth Summit 12-14 June, 2010, Nessebar, Bulgaria, 2010Conference paper (Refereed)
  • 20.
    El-Mekawy, Mohamed
    et al.
    Department of Computer and Systems Sciences (DSV), Stockholm University, Stockholm, Sweden.
    Östman, Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Hijazi, Ihab
    Department of Urban and Regional Planning Engineering, Faculty of Engineering, An-Najah National University, Nablus, Palestine.
    A Unified Building Model for 3D Urban GIS2012In: ISPRS International Journal of Geo-Information, ISSN 2220-9964, Vol. 1, no 2, p. 120-145Article in journal (Refereed)
    Abstract [en]

    Several tasks in urban and architectural design are today undertaken in a geospatial context. Building Information Models (BIM) and geospatial technologies offer 3D data models that provide information about buildings and the surrounding environment. The Industry Foundation Classes (IFC) and CityGML are today the two most prominent semantic models for representation of BIM and geospatial models respectively. CityGML has emerged as a standard for modeling city models while IFC has been developed as a reference model for building objects and sites. Current CAD and geospatial software provide tools that allow the conversion of information from one format to the other. These tools are however fairly limited in their capabilities, often resulting in data and information losses in the transformations. This paper describes a new approach for data integration based on a unified building model (UBM) which encapsulates both the CityGML and IFC models, thus avoiding translations between the models and loss of information. To build the UBM, all classes and related concepts were initially collected from both models, overlapping concepts were merged, new objects were created to ensure the capturing of both indoor and outdoor objects, and finally, spatial relationships between the objects were redefined. Unified Modeling Language (UML) notations were used for representing its objects and relationships between them. There are two use-case scenarios, both set in a hospital: "evacuation" and "allocating spaces for patient wards" were developed to validate and test the proposed UBM data model. Based on these two scenarios, four validation queries were defined in order to validate the appropriateness of the proposed unified building model. It has been validated, through the case scenarios and four queries, that the UBM being developed is able to integrate CityGML data as well as IFC data in an apparently seamless way. Constraints and enrichment functions are used for populating empty database tables and fields. The motivation scenarios also show the needs and benefits of having an integrated approach to the modeling of indoor and outdoor spatial features.

  • 21.
    El-Mekawy, Mohamed
    et al.
    Future Position X, Gävle, Sweden.
    Östman, Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Shahzad, Khuram
    KTH, Stockholm, Sweden.
    Towards Interoperating CityGML and IFC Building Models: A Unified Model Based Approach2011In: Advances in 3D Geo-Information Sciences / [ed] Kölbe T., König G. & Nagel C., Berlin/Heidelberg: Springer, 2011, p. 73-93Conference paper (Refereed)
    Abstract [en]

    CityGML represents 3D urban objects that can be shared over different applications, whereas, IFC provides a very detailed semantic model for 3D building representations using constructive elements like beams, walls, etc. Attempts have been made to interoperate CityGML and IFC for seeking useful common applications. However, these efforts use a unidirectional method (mostly from IFC to CityGML) for conversion processes. Abidirectional method can lead to development of unified applications in the areas of urban planning, building construction analysis, homeland security, etc.The benefits of these applications clearly appear at the operational level (e.g., cost reduction, unified data-view), and at the strategic level (e.g., crisis management and increasing the analyses capabilities). In this paper, we presentan approach for interoperating CityGML and IFC based on development of aunified building model for converting IFC to CityGML and vice versa. The conversion is a two-steps process in which a model is firstly converted to the unified model and secondly to the target model. Finally, we demonstrate the approach and outcome of each step by a hospital building case that is located in Norrtälje City, north of Stockholm, Sweden.

  • 22.
    El-Mekawy, Mohamed
    et al.
    Future Position X, Gävle, Sweden.
    Östman, Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Shahzad, Khurram
    KTH, Stockholm, Sweden.
    Towards Interoperating CityGML and IFC Building Models: A Unified Model Based Approach2010In: 5th International Conference on 3D GeoInformation / [ed] T. H. Kolbe, G. König, C. Nagel, ISPRS , 2010, no W15, p. 185-185Conference paper (Refereed)
    Abstract [en]

    CityGML represents 3D urban objects that can be shared over different applications, whereas, IFC provides a very detailed semantic model for 3D building representations using constructive elements like beams, walls, etc. Attempts have been made to interoperate CityGML and IFC for seeking useful common applications. However, these efforts use a unidirectional method (mostly from IFC to CityGML) for conversion processes. A bidirectional method can lead to development of unified applications in the areas of urban planning, building construction analysis, homeland security, etc. The benefits of these applications clearly appear at the operational level (e.g., cost reduction, unified data-view), and at the strategic level (e.g., crisis management and increasing the analyses capabilities). In this paper, we present an approach for interoperating CityGML and IFC based on development of a unified building model for converting IFC to CityGML and vice versa. The conversion is a two-steps process in which a model is firstly converted to the unified model and secondly to the target model. Finally, we demonstrate the approach and outcome of each step by a hospital building case that is located in Norrtalje City, north of Stockholm, Sweden.

  • 23.
    Eshagh, M.
    et al.
    K N Toosi University of Technology, Department of Geodesy, Tehran, Iran .
    Bagherbandi, Mohammad
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute. Royal Institute of Technology (KTH), Division of Geodesy and Geoinformatics, Stockholm, Sweden.
    Quality description for gravimetric and seismic moho models of fennoscandia through a combined adjustment2012In: Acta Geodaetica et Geophysica Hungarica, ISSN 1217-8977, E-ISSN 1587-1037, Vol. 47, no 4, p. 388-401Article in journal (Refereed)
    Abstract [en]

    The gravimetric model of the Moho discontinuity is usually derived based on isostatic adjustment theories considering floating crust on the viscous mantle. In computation of such a model some a priori information about the density contrast between the crust and mantle and the mean Moho depth are required. Due to our poor knowledge about them they are assumed unrealistically constant. In this paper, our idea is to improve a computed gravimetric Moho model, by the Vening Meinesz-Moritz theory, using the seismic model in Fennoscandia and estimate the error of each model through a combined adjustment with variance component estimation process. Corrective surfaces of bi-linear, bi-quadratic, bi-cubic and multi-quadric radial based function are used to model the discrepancies between the models and estimating the errors of the models. Numerical studies show that in the case of using the bi-linear surface negative variance components were come out, the bi-quadratic can model the difference better and delivers errors of 2.7 km and 1.5 km for the gravimetric and seismic models, respectively. These errors are 2.1 km and 1.6 km in the case of using the bi-cubic surface and 1 km and 1.5 km when the multi-quadric radial base function is used. The combined gravimetric models will be computed based on the estimated errors and each corrective surface.

  • 24.
    Fawcett, Peter
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Brenner, Mats
    University of Gävle, Library.
    Chinese International Students’ First-year Learning and Teaching Perceptions at the University of Gävle, Sweden2013Report (Other academic)
    Abstract [en]

    Given the accelerating growth in the international student market, Chinese international students are increasingly becoming an important feature of higher education in many countries worldwide. The number of students attending Swedish universities although small compared to more traditional country destinations has, up to recent times, continued to increase. For Swedish universities not so accustomed to teaching and supporting the Chinese students, the challenge is considerable.

    This study explores the learning experiences of Chinese undergraduate students during their first year at the University of Gävle (Sweden). All of the students were young (most 17 to 19) and came from areas of China with strong Confucian heritage cultures. The study draws on previous research and a questionnaire to examine the students’ success in the classroom, how their attitudes to learning evolved, and how they adapted to Swedish culture. The study also discusses students’ opinions as to the academic and support services that have been or could be provided. The questionnaire developed for the study includes ideas and contributions from a United Kingdom university. An Interview Guide was also prepared to facilitate the study and to frame possible follow-up questions to participants.

    The study reveals that the students experienced a wide variety of difficulties. Lack of English language proficiency, communication difficulties, periods of isolation and loneliness together with a lack of social activities all featured significantly. Other areas highlighted included difficulties with academic writing, poor study skills awareness, and difficulties with making friends. On a more positive note, the students showed interest in and an ability to adjust, adapt and gain from a totally different style of teaching and learning. In terms of the implications for the University, these findings suggest that attention should be given in finding ways to improve the overall quality of student learning, teaching and support provided not only for Chinese students but for all international students. In this light, a series of recommendations are presented.

    Recommendations of note are to undertake a longitudinal study and offer an international foundation year programme with English language support services.

  • 25.
    Fritsch, D.
    et al.
    University of Stuttgart, Stuttgart, Germany.
    Mooney, K.
    Dublin Institute of Technology (DIT), Dublin, Ireland.
    Östman, Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    EDUSERV - the education service of EuroSDR: sharing experience for capacity building2012In: ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, 2012, Vol. XXXIX-B6, p. 87-90Conference paper (Refereed)
    Abstract [en]

    This paper describes EduServ, the Education Service of EuroSDR - a European spatial data research organisation whose aim is to address the research needs of spatial data provision in Europe. With a current membership coming from seventeen European countries and a strong working relationship with related European organisations, EuroSDR has amassed considerable experience in addressing the extent and nature of this need. In order to facilitate the transfer of outcomes of EuroSDR research activities to the user domain, e.g. to key personnel in geographic information (GI) production organisations and industry, EuroSDR commenced this annual series of elearning courses in 2002. The Internet courses are preceded by a seminar at which participants meet tutors and receive guidelines for following the courses from their own locations. Delivery of the two-week courses requires an acceptable level of Internet connectivity, which exists in most member countries. EuroSDR is aware, however, that should such courses be shared internationally, other forms of communication will need to be addressed, such as satellite broadcasting. This would require effective collaboration with related organisations with experience with this means of communication. EduServ courses are offered in two successive years. During the courses, participants enjoy access to course tutors with a 24-hour response to queries guaranteed. Thereafter, course material for these courses is made available online. EuroSDR continues to work with past course tutors to ensure that this valuable resource is maintained as an effective and sustainable archive. This paper is aimed at sharing EuroSDR's experience in distance education with the wider scientific community with a view to its applicability to a global audience, whereby instead of sharing expertise within the GI community in Europe, European mapping agencies can share their knowledge and experience with the international GI community.

  • 26.
    Harrie, Lars
    et al.
    Lund University.
    Larsson, Karin
    Lund University.
    Tenenbaum, David
    Lund University.
    Horemuz, Milan
    Royal Institute of Technology (KTH).
    Ridefelt, Hanna
    National mapping and land registration authority, Gävle, Sweden.
    Lysell, Gunnar
    National mapping and land registration authority, Gävle, Sweden.
    Brandt, S. Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Sahlin, Eva A.U.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Adelsköld, Göran
    Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Högström, Mats
    Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Lagerstedt, Jakob
    Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Some strategic national initiatives for the Swedish education in the geodata field2014In: Connecting a Digital Europe through Location and Place: Selected best short papers and posters of the AGILE 2014 Conference, 3‐6 June 2014, Castellón, Spain / [ed] Joaquin Huerta, Sven Schade, Carlos Granell, AGILE Digital Editions , 2014Conference paper (Refereed)
    Abstract [en]

    This paper describes national cooperation in Sweden launched by its universities and authorities, aimed at improving geodata education. These initiatives have been focused upon providing common access to geodata, the production of teaching materials in Swedish and organizing annual meetings for teachers. We argue that this type of cooperation is vital to providing high quality education for a poorly recognized subject in a country with a relatively small population.

  • 27.
    Hedefalk, Finn
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Östman, Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Making Swedish environmental geodata INSPIRE compliant: A harmonization case study2011In: Mapping and Image Science, ISSN 1651-8705, no 3, p. 30-37Article in journal (Refereed)
    Abstract [en]

    The European project Nature-SDIplus has developed data and metadata specifications for three INSPIRE Annex III themes: Habitat and Biotopes, Bio-geographical regions and Species distributions. These serves as a foundation for the thematic groups developing the corresponding INSPIRE specifications. The aim of this study is to test a data harmonization approach to make Swedish environmental geodata and metadata compliant with these specifications. In the harmonization process, we use offline transformations that are split into one spatial and one non-spatial part, and standardized formats to allow vendor neutrality. Moreover, we extend the compliance tests to the data and metadata specifications by validating against both extensible Markup Language (XML)-schema and Schematron. Finally, we identify harmonization processes that may be costly or have negative impacts on data quality. The harmonized data and metadata are thereafter published as network services compliant with OGC Web Service specifications. The output from our method is data and metadata that are valid to the Nature-SDIplus data specifications and metadata profiles. Although the usage of standardized formats facilitates vendor neutrality, the nonspatial transformation procedures expressed in interoperable languages seem to be insufficient to execute all the mapping rules. Therefore, some of these transformations cannot be executed in a vendor neutral environment without modifications. Furthermore, by splitting the harmonization into two manageable parts, we avoid some limitations about XML schema translations in existing spatial transformation tools. Additional findings are: (1) by extending the validation with Schematron tests, we find non-compliances that have been missed during the XML schema tests; (2) costly processes are identified, which are caused by missing elements and by unstructured information given as comments; and (3) degradation of the positional and thematic accuracy occur during the harmonization.

  • 28.
    Hedefalk, Finn
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Östman, Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Robustness of Spatial Databases against Intentional Attacks and Random Errors.2010In: 13th AGILE International Conference on Geographic Information Science 2010, Guimarães, Portugal, 2010Conference paper (Refereed)
  • 29.
    Jia, Tao
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute. School of Remote Sensing and Information Engineering, Wuhan University, China.
    Carling, Kenneth
    Högskolan Dalarna.
    Håkansson, Johan
    Högskolan Dalarna.
    Trips and their CO2 emissions to and from a shopping center2013In: Journal of Transport Geography, ISSN 0966-6923, E-ISSN 1873-1236, Vol. 33, p. 135-145Article in journal (Refereed)
    Abstract [en]

    Previous studies have focused on entire trips within a geographical region, while only a few have examined trips to and from a city landmark. This paper examines trips and their CO2 emissions to and from a shopping center from a time-space perspective, and it further considers how this information can be used in relocation planning. It is a case study in the Borlange city in mid-Sweden where trips to the city's largest shopping mall are scrutinized. We use GPS tracking data of car trips starting and ending at the shopping center. Firstly, we analyze the traffic emission patterns from a time-space perspective where the temporal patterns reveal hourly-based traffic emission dynamics. The spatial analysis uncovers a heterogeneous distribution of traffic emissions in spatial areas and individual street segments. Secondly, we find the observed trips mostly agree with an optimal route in terms of CO2 emissions. Drawing on this finding, we thirdly evaluate the location of the current shopping center by comparing it to two competing locations. We conclude that the two competing locations, being in the vicinity of the current one, would induce an insignificant improvement in terms of CO2 emissions. (C) 2013 Elsevier Ltd. All rights reserved.

  • 30.
    Jia, Tao
    et al.
    KTH.
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Building and analyzing the US airport network based on en-route location information2012In: Physica A: Statistical Mechanics and its Applications, ISSN 0378-4371, E-ISSN 1873-2119, Vol. 391, no 15, p. 4031-4042Article in journal (Refereed)
    Abstract [en]

    From a complex network perspective, this study sets out two aims around the US airport network (USAN) which is built from en-route location information of domestic flights in the US. First, we analyze the structural properties of the USAN with respect to its binary and weighted graphs, and second we explore the airport patterns, which have wide-ranging implications. Results from the two graphs indicate the following. (1) The USAN exhibits scale-free, small-world and disassortative mixing properties, which are consistent with the mainstream perspectives. Besides, we find (2) a remarkable power relationship between the structural measurements in the binary graph and the traffic measurements in the weighted counterpart, namely degree versus capacity and attraction versus volume. On the other hand, investigation of the airport patterns suggests (3) that all the airports can be classified into four categories based on multiple network metrics, which shows a complete typology of the airports. And it further indicates (4) that there is a subtle relationship between the airport traffic and the geographical constraints as well as the regional socioeconomic indicators.

  • 31.
    Jia, Tao
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute. Division of Geoinformatics, Royal Institute of Technology (KTH), Stockholm, Sweden.
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Exploring human activity patterns using taxicab static points2012In: ISPRS International Journal of Geo-Information, ISSN 2220-9964, Vol. 1, no 1, p. 89-107Article in journal (Refereed)
    Abstract [en]

    This paper explores the patterns of human activities within a geographical space by adopting the taxicab static points which refer to the locations with zero speed along the tracking trajectory. We report the findings from both aggregated and individual aspects. Results from the aggregated level indicate the following: (1) Human activities exhibit an obvious regularity in time, for example, there is a burst of activity during weekend nights and a lull during the week. (2) They show a remarkable spatial drifting pattern, which strengthens our understanding of the activities in any given place. (3) Activities are heterogeneous in space irrespective of their drifting with time. These aggregated results not only help in city planning, but also facilitate traffic control and management. On the other hand, investigations on an individual level suggest that (4) activities witnessed by one taxicab will have different temporal regularity to another, and (5) each regularity implies a high level of prediction with low entropy by applying the Lempel-Ziv algorithm.

  • 32.
    Jia, Tao
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute. Division of Geoinformatics, Royal Institute of Technology (KTH), Stockholm, Sweden .
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Carling, Kenneth
    School of Technology and Business Studies, Dalarna University, Borlänge, Sweden .
    Bolin, Magnus
    School of Technology and Business Studies, Dalarna University, Borlänge, Sweden .
    Ban, Yifang
    Division of Geoinformatics, Royal Institute of Technology (KTH), Stockholm, Sweden.
    An empirical study on human mobility and its agent-based modeling2012In: Journal of Statistical Mechanics: Theory and Experiment, ISSN 1742-5468, E-ISSN 1742-5468, no 11, p. P11024-Article in journal (Refereed)
    Abstract [en]

    This paper aims to analyze the GPS traces of 258 volunteers in order to obtain a better understanding of both the human mobility patterns and the mechanism. We report the regular and scaling properties of human mobility for several aspects, and importantly we identify its Levy flight characteristic, which is consistent with those from previous studies. We further assume two factors that may govern the Levy flight property: (1) the scaling and hierarchical properties of the purpose clusters which serve as the underlying spatial structure, and (2) the individual preferential behaviors. To verify the assumptions, we implement an agent-based model with the two factors, and the simulated results do indeed capture the same Levy flight pattern as is observed. In order to enable the model to reproduce more mobility patterns, we add to the model a third factor: the jumping factor, which is the probability that one person may cancel their regular mobility schedule and explore a random place. With this factor, our model can cover a relatively wide range of human mobility patterns with scaling exponent values from 1.55 to 2.05.

  • 33.
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    A short note on data-intensive geospatial computing2011In: Lecture Notes in Geoinformation and Cartography, Berlin: Springer , 2011, p. 13-17Conference paper (Refereed)
  • 34.
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Bottom-up approach to studying the street structure and human movement patterns2010In: Workshop on Movement Research: Are you in the flow?, 2010Conference paper (Other academic)
  • 35.
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Computing the image of the city2012In: Planning Support Tools: Policy analysis, implementation and evaluation: Proceedings of the 7th Int.conf.on Informatics and Urban and Regional planning INPUT / [ed] Campagna M., De Montis A., Isola F., Lai S., Pira C. and Zoppi C., 2012, p. 111-121Conference paper (Refereed)
  • 36.
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Data-intensive geospatial analysis and computation2010In: online proceeding, 2010Conference paper (Refereed)
  • 37.
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Head/tail breaks: A new classification scheme for data with a heavy-tailed distribution2013In: Professional Geographer, ISSN 0033-0124, E-ISSN 1467-9272, Vol. 65, no 3, p. 482-494Article in journal (Refereed)
    Abstract [en]

    This paper introduces a new classification scheme - head/tail breaks - in order to find groupings or hierarchy for data with a heavy-tailed distribution. The heavy-tailed distributions are heavily right skewed, with a minority of large values in the head and a majority of small values in the tail, commonly characterized by a power law, a lognormal or an exponential function. For example, a country's population is often distributed in such a heavy-tailed manner, with a minority of people (e.g., 20 percent) in the countryside and the vast majority (e.g., 80 percent) in urban areas. This heavy-tailed distribution is also called scaling, hierarchy or scaling hierarchy. This new classification scheme partitions all of the data values around the mean into two parts and continues the process iteratively for the values (above the mean) in the head until the head part values are no longer heavy-tailed distributed. Thus, the number of classes and the class intervals are both naturally determined. We therefore claim that the new classification scheme is more natural than the natural breaks in finding the groupings or hierarchy for data with a heavy-tailed distribution. We demonstrate the advantages of the head/tail breaks method over Jenks' natural breaks in capturing the underlying hierarchy of the data. Keywords: data classification, head/tail division rule, natural breaks, scaling, and hierarchy

  • 38.
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    IJGIS International Journal of Geographical Information Science: Special issue on data-intensive geospatial computing2011Collection (editor) (Refereed)
  • 39.
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Making GIScience research more open access2011In: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 25, no 8, p. 1217-1220Article in journal (Other (popular science, discussion, etc.))
  • 40.
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    The Image of the city out of the underlying scaling of city artifacts or locations2013In: Annals of the Association of American Geographers, ISSN 0004-5608, E-ISSN 1467-8306, Vol. 103, no 6, p. 1552-1566Article in journal (Refereed)
    Abstract [en]

    Two fundamental issues surrounding research on the image of the city focus on the city's external and internal representations. The external representation in the context of this article refers to the city itself, external to human minds, whereas the internal representation concerns how the city is represented in human minds internally. This article deals with the first issue; that is, what traits the city has that make it imageable. I develop an argument that the image of the city arises from the underlying scaling of city artifacts or locations. This scaling refers to the fact that, in an imageable city (a city that can easily be imaged in human minds), small city artifacts are far more common than large ones; or, alternatively, low-density locations are far more common than high-density locations. The sizes of city artifacts in a rank-size plot exhibit a heavy-tailed distribution consisting of the head, which is composed of a minority of unique artifacts (vital and very important), and the tail, which is composed of redundant other artifacts (trivial and less important). Eventually, those extremely unique and vital artifacts in the top head or those largest, so to speak, what Lynch called city elements, make up the image of the city. I argue that the ever-increasing amount of geographic information on cities, in particular obtained from social media such as Flickr and Twitter, can turn research on the image of the city, or cognitive mapping in general, into a quantitative manner. The scaling property might be formulated as a law of geography.

  • 41.
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Volunteered geographic information and computational geography: New perspectives2013In: Crowdsourcing Geographic Knowledge: Volunteered Geographic Information (VGI) in Theory and Practice / [ed] Sui D. Elwood S. and Goodchild M, Springer Berlin/Heidelberg, 2013, p. 125-138Chapter in book (Refereed)
    Abstract [en]

    Volunteered geographic information (VGI), one of the most important types of user-generated web content, has been emerging as a new phenomenon. VGI is contributed by numerous volunteers and supported by web 2.0 technologies. This chapter discusses how VGI provides new perspectives for computational geography, a transformed geography based on the use of data-intensive computing and simulations to uncover the underlying mechanisms behind geographic forms and processes. We provide several examples of computational geography using OpenStreetMap data and GPS traces to investigate the scaling of geographic space and its implications for human mobility patterns. We illustrate that the field of geography is experiencing a dramatic change and that geoinformatics and computational geography deserve to be clearly distinguished, with the former being a study of engineering and the latter being a science.

  • 42.
    Jiang, Bin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Why can the image of the city be formed?2013In: Proceedings of the 12th International Conference on GeoComputation, LIESMARS, Wuhan University of Technology Press, 2013Conference paper (Refereed)
  • 43.
    Jiang, Bin
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute. Kavli Institute for Theoretical Physics China (KITPC), Chinese Academy of Sciences, Beijing, China .
    Duan, Yingying
    State Key Laboratory of Resources and Environmental Information System, Chinese Academy of Sciences, Beijing, China .
    Lu, Feng
    State Key Laboratory of Resources and Environmental Information System, Chinese Academy of Sciences, Beijing, China.
    Yang, Tinghong
    Department of Mathematics, Logistical Engineering University, Chongqing, China .
    Zhao, Jing
    Department of Mathematics, Logistical Engineering University, Chongqing, China; Kavli Institute for Theoretical Physics China (KITPC), Chinese Academy of Sciences, Beijing, China.
    Topological structure of urban street networks from the perspective of degree correlations2014In: Environment and Planning, B: Planning and Design, ISSN 0265-8135, E-ISSN 1472-3417, Vol. 41, no 5, p. 813-828Article in journal (Refereed)
    Abstract [en]

    Many complex networks demonstrate a phenomenon of striking degree correlations: that is, a node tends to link to other nodes with similar (or dissimilar) degrees. From the perspective of degree correlations, in this paper we attempt to characterize topological structures of urban street networks. We adopted six urban street networks (three European and three North American), and converted them into network topologies in which nodes and edges represent individual streets and street intersections, respectively, and compared the network topologies with three reference network topologies (biological, technological, and social). The urban street network topologies (with the exception of Manhattan) showed a consistent pattern that distinctly differs from the three reference networks. The topologies of urban street networks lack striking degree correlations in general. Through reshuffling the network topologies towards, for example, maximum or minimum degree correlations while retaining the initial degree distributions, we found that all the surrogate topologies of the urban street networks, as well as the reference ones, tended to deviate from small-world properties. This implies that the initial degree correlations do not have any positive or negative effect on the networks’ performance or functions. 

  • 44.
    Jiang, Bin
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Jia, Tao
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Agent-based simulation of human movement shaped by the underlying street structure2011In: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 25, no 1, p. 51-64Article in journal (Refereed)
    Abstract [en]

    Relying on random and purposive moving agents, we simulated human movement in large street networks. We found that aggregate flow, assigned to individual streets, is mainly shaped by the underlying street structure, and that human moving behavior (either random or purposive) has little effect on the aggregate flow. This finding implies that given a street network, the movement patterns generated by purposive walkers (mostly human beings) and by random walkers are the same. Based on the simulation and correlation analysis, we further found that the closeness centrality is not a good indicator for human movement, in contrast to a long-standing view held by space syntax researchers. Instead we suggest that Google's PageRank and its modified version (weighted PageRank), betweenness and degree centralities are all better indicators for predicting aggregate flow.

  • 45.
    Jiang, Bin
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Jia, Tao
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Zipf's law for all the natural cities in the United States: a geospatial perspective2011In: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 25, no 8, p. 1269-1281Article in journal (Refereed)
    Abstract [en]

    This article provides a new geospatial perspective on whether or not Zipf's law holds for all cities or for the largest cities in the United States using a massive dataset and its computing. A major problem around this issue is how to define cities or city boundaries. Most of the investigations of Zipf's law rely on the demarcations of cities imposed by census data, for example, metropolitan areas and census-designated places. These demarcations or definitions (of cities) are criticized for being subjective or even arbitrary. Alternative solutions to defining cities are suggested, but they still rely on census data for their definitions. In this article we demarcate urban agglomerations by clustering street nodes (including intersections and ends), forming what we call natural cities. Based on the demarcation, we found that Zipf's law holds remarkably well for all the natural cities (over 2–4 million in total) across the United States. There is little sensitivity for the holding with respect to the clustering resolution used for demarcating the natural cities. This is a big contrast to urban areas, as defined in the census data, which do not hold stable for Zipf's law.

  • 46.
    Jiang, Bin
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Liu, Xintao
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Automatic generation of the axial lines of urban environments to capture what we perceive2010In: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 24, no 4, p. 545-558Article in journal (Refereed)
    Abstract [en]

    Based on the concepts of isovists and medial axes, we developed a set of algorithms that can automatically generate axial lines for representing individual linearly stretched parts of open space of an urban environment. Open space is the space between buildings where people can freely move around. The generation of the axial lines has been a key aspect of space syntax research, conventionally relying on hand-drawn axial lines of an urban environment, often called axial map, for urban morphological analysis. Although various attempts have been made towards an automatic solution, few of them can produce the axial map that consists of the least number of longest visibility lines, and none of them really works for different urban environments. Our algorithms provide a better solution than existing ones. Throughout this article, we have also argued and demonstrated that the axial lines constitute a true skeleton, superior to medial axes, in capturing what we perceive about the urban environment.

  • 47.
    Jiang, Bin
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Liu, Xintao
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Computing the fewest-turn map directions based on the connectivity of natural roads2011In: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 25, no 7, p. 1069-1082Article in journal (Refereed)
    Abstract [en]

    In this article, we introduce a novel approach to computing the fewest-turn map directions or routes based on the concept of natural roads. Natural roads are joined road segments that perceptually constitute good continuity. This approach relies on the connectivity of natural roads rather than that of road segments for computing routes or map directions. Because of this, the derived routes possess the fewest turns. However, what we intend to achieve are the routes that not only possess the fewest turns but are also as short as possible. This kind of map direction is more effective and favored by people because they bear less cognitive burden. Furthermore, the computation of the routes is more efficient because it is based on the graph encoding the connectivity of roads, which is substantially smaller than the graph of road segments. We experimented on eight urban street networks from North America and Europe to illustrate the above-stated advantages. The experimental results indicate that the fewest-turn routes possess fewer turns and shorter distances than the simplest paths and the routes provided by Google Maps. For example, the fewest-turn-and-shortest routes are on average 15% shorter than the routes suggested by Google Maps, whereas the number of turns is just half as much. This approach is a key technology behind FromToMap.org – a web mapping service using openstreetmap data.

  • 48.
    Jiang, Bin
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Liu, Xintao
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Scaling of geographic space from the perspective of city and field blocks and using volunteered geographic information2012In: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 26, no 2, p. 215-229Article in journal (Refereed)
    Abstract [en]

    Scaling of geographic space refers to the fact that for a large geographic area its small constituents or units are much more common than the large ones. This article develops a novel perspective to the scaling of geographic space using large street networks involving both cities and countryside. Given a street network of an entire country, we decompose the street network into individual blocks, each of which forms a minimum ring or cycle such as city blocks and field blocks. The block sizes demonstrate the scaling property, that is, far more small blocks than large ones. Interestingly, we find that the mean of all the block sizes can easily separate between small and large blocks –a high percentage (e.g., 90%) of smaller ones and a low percentage (e.g., 10%) of larger ones. Based on this regularity, termed as the head/tail division rule, we propose an approach to delineating city boundaries by grouping the smaller blocks. The extracted city sizes for the three largest European countries (France, Germany, and United Kingdom) exhibit power law distributions. We further define the concept of border number as a topological distance of a block far from the outmost border to map the center(s) of the country and the city. We draw an analogy between a country (or a city or geographic space in general) and a complex organism like the human body or the human brain to further elaborate on the power of this block perspective in reflecting the structure or patterns of geographic space.

  • 49.
    Jiang, Bin
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Liu, Xintao
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Jia, Tao
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Scaling of Geographic space as a universal rule for map generalization2013In: Annals of the Association of American Geographers, ISSN 0004-5608, E-ISSN 1467-8306, Vol. 103, no 4, p. 844-855Article in journal (Refereed)
    Abstract [en]

    Map generalization is a process of producing maps at different levels of detail by retaining essential properties of the underlying geographic space. In this paper, we explore how the map generalization process can be guided by the underlying scaling of geographic space. The scaling of geographic space refers to the fact that in a geographic space small things are far more common than large ones. In the corresponding rank-size distribution, this scaling property is characterized by a heavy tailed distribution such as a power law, lognormal, or exponential function. In essence, any heavy tailed distribution consists of the head of the distribution (with a low percentage of vital or large things) and the tail of the distribution (with a high percentage of trivial or small things). Importantly, the low and high percentages constitute an imbalanced contrast, e.g., 20 versus 80. We suggest that map generalization is to retain the objects in the head and to eliminate or aggregate those in the tail. We applied this selection rule or principle to three generalization experiments, and found that the scaling of geographic space indeed underlies map generalization. We further relate the universal rule to T\"opfer's radical law (or trained cartographers' decision making in general), and illustrate several advantages of the universal rule. Keywords: Head/tail division rule, head/tail breaks, heavy tailed distributions, power law, and principles of selection

  • 50.
    Jiang, Bin
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Okabe, Atsuyuki
    Aoyama Gakuin University, Tokyo, Japan.
    Different ways of thinking about street networks and spatial analysis2014In: Geographical Analysis, ISSN 0016-7363, E-ISSN 1538-4632, Vol. 46, no 4, p. 341-344Article in journal (Other academic)
12 1 - 50 of 96
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