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  • 251.
    Kuljanin, Emir
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Utveckling av mobilt köpstöd till skogsindustrin2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Avdelningen Forestry på Consultants to Government and Industry (CGI) i Gävle utvecklar många olika programvaror som används i skogsindustrin. Med tiden har det uppstått ett behov av ett förenklat program som kan användas i mobiltelefoner. CGI ville att en prototyp tas fram för utvärdering, samt att en förenklad undersökning görs med avseende på vad som är lämpligast emellan en mobil applikation (s.k. ”app”) eller en mobilanpassad webbapplikation (webbapp). Vid projektets slut har en Windows 8 mobilapp utvecklats samt en mindre undersökning fullgjorts. Undersökningen visar att en webbapp är det ekonomiska alternativet, men att mobila appar utvecklade för sin specifika plattform uppnår högre kvalité.

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    Utveckling av mobilt köpstöd till skogsindustrin
  • 252.
    Kushnir, Julia
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    ArchiveQ: en applikationsmodell för sökning och hantering av geodata utifrån tidpunken2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I dagens samhälle har Geografiska Informations System (GIS) blivit allt mer integrerade inom tekniken och kan appliceras inom alla situationer då position är tillgänglig. Syftet med detta arbete är att undersöka de befintliga metoderna som hanterar tidsinformation inom GIS och att hitta en sätt som underlättar hantering av tidsinformation på ett nytt sätt.

    Resultatet av detta arbete är en applikationsmodell som föreslår ett alternativt sätt att skapa och lägga till tidstämplar för geodatainformation, samt hur dessa kan hanteras inom applikationssystemet. Det har även skapats en demo webbapplikation som visualiserar ett alternativt sätt att söka efter data utifrån de nyskapade tidsstämplarna.

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  • 253.
    Lagemyr, Elisabeth
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Digital forensik: "Hide and Seek" på hårddisken2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Den tekniska utvecklingen av allt mer komplexa filsystem samt ökad lagringskapacitet på medier försvårar arbetet med att finna samt återskapa förlorade filer. Detta medför att de verktyg som används inom området ständigt måste utvecklas för att möta upp denna komplexitet.

    När filer ”raderas” av användaren hanterar filsystemet denna process på olika vis beroende på vilken typ av radering som utförts. Möjligheterna att återskapa dessa filer underlättas genom en grundläggande kunskap om filsystemets arkitektur samt de osynliga processer som sker.

    Inom den profession, till exempel digital forensik, där det insamlande materialet har krav att klara rättspraxis används olika metoder för att bevara materialets integritet. De kommersiella verktyg som används är utvecklade för att bemöta de krav som ställs inom rättsliga processer. Denna undersökning anammade till viss del det förfarande som utövas inom den digitala forensiken.

    Huvudsyftet med denna studie var att undersöka möjligheterna att återskapa ”raderade” filer samt belysa eventuella differenser utifrån olika scenarier. Utifrån huvudsyftet tog undersökningen sikte på att vägleda datoranvändarna till att anamma de metoder som undersökts.

    Genom den litteraturöversikt som studerades samt de experiment som utfördes sammanfattades resultatet kvantitativt där återfunna samt återskapade filer sammanställdes. De resultat som denna undersökning kom fram till var att goda möjligheter finns för att återskapa de borttagna filerna. Vidare anses att datoranvändare mycket väl kan använda de metoder som ingick i denna undersökning för att återskapa sina ”raderade” filer.

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  • 254.
    Larsson, Andreas
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences.
    Nygren, Tony
    University of Gävle, Department of Mathematics, Natural and Computer Sciences.
    Transaktionshantering med samtidighetskontroll i databaser2006Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    Rapporten handlar om databaser och olika problem som kan uppstå under arbetet i den. Transaktionshantering är en viktig del av databashantering. Vad händer när två transaktioner försöker att komma åt samma dataobjekt? Vad händer när det uppstår deadlocks och hur hanteras dessa?

    Vilka metoder finns det för att få arbetet i en databas att flyta utan att det uppstår några kollisioner mellan transaktioner. Vilka av dessa metoder passar bäst i vilka databaser. Det finns många olika sätt att lösa dessa problem på. Några av dessa är läs- och skrivlås samt tvåfas lås. Alla dessa lås har olika fördelar och nackdelar, ett säkert lås som skyddar väl mot deadlocks kan orsaka längre väntetider. Vad som väljs beror mycket på vad databasen ska användas till. Rapporten avslöjar att användare ofta inte behöver lägga sig i hur databashanterare låser information, däremot är det viktigt att välja när och var låsen ska läggas. För många lås skapar prestandaproblem medan för få lås kan orsaka att datan blir korrupt.

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    FULLTEXT01
  • 255.
    Larsson, Karl
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Mobile Devices in Business Intelligence2013Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    With mobile solutions becoming more requested in the IT world, Business Intelligence is no different. This thesis examines and tests the mobile solutions for Microsoft BI, QlikView and SAP Business Objects to see if it can be used by the Sandvik Group. The tests have consisted of creating standard simple reports for the different platforms, evaluate them and then compare their functions and looks on iPad and computers. During this work it has been stated that all platforms supports mobility quite well and the recommendation is to start using it as soon as possible.

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  • 256.
    Larsson, Karolina
    et al.
    Stockholms stad.
    Paasch, Jesper M.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Paulsson, Jenny
    Conversion of 2D Analogue Cadastral Boundary Plans into 3D Digital Information: problems and challenges illustrated by a Swedish case2018In: 6th International FIG 3D Cadastre Workshop, 2018, p. 75-94Conference paper (Other academic)
    Abstract [en]

    The possibility of forming 3D property units has not existed for a long time in Sweden. The legislation was introduced in 2004 and in 2009 the addition of apartment ownership (condominium) was added. Even though the demand for 3D property formation has not been as high yet as initially expected, there seems to be an increased interest in and demand for it today. The use of 3D property creates a need for 3D registration and visualization of the property units, which can involve difficulties in e.g. representation and storage of 3D real property data, such as the legal boundaries and real property rights connected to the property.However, even if 3D digital information is used in the real property formation process the 3D properties are still registered using two–dimensional documentation. An ongoing study, which is a part of a project testing 3D data, see Andree et al. (2018a; 2018b) and Tarandi (2017), is focusing on visualization of 3D cadastral boundaries.This paper discusses problems and challenges concerning the conversion of 2D analogue cadastral boundary plans into 3D digital information and is based on experiences being gained in a research project on visualization of 3D property boundaries in Sweden, see Andree et al. (2018a; 2018b). A newly constructed sports– and event arena in Stockholm where 3D properties are involved is used as a case study in the project to illustrate the process and the problems related to it. Focus lies here on legal issues, although other aspects will be mentioned as well.The legal foundations for 3D property formation in Sweden are primarily the Swedish Land Code (SFS, 1970:944) and the Real Property Formation Act (SFS, 1970:988). The rights, restrictions and responsibilities, RRRs, are registered in the national Real Property Register, which also includes registration in the two–dimensional digital cadastral index map.A description of the process of forming 3D property is included in the paper regarding the documents and parties involved. In the present cadastral processes concerning new 3D property formation a CAD drawing containing 3D real property boundaries is often supplied by the developer/entrepreneur. However, the 3D cadastral representation and the documentation in the cadastral dossier is recorded in 2D (El–Mekawy, Paasch and Paulsson, 2014). The CAD file may – or may not - be archived for future use by the Cadastral authority. We therefore sometimes may have to interpret two–dimensional data and convert it to be used in a 3D environment, e.g. BIM. This paper illustrates and exemplifies with some experiences of interpreting the cadastral dossiers for presentation in a 3D digital environment.Current legislation has to be investigated and interpreted to be able to add or transform into using 3D models as part of cadastral decisions in Sweden. New regulations also may have to be introduced and analysed. In this paper some of the legal issues that need to be addressed are mentioned, however more work needs to be done in order to get answers to what changes may be needed regarding legislation on this matter.

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  • 257.
    Larsson, Nichlas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Realistic Lighting in Autodesk Maya with Mental Ray Area Light2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The knowledge on how to create realistic lighting in computer graphics is one part that sets a realistic scene apart from one that can easily be spotted to being made in a computer. There are however many methods to reach realistic results with lighting. In this research, the area of focus is how to achieve it with Mental Rays Area Lights using Autodesk Maya. The process will first be explained with a simple scene where the results of some of the most relevant settings will be explained. Then, those techniques will be applied in two scenes to obtain a realistic result. The quality of light is however not only dependent on the lighting itself, but also on the material properties which would be the next logical step to future research which will not be taken into consideration in the span of this paper.

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  • 258.
    Larsson, Pernilla
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Discerning Emotion Through Movement: A study of body language in portraying emotion in animation2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Animators are so often taught more about how to perfect their animations than toconsider what it is that makes the animation come alive. They work away withprinciples and physics, sometimes completely overlooking a characterscommunication tools. The following thesis is a study of emotive expressive bodylanguage and its purpose in animation. The project studies various angles of bodylanguage, in an attempt at summarizing key features that could work as guidelinesfor animators in the future. It deals with the role of body language in animation andwhy it is necessary for a more realistic feel in the animation. As well as the brieflymentioning the 12 animation principles, on their necessity and faults in the matter.The thesis is divided into a theoretical investigation and a practical experiment. Theintention was to create a set of key features for the use of as tools and guides forfresh animators to understand and translate emotion into their animations. Theresults indicate the power of body language and its versatility as a tool, puttingemphasis on why it ought not to be neglected.

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  • 259.
    Larsson, Robin
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Anbudskalkylering: utveckling av ett Java EE-baserat system2009Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Ett konsultföretag får in anbudsförfrågningar och måste därmed göra kalkyler för dessa förfrågningar. Med hjälp av ett webbaserat system där en anställd kan göra kalkyleringar kan företaget få ett gemensamt sätt att arbeta och uppföljningen underlättas. Systemet som har skapats ger användare möjlighet att göra anbudskalkyler genom en överskådlig och lättarbetad webbsida, där man kan se förhållandet mellan företagets kostnad gentemot kundpriset. All information lagras persistent i en databas för att möjliggöra uppföljning och synkronisering med andra system som används på företaget.

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  • 260.
    Larsson, Robin
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Davik, Martin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    WP-Edit2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Det här är till för att skapa ett system där andra webbutvecklare kunde skapa sina hemsidor online. Det webbutvecklaren inte behöver tänka på är att ha en egen webbserver, vilket kan vara ett problem för många om dom sitter vid datorer med begränsade rättigheter så att dom inte kan ladda ner och installera en webbserver. En annan bra fördel är att webbutvecklaren kan logga in vart som helst, när som helst och redigera koden till en hemsida. Skulle webbutvecklaren vilja ha sitt projekt på en egen webbserver, går det enkelt att ladda ner projektet.

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  • 261.
    Leetmaa, Benjamin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    En integration av betalningssystem på hemsida2011Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Detta projekt drevs på uppdrag av Optikbutiken som behövde en tjänst där mankunde betala sin order med hjälp av kreditkort på deras aktuella hemsida. Det härprojektet gick ut på att integrera DIBS vilket är ett betalsystem för kreditkort.Utvecklingen skedde i Visual Studio miljö. De krav som ställdes upp för det härprojektet blev uppfyllda.

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  • 262.
    Leetmaa, Tobias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Web services: en integration av CRM och kundzon2010Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Detta projekt drevs på uppdrag av Flex Datasystem som behövde en vidareutveckling av deras aktuella hemsida. Här finns bland annat möjlighet att direkt ladda ner uppdateringar för kundernas program. Problemet var att hemsidan inte innehöll någon information om uppdateringarna. Kunderna måste då vända sig direkt till supporten för att få information om vad som har åtgärdats. Det här projektet gick ut på att utveckla en funktionalitet som, med automatik, publicerar information om varje uppdatering. Informationen skulle föras över från Flex Datasystems interna system till kundzonen med hjälp av en webbtjänst. Utvecklingen skedde mestadels i Visual Studio miljö. I projektets början infördes några nya funktioner till företagets interna system. Därefter skapades själva webbtjänsten och till sist lades en ny sida till på företagets hemsida som använde sig av denna webbtjänst. De krav som ställdes upp för det här projektet blev uppfyllda. Det visade sig att användandet av en webbtjänst fungerade mycket bra för det här ändamålet.

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    FULLTEXT01
  • 263.
    Leffler, Otto
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Automatic Character Rigging in Maya2009Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Detta arbete kommer att handla om att skapa ett system för att automatiseraprocessen att skapa en karaktärsrig i programmet Maya. Med hjälp av programmets inbyggda programmeringsspråk MEL kommer systemet, via ett grafiskt gränssnitt, skapa just det resultat som användaren efterfrågar.Resultatet är ett verktyg som kan skapa en komplett karaktärsrig på under 3 minuters tid! Ett arbete som annars kan ta flera dagar.

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  • 264.
    Li, Guancong
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Postage stamp recognition using image processing2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Postage stamp is widely consumed in our daily life. In most of the cases, citizens need to purchase stamps in the post office or the local shop and may even need to wait in a long queue. This paper provides a stamp recognition system for supporting auto postage stamp selling machine, in order to convenient citizens and save labor cost for shops. Both citizens and stamp collectors can benefit from this system. This recognition system uses image processing is programmed using MATLAB®. Having scanned different pieces of postage stamps, our system could detect and recognize which type each piece of postage stamp belongs to. Besides, the coordinate information of each piece of stamp can be accessed  for localization.

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    Thesis_GuancongLi
  • 265.
    Li, Sheng
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    An Evaluation of Image Inpainting Algorithms2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Image inpainting is a technique to repair damaged images or to remove/replace select regions. It was used to repair old artwork. It is also a part of movie special effects. With the extended application of electronic products, a lot of work done on mobile devices. But many algorithms may be unsuitable for mobile devices. The purpose of this work is to present an evaluation of several algorithms of image inpainting created in the past. Two classes of algorithms: Partial Differential Equations (PDEs) based algorithms and Exemplar-Based algorithms. The results show the advantages and disadvantages.

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    Bachelor Thesis by Sheng Li
  • 266.
    Li, Tao
    University of Gävle, Department of Technology and Built Environment.
    Spatial Data Infrastructure (SDI) in China: Some potentials and shortcomings2008Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    A Spatial Data Infrastructure (SDI) is required to make the spatial data be fully used and well shared by the society. In China, SDI’s has also been established progressively. A thorough understanding of the potentials and shortcomings about SDI in China has a positive significance to clearly identify the future direction and actions.In order to find out the potentials and shortcomings of SDI in China, the current situation of SDI and SDI in China have been assessed through literature review and interview. Then a Strengths, Weaknesses, Opportunities and Threats (SWOT) analysis has been developed. Based on the current experiences of SDI development in China, the thesis concludes that China have a good potential to develop its SDI function. It also points out that there still are some weaknesses needed to be surmounted, such as: lacking advanced technology, data duplication, and lack of skilled workforce. There is a big room and capability to improve the development of Chinese SDI well in the future.

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  • 267.
    Liang, Cao
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Automatic Tag Recognition in Sport Events2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
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    9008283518-thesis-2013
  • 268.
    Lim, Nancy J.
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Sahlin, Eva A. U.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Brandt, S. Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    A cartographic framework for visualising flood uncertainties2018In: Article in journal (Other academic)
  • 269.
    Lim, Nancy J.
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Seipel, Stefan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Brandt, S. Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Assessment of spatial-based decisions and user perspectives in utilisation of flood certainty mapsManuscript (preprint) (Other academic)
  • 270.
    Lim, Nancy Joy
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Modelling, mapping and visualisation of flood inundation uncertainties2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Flood maps showing extents of predicted flooding for a given extreme event have wide usage in all types of spatial planning tasks, as well as serving as information material for the public. However, the production processes that these maps undergo (including the different data, methods, models and decisions from the persons generating them), which include both Geographic Information Systems (GIS) and hydraulic modelling, affect the map’s content, and will be reflected in the final map. A crisp flood boundary, which is a common way of representing the boundary in flood maps, may therefore not be the best representation to be used. They provide a false implication that these maps are correct and that the flood extents are absolute, despite the effects of the entire modelling in the prediction output. Hence, this research attempts to determine how flood prediction outputs can be affected by uncertainties in the modelling process. In addition, it tries to evaluate how users understand, utilise and perceive flood uncertainty information. 

    Three main methods were employed in the entire research: uncertainty modelling and analyses; map and geovisualisation development; and user assessment. The studies in this work showed that flood extents produced were influenced by the Digital Elevation Model (DEM) resolution and the Manning’s  used. This effect was further increased by the topographic characteristic of the floodplain. However, the performance measure used, which quantify how well a model produces result in relation to a reference floor boundary, had also biases in quantifying outputs. Determining the optimal model output, therefore, depended on outcomes of the goodness-of-fit measures used.

     In this research, several ways were suggested on how uncertainties can be visualised based on the data derived from the uncertainty assessment and by characterising the uncertainty information. These can be through: dual-ended maps; flood probability maps; sequential maps either highlighting the degrees of certainty (certainty map) or degrees of uncertainty (uncertainty map) in the data; binary maps; overlain flood boundaries from different calibration results; and performance bars. Different mapping techniques and visual variables were used for their representation. These mapping techniques employed, as well as the design of graphical representation, helped facilitate understanding the information by the users, especially when tested during the evaluations. Note though that there were visualisations, which the user found easier to comprehend depending on the task given. Each of these visualisations had also its advantages and disadvantages in communicating flood uncertainty information, as shown in the assessments conducted. Another important aspect that came out in the study was how the users’ background influence decision-making when using these maps. Users’ willingness to take risks depended not only on the map, but their perceptions on the risk itself. However, overall, users found the uncertainty maps to be useful to be incorporated in planning tasks.

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  • 271.
    Lim, Nancy Joy
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Brandt, S. Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Seipel, Stefan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science. Division of Visual Information and Interaction, Department of Information Technology, Uppsala University, Uppsala, Sweden.
    Visualisation and evaluation of flood uncertainties based on ensemble modelling2016In: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 30, no 2, p. 240-262Article in journal (Refereed)
    Abstract [en]

    This study evaluates how users incorporate visualisation of flood uncertainty information in decision-making. An experiment was conducted where participants were given the task to decide building locations, taking into account homeowners’ preferences as well as dilemmas imposed by flood risks at the site. Two general types of visualisations for presenting uncertainties from ensemble modelling were evaluated: (1) uncertainty maps, which used aggregated ensemble results; and (2) performance bars showing all individual simulation outputs from the ensemble. Both were supplemented with either two-dimensional (2D) or three-dimensional (3D) contextual information, to give an overview of the area.The results showed that the type of uncertainty visualisation was highly influential on users’ decisions, whereas the representation of the contextual information (2D or 3D) was not. Visualisation with performance bars was more intuitive and effective for the task performed than the uncertainty map. It clearly affected users’ decisions in avoiding certain-to-be-flooded areas. Patterns to which the distances were decided from the homeowners’ preferred positions and the uncertainties were similar, when the 2D and 3D map models were used side by side with the uncertainty map. On the other hand, contextual information affected the time to solve the task. With the 3D map, it took the participants longer time to decide the locations, compared with the other combinations using the 2D model.Designing the visualisation so as to provide more detailed information made respondents avoid dangerous decisions. This has also led to less variation in their overall responses.

  • 272.
    Lim, Nancy Joy
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Sahlin, Eva
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Quantification, classification and mapping of spatial uncertainties of floods2017Conference paper (Refereed)
    Abstract [en]

    In flood modelling studies, spatial uncertainties may be visualised differently. This will rely on the characteristics of the information produced from the quantification method applied, which may vary depending on the type of model uncertainty taken into account. It is important to be able to characterise and generally classify the different types of spatial uncertainty information in hydraulic model results, because this can help determine how they can be best represented and visualised.

    In this paper, two methods of quantifying uncertainties were employed to derive uncertainty information. The first was ensemble-based modelling, which combined the results of 100 simulations considering the effects of the Digital Elevation Model (DEM) and Manning’s roughness coefficient to the model output. Each result from the individual model run was assessed on how likely it depicted the spatial extent of an observed flood event. Afterwards, the results were weighted and aggregated. In the second method, the most optimal output based on a series of calibrations from one-dimensional flood modelling was used and applied with the empirical disparity-distance equation to account for further errors brought about by the resolution of the underlying DEM and the slope. The equation was implemented with an algorithm that created uncertainty zones based on the 95% prediction confidence. The resulting information from the two quantification methods were then classified, discretised and visualised using different map types, visual variables, and overlay techniques.

    Based on these results, four types of uncertainty information for flood modelling were produced that can be classified according to the characteristics of the data they show: (1) diverging, which is distinguished by two opposing conditions (certain to be dry and flooded) and a middle condition (highly uncertain); (2) sequential, where values range from lowest (uncertain) to highest (certain); (3) multiple calibration results, which show simultaneously the flood extents produced using different parameters for comparative purposes; and, (4) inundation zones which identify areas that are both certain and uncertain to be flooded.

    The results from both diverging and sequential uncertainty information were presented as continuous and discrete data in choropleth and graduated symbol maps. The gradation from uncertain-to-certain conditions was displayed using lightest-to-darkest colour and/or smallest-to-largest point symbols. With certainty/uncertainty zone, the binary statuses were represented in choropleth maps as: (a) blue/red colours; (b) organised/disorganised arrangements; and, (c) fine/coarse grain textures. For multiple calibration results, isopleths maps were used with a combination of at least two visual variables (size, shape, colour) to emphasise the differences in the lines, and facilitate visual comparison of results.

    Furthermore, since giving geographic context to flood uncertainty is an important aspect in the visualisation, three types of overlay were considered: map pairs, sequential and bivariate representations. Sequential representation worked well for all map types. Bivariate maps, on the other hand, were best for uncertainty represented as [one-coloured] symbol, texture, arrangement and linear features, which do not obscure the information behind. The background map had also to be displayed with increased transparency to prevent its dominance over the uncertainty data. Map pairs were the most suitable for choropleth maps using fill colour in order to avoid problems caused by colour blending when two maps are overlain. 

    Classification of the uncertainty information facilitated the choice of data representation. Even when using other quantification methods, hydraulic modellers can adopt the suggested visualisation using similar characteristic data.  This can be an initial step in producing guidelines for flood uncertainty visualisation. Moreover, testing the effectiveness of these visualisations can be the next relevant step to see how the information is communicated, interpreted and used, e.g. in spatial planning, flood risk management and insurance policies.

  • 273.
    Lim, Nancy Joy
    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.
    Åhlén, Julia
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Urban and regional planning/GIS-institute.
    Seipel, Stefan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Geovisualisation of uncertainty in simulated flood maps2014In: Proceedings of the International Conferences on Interfaces and Human Computer Interaction 2014, Game and Entertainment Technologies 2014 and Computer Graphics, Visualization, Computer Vision and Image Processing 2014 - Part of the Multi Conference on Computer Science and Information Systems, MCCSIS 2014 / [ed] Katherine Blashki and Yingcai Xiao, IADIS Press , 2014, p. 206-214Conference paper (Refereed)
    Abstract [en]

    The paper presents a three-dimensional (3D) geovisualisation model of uncertainties in simulated flood maps that can help communicate uncertain information in the data being used. An entropy-based measure was employed for uncertainty quantification. In developing the model, Visualisation Toolkit (VTK) was utilised. Different data derived from earlier simulation study and other maps were represented in the model. Cartographic principles were considered in the map design. A Graphical User Interface (GUI), which was developed in Tkinter, was also created to further support exploratory data analysis. The resulting model allowed visual identification of uncertain areas, as well as displaying spatial relationship between the entropy and the slope values. This geovisualisation has still to be tested to assess its effectiveness as a communication tool. However, this type of uncertainty visualisation in flood mapping is an initial step that can lead to its adoption in decision-making when presented comprehensively to its users. Thus, further improvement and development is still suggested for this kind of information presentation.

  • 274.
    Lin, Shaoye
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Sang, Lin
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Smoke Simulation with Perlin Noise2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This work is studying real-time generation of smoke simulation based on a particle system. In order to enhance the realism of the effect, we used texture mapping (Perlin noise) and transparency disturbance to shade the 3D smoke. Furthermore, it uses simple physical function to simulate smoke movement. Classical smoke simulation is using a great amount of particles which makes computing more complex. Compared with traditional methods, the method we propose can generate realistic visual effect of smoke in real-time and reduce the time consumed.

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    Smoke Simulation with Perlin Noise
  • 275.
    Lin, Xinze
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Vision-based Tracking for Intuitive Interaction on Webpages2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Vision-based  tracking  technique  provides  intuitive  experience  for  users  to  interact with their computers. However, such technique seldom appears on web applications that can be widely accessed by average users. The purpose of this paper is to suggest a  technique  that will enable more users  to engage  in the  intuitive  interaction on  the Web.  In order  to achieve  this, a vision based  tracking system  is  built. The  tracking system can  be used by different  types of web applications, so  that a wide  range of users can access this technique.

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    FULLTEXT02
  • 276. Lind, M.
    et al.
    Seipel, Stefan
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Mattiason, C.
    Displaying meta-information in context2001In: Behavior and Information Technology, ISSN 0144-929X, E-ISSN 1362-3001, Vol. 20, no 6, p. 427-432Article in journal (Refereed)
    Abstract [en]

    Very often information exists that would be helpful for process control operators if it could be presented in the context they work in-the process graphics. Examples are instructional material, visualizations of automated sequences, output from knowledge-based systems or simply annotations that one team of operators wants to communicate with another. Several existing distortion techniques were reviewed that would allow the ordinary process graphics to take less space leaving room for additional information. However, these techniques were rejected, mainly because all parts of a process control screen need to be readable at all times. A new technique is proposed and its readability experimentally evaluated with promising results.

  • 277. Lindahl, L.
    et al.
    Odelstad, Jan
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap.
    Normative Systems and Their Revision: An Algebraic Approach2004In: Artificial Intelligence and Law, ISSN 0924-8463, E-ISSN 1572-8382, Vol. 11, no 2-3, p. 81-10Article in journal (Refereed)
    Abstract [en]

    The paper discusses normative systems and their revision within an algebraic framework. If a system is logically well-formed, certain norms, called connecting norms, determine the system as a whole. It is maintained that, if the system is well-formed, a relation "at least as low as" determines a lattice or quasi-lattice of its connecting norms. The ideas are presented mainly in the form of comments on a legal example concerning acquisition of movable property by extinction of another person's previous rights.

  • 278.
    Lindahl, Lars
    et al.
    Faculty of Law, University of Lund, Sweden.
    Odelstad, Jan
    University of Gävle, Department of Mathematics, Natural and Computer Sciences, Ämnesavdelningen för datavetenskap. DSV, KTH, Sweden.
    Intermediaries and intervenients in normative systems2008In: Journal of Applied Logic, ISSN 1570-8683, E-ISSN 1570-8691, Vol. 6, no 2, p. 229-250Article in journal (Refereed)
    Abstract [en]

    Many concepts in legal texts are "intermediaries", in the sense that they serve as links between statements of legal grounds, on one hand, and of legal consequences, on the other. In our paper, an algebraic representation of normative systems is used for distinguishing between different kinds of intermediaries and making the idea of a joining between grounds and consequences more precise. In Section 1, the idea of intermediaries is presented and earlier discussions of the subjects are outlined. In Section 2, we introduce the algebraic framework and develop the formal theory. After introducing our approach to the representation of a normative system, we here present a theory of "intervenients", seen as a tool for analysing intermediaries. In Section 3, dealing with applications, after presenting a model of the formal theory, suited for the analysis of concepts in normative systems, we apply the theory to a number of examples, introduced in the first part. Finally, in Section 4, we make some remarks on the methodology of intermediate concepts.

  • 279.
    Lindberg, Joakim
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Utredning av Mina sidor: en rekommendation för framtiden2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Funktionen Mina sidor ger medborgaren möjligheten att se och uträtta personliga ärenden på Gävle kommuns webbplats. Funktionen används idag i väldigt liten omfattning och Gävle kommun behöver svar på hur Mina sidor ska se ut och fungera i framtiden, om den överhuvudtaget är nödvändig. I den här studien har information om detta ämne samlats in med flera olika metoder. Inledningsvis gjordes en litteraturstudie som skapade en teoretisk bakgrund för kommande resultat. Sedan studerades Gävle kommuns webbplats, vilket gav en grundförståelse för nuläget och belyste en hel del problem. Vidare studerades 100 webbplatser kvantitativt för att ge en inblick i hur vanlig funktionen Mina sidor är och hur andra lösningar kan se ut. Till sist hölls tio kvalitativa intervjuer och ett fokusgruppsmöte med personer som har kunskap eller tankar kring detta område. Det resultat som den här datainsamlingen gett, presenteras i den här rapporten. På resultatet baseras fem rekommendationer för hur Gävle kommun bör arbeta med Mina sidor i framtiden.

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    exjobb_JLindberg_20110527
  • 280.
    Lindberg, Matthias
    University of Gävle, Department of Mathematics, Natural and Computer Sciences.
    Kundregisterbaserat kalkylprogram för lokal och serveransluten användning2008Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    Byggnadsautomation har i dagsläget ett kalkylprogram gjort i Excel som är helt fristående från deras kvalitetsprogram. Dom vill i och med detta få ett två delat system som användaren både ska kunna köra med eller utan anknytning till Internet. Programmet har tillgång till en befintlig kund och komponentregister som man kommer åt via en Web Service. Om det inte finns någon Internet uppkoppling så kommer dessa register att sparas lokalt för att sedan synkroniseras när det finns tillgång till Internet. En kalkyl ska kunna sparas och öppnas antingen på servern eller lokalt som i detta fall är en SQLite databas. Själva applikationen kommer att utvecklas i .NET miljö i C#.

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    FULLTEXT01
  • 281.
    Lindberg, Rebecca
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Computer and Geospatial Sciences, Computer Science.
    Kranse, Mattias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Computer and Geospatial Sciences, Computer Science.
    Tidsloggningssystem för ambulanshelikopterpiloter2019Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Active duty time is strictly regulated for ambulance helicopter pilots. Departures and arrivals are determined by incoming alarms, which can make active duty time calculations complicated. These calculations are currently done manually, which can generate uncertainty and unnecessary denial of incoming alarms as a result.

    In this work, a pilot study is made for a time management system for ambulance helicopter pilots, with the main purpose to decrease unnecessary denial of incoming alarms. An IT-system is created where a smartphone collects time data which in turn is presented in a web application.

    As a part of the system, the ability to automatically log flight time with a smartphone is explored. A smartphone application with the purpose of automatically logging flight time is made with its basis and ideas retrieved from previous research and data collection. The test result shows that the application logs the same flight time as the helicopter in 5 times out of 6, with the accuracy of one minute.

    For presenting the collected time data, a visualization model is made in the form of a web application based on previous research and established design principles. Testing of the visualization model shows, for the pilots, that it is easier to make an accurate decision under time pressure with the developed visualization model than with a numerical format of the same data. The result is analyzed with a t-test which concludes that the difference between the graphical and table presentation is statistically significant.

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    fulltext
  • 282.
    Lindeberg, Ronnie
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Utveckling av system för insamling och presentation av tryckskadeförekomster inom sjukvården2012Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    På sjukhuset i Gävle utförs regelbundet punktprevalensmätningar på uppkomsten av trycksår. Syftet med dessa mätningar är att hitta effektiva förebyggande åtgärder som kan användas för att minska uppkomsten av trycksår. Mätningarna utförs med hjälp av en surfplatta. För att underlätta insamlingen och presentationen av mätningarnas resultat har det utvecklats ett nytt datasystem. Datasystemet består av en databas med tillhörande databasapplikation. Applikationen är programmerad i Java och databashanteraren är ObjectDB. Datasystemet kan synkronisera och överföra data från surfplattans databas med en USB-kabel. Applikationen har ett användarvänligt grafiskt gränssnitt som ger en arbetsvänlig och enkel miljö att jobba i. Databasens innehåll kan presenteras på tre olika sätt, i en översiktstabell, i olika detaljtabeller och som ett linjediagram.

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    fulltext
  • 283.
    Lindgren, Jonathan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Tillämpningen och betydelsen av animationsprinciperna förmotion graphics design2014Independent thesis Basic level (degree of Bachelor), 180 HE creditsStudent thesis
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    Animationsprinciper_Avhandling_JonathanL
  • 284.
    Lindvall, Christer
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    iPacdesign2012Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Företaget Gepac Plast AB designar bärkassar till olika kunder och vill ha en tilltalande webbsida som fram häver deras arbetsområde. Samt en designfunktion på webbsidan som gör det möjligt för kunderna att skicka in egna designförslag för bärkassar till företaget. Med ett CMS system (Content Management System) för att bygga webbsidor ska de nya funktionerna till den existerande webbsidan skapas, med hjälp av plugin och ett dataprogram. Även en uppdatering av webbsidan ska utföras. Slutresultat för projektet fick blandat resultat med en lyckad uppdatering, medan den önskade designfunktionen inte är i bruk än så länge.

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    iPacdesign
  • 285.
    Lindén, Andreas
    et al.
    University of Gävle, Department of Mathematics, Natural and Computer Sciences.
    Söderström, Lars
    University of Gävle, Department of Mathematics, Natural and Computer Sciences.
    Tillit och säkerhet inom e-handel2006Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    Tillit och säkerhet är viktiga faktorer för att en användare ska vilja använda en e-handelsida. Det är mycket viktigt att visa att det finns en avsikt att bevara kundens personliga integritet. Genom att ha studerat olika artiklar som behandlar ämnet tillit har ett material samlats ihop som visar att säkerhet är en viktig fråga för de flesta användarna när en transaktion genomförs på Internet. Tidigare forskning har bland annat visat att konsumenter ogärna ändrar sina vanor, det som känns tryggt fortsätter man helst med, det finns ofta en ovilja att betala på nya sätt. Det har även visat sig att all information ska vara tydlig och lättillgänglig. Genom att använda oss av en abduktiv metod undersöker vi hur man skapar tillit. Som typfall användes en e-handelssida som skapades för det egna företaget LS Direkt, de tre grunderna som sidan byggdes efter var tillit, integritet och säkerhet. Resultatet blev en sida som uppfyllde dessa faktorer.

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    FULLTEXT01
  • 286.
    Liu, Dian
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Comparison Analysis of Color Constancy Algorithms2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Color constancy refers to a stable psychological tendency in perception even the lighting circumstances changed and it plays an important role in many computer vision applications. In this paper, an overview of many frequently used computational color constancy algorithms is presented. Besides, existing algorithms are usually divided into statistical and physics-based and we discuss the characteristic between them, and we also evaluate two main stream hypotheses that usually made before conducting the ill-posed Lambertian Reflectance Model and discuss about their different emphases. What’s more, we perform a comparison analysis in section 3 among three of the most basic algorithms with several well-defined criteria.

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    Thesis_DianLiu
  • 287.
    Liu, Fei
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Computer and Geospatial Sciences, Computer Science.
    Jonsson, Torsten
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Computer and Geospatial Sciences, Geospatial Sciences.
    Seipel, Stefan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Computer and Geospatial Sciences, Computer Science. Uppsala universitet.
    Evaluation of augmented reality-based building diagnostics using third person perspective2020In: ISPRS International Journal of Geo-Information, ISSN 2220-9964, Vol. 9, no 1, article id 53Article in journal (Other academic)
    Abstract [en]

    Comprehensive user evaluations of outdoor augmented reality (AR) applications in the architecture, engineering, construction and facilities management (AEC/FM) industry are rarely reported in the literature. This paper presents an AR prototype system for infrared thermographic façade inspection and its evaluation. The system employs markerless tracking based on image registration using natural features and a third person perspective (TPP) augmented view displayed on a hand-held smart device. We focus on evaluating the system in user experiments with the task of designating positions of heat spots on an actual façade as if acquired through thermographic inspection. User and system performance were both assessed with respect to target designation errors. The main findings of this study show that positioning accuracy using this system is adequate for objects of the size of one decimeter. After ruling out the system inherent errors, which mainly stem from our application-specific image registration procedure, we find that errors due to a human’s limited visual-motoric and cognitive performance, which have a more general implication for using TPP AR for target designation, are only a few centimeters.

  • 288.
    Liu, Fei
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Seipel, Stefan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Detection of Façade Regions in Street View Images from Split-and-Merge of Perspective Patches2014In: Journal of Image and Graphics, ISSN 2301-3699, Vol. 2, no 1, p. 8-14Article in journal (Refereed)
    Abstract [en]

    Identification of building façades from digital images is one of the central problems in mobile augmented reality (MAR) applications in the built environment. Directly analyzing the whole image can increase the difficulty of façade identification due to the presence of image portions which are not façade. This paper presents an automatic approach to façade region detection given a single street view image as a pre-processing step to subsequent steps of façade identification. We devise a coarse façade region detection method based on the observation that façades are image regions with repetitive patterns containing a large amount of vertical and horizontal line segments. Firstly, scan lines are constructed from vanishing points and center points of image line segments. Hue profiles along these lines are then analyzed and used to decompose the image into rectilinear patches with similar repetitive patterns. Finally, patches are merged into larger coherent regions and the main building façade region is chosen based on the occurrence of horizontal and vertical line segments within each of the merged regions. A validation of our method showed that on average façade regions are detected in conformity with manually segmented images as ground truth.

  • 289.
    Liu, Fei
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Seipel, Stefan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Detection of Line Features in Digital Images of Building Structures2012In: Proceedings of IADIS International Conference Computer Graphics, Visualization, Computer Vision and Image Processing 2012 (CGVCVIP 2012) / [ed] Yingcai Xiao, 2012, p. 163-167Conference paper (Refereed)
    Abstract [en]

    This paper describes method for detection of short line segments in digital images. It aims at identifying buildingsin images taken from the ground view. The process starts with the image edge map and is carried out in twodifferent levels. One is to detect long line segments usually stemming from façade edges and building silhouettes.The other one identifies shorter line segments which typically represent architectural details such as windows andentrances. Selected individual connected components in both vertical and horizontal gradient component mapsare used respectively as input to the Hough transform at this level. Our first result shows that this method iscapable of recognizing lines of interest but has also included many randomly oriented lines. The next step will beto eliminate the random line segments and correlate line segments of the two levels to classify high-level features ofbuildings in an image.

  • 290.
    Liu, Fei
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science. Centre for Image Analysis, Uppsala University, Uppsala, Sweden.
    Seipel, Stefan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science. Centre for Image Analysis, Uppsala University, Uppsala, Sweden.
    Infrared-visible image registration for augmented reality-based thermographic building diagnostics2015In: Visualization in Engineering, ISSN 2213-7459, Vol. 3, no 1, article id 16Article in journal (Refereed)
    Abstract [en]

    Background: In virtue of their capability to measure temperature, thermal infrared cameras have been widely used in building diagnostics for detecting heat loss, air leakage, water damage etc. However, the lack of visual details in thermal infrared images makes the complement of visible images a necessity. Therefore, it is often useful to register images of these two modalities for further inspection of architectures. Augmented reality (AR) technology, which supplements the real world with virtual objects, offers an ideal tool for presenting the combined results of thermal infrared and visible images. This paper addresses the problem of registering thermal infrared and visible façade images, which is essential towards developing an AR-based building diagnostics application. Methods: A novel quadrilateral feature is devised for this task, which models the shapes of commonly present façade elements, such as windows. The features result from grouping edge line segments with the help of image perspective information, namely, vanishing points. Our method adopts a forward selection algorithm to determine feature correspondences needed for estimating the transformation model. During the formation of the feature correspondence set, the correctness of selected feature correspondences at each step is verified by the quality of the resulting registration, which is based on the ratio of areas between the transformed features and the reference features. Results and conclusions: Quantitative evaluation of our method shows that registration errors are lower than errors reported in similar studies and registration performance is usable for most tasks in thermographic inspection of building façades.

  • 291.
    Liu, Fei
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science. Centre for Image Analysis, Uppsala University, Uppsala, Sweden.
    Seipel, Stefan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science. Centre for Image Analysis, Uppsala University.
    On the precision of third person perspective augmented reality for target designation tasks2017In: Multimedia tools and applications, ISSN 1380-7501, E-ISSN 1573-7721, Vol. 76, no 14, p. 15279-15296Article in journal (Refereed)
    Abstract [en]

    The availability of powerful consumer-level smart devices and off-the-shelf software frameworks has tremendously popularized augmented reality (AR) applications. However, since the built-in cameras typically have rather limited field of view, it is usually preferable to position AR tools built upon these devices at a distance when large objects need to be tracked for augmentation. This arrangement makes it difficult or even impossible to physically interact with the augmented object. One solution is to adopt third person perspective (TPP) with which the smart device shows in real time the object to be interacted with, the AR information and the user herself, all captured by a remote camera. Through mental transformation between the user-centric coordinate space and the coordinate system of the remote camera, the user can directly interact with objects in the real world. To evaluate user performance under this cognitively demanding situation, we developed such an experimental TPP AR system and conducted experiments which required subjects to make markings on a whiteboard according to virtual marks displayed by the AR system. The same markings were also made manually with a ruler. We measured the precision of the markings as well as the time to accomplish the task. Our results show that although the AR approach was on average around half a centimeter less precise than the manual measurement, it was approximately three times as fast as the manual counterpart. Additionally, we also found that subjects could quickly adapt to the mental transformation between the two coordinate systems.

  • 292.
    Liu, Fei
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science. Centre for Image Analysis, Uppsala University, Uppsala, Sweden.
    Seipel, Stefan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science. Centre for Image Analysis, Uppsala University, Uppsala, Sweden.
    Precision study on augmented reality-based visual guidance for facility management tasks2018In: Automation in Construction, ISSN 0926-5805, E-ISSN 1872-7891, Vol. 90, p. 79-90Article in journal (Refereed)
    Abstract [en]

    One unique capability of augmented reality (AR) is to visualize hidden objects as a virtual overlay on real occluding objects. This “X-ray vision” visualization metaphor has proved to be invaluable for operation and maintenance tasks such as locating utilities behind a wall. Locating virtual occluded objects requires users to estimate the closest projected positions of the virtual objects upon their real occluders, which is generally under the influence of a parallax effect. In this paper we studied the task of locating virtual pipes behind a real wall with “X-ray vision” and the goal is to establish relationships between task performance and spatial factors causing parallax through different forms of visual augmentation. We introduced and validated a laser-based target designation method which is generally useful for AR-based interaction with augmented objects beyond arm's reach. The main findings include that people can mentally compensate for the parallax error when extrapolating positions of virtual objects on the real surface given traditional 3D depth cues for spatial understanding. This capability is, however, unreliable especially in the presence of the increasing viewing offset between the users and the virtual objects as well as the increasing distance between the virtual objects and their occluders. Experiment results also show that positioning performance is greatly increased and unaffected by those factors if the AR support provides visual guides indicating the closest projected positions of virtual objects on the surfaces of their real occluders.

  • 293.
    Liu, Ran
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    A comparison of Ear Clipping and a new Polygon Triangulation Algorithm2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The simple polygon triangulation is an classic problem in computational geometry and the techniques are widely used in many field. Many existing techniques have short running time but are hard to implement, some are easy to achieve, however, the output quality always bad and are time consuming. This paper propose a diagonal inserting algorithm which is easy to implement and can enhance the final quality. This presented algorithm was implemented and compared with the ear clipping technique which is simple to carry out and long-standing in the triangulation history. These two algorithms were tested on various polygons and an analysis concerning the quality, speed and the standard deviation of the output triangles` size is done.

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    FULLTEXT02
  • 294.
    Liu, Xintao
    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.
    A novel approach to the identification of urban sprawl patches based on the scaling of geographic space2011In: International journal of Geomatics and Geosciences, ISSN 0976-4380, Vol. 2, no 2, p. 415-429Article in journal (Refereed)
    Abstract [en]

    This paper introduces a novel approach to identifying urban sprawl patches based on the statistics of blocks and natural cities under the principle of scaling of geographic space. Blocks are the minimum cycles decomposed from a road network and the important geographic elements in the process of urbanization. Scaling of geographic space refers to the phenomenon that small geographic objects are far more numerous than large ones. In this study, the measurements of block area, morphology and structure are found to demonstrate scaling property and follow heavy tailed distributions. Because of this, the mean values of these measurements can clearly divide all blocks into a two-level hierarchical structure, of which each hierarchy represents different geographical implications. For instance, small blocks imply the urban area while large ones imply rural area. Based on these findings, an improved method is proposed to aggregate the small blocks into natural cities in Texas. We further identify the abnormal blocks inside the natural city of Dallas, Texas as sprawling blocks, which constitute what we call urban sprawl patches. Multiple levels of urban sprawl are classified by performing the above process iteratively. This approach provides a quantitative and natural way to assess urban sprawl in the context of the urban environment.

  • 295.
    Liu, Xintao
    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.
    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.
    Defining and generating axial lines from street center lines for better understanding of urban morphologies2012In: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 26, no 8, p. 1521-1532Article in journal (Refereed)
    Abstract [en]

    Axial lines are defined as the longest visibility lines for representing individual linear spaces in urban environments. The least set of axial lines that cover the free space of an urban environment or the space between buildings constitute what is often called an axial map. This is a fundamental tool in space syntax, a theory developed by Bill Hillier and his colleagues for characterizing the underlying urban morphologies. For a long time, generating axial lines with the help of some graphic software has been a tedious manual process that is criticized for being time consuming, subjective, or even arbitrary. In this article, we redefine axial lines as the least set of individual straight line segments mutually intersected along natural streets that are generated from street center lines using the Gestalt principle of good continuity. Based on this new definition, we develop an automatic solution for generating the newly defined axial lines from street center lines. We apply this solution to six typical street networks (three from North America and three from Europe) and generate a new set of axial lines for analyzing the urban morphologies. Through a comparison study between the new axial lines and the conventional or old axial lines and between the new axial lines and natural streets, we demonstrate with empirical evidence that the newly defined axial lines are a better alternative for capturing the underlying urban structure.

  • 296.
    Liu, Xun
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Free Wind Path Detecting in Google Map Using Image Processing2010Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Urban heat island has become a serious environment problem in nowadays. One of the reasons is the buildings block the wind blow. For planning a scientific urban geometry to reduce the influence of urban heat island, one of the solutions is finding the free wind paths. There many previous works based on GIS, this paper will offer a new method found on image processing in digital map. Using MATLAB instead of GIS device, the algorithm provides a simple and easy-using way to detect the free wind paths in the eight directions.

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  • 297.
    Liu, Yu
    et al.
    Department of Systems Engineering and Engineering Management, City University of Hong Kong, Hong Kong, Hong Kong .
    Xie, Min
    Department of Systems Engineering and Engineering Management, City University of Hong Kong, Hong Kong, Hong Kong .
    Yang, Jianfeng
    Faculty of Information Engineering, Guizhou Institute of Technology, Guiyang, China .
    Zhao, Ming
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Industrial economics. University of Gävle, Center for Logistics and Innovative Production.
    A New Framework and Application of Software Reliability Estimation Based on Fault Detection and Correction Processes2015In: Proceedings: IEEE International Conference on Software Quality, Reliability and Security, QRS 2015, IEEE conference proceedings, 2015, p. 65-74, article id 7272916Conference paper (Refereed)
    Abstract [en]

    Software reliability growth modeling plays an important role in software reliability evaluation. To incorporate more information and provide more accurate analysis, modeling software fault detection and correction processes has attracted widespread research attention recently. However, the assumption of the stochastic fault correction time delay brings more difficulties in modeling and estimating the parameters. In practice, other than the grouped fault data, software test records often include some more detailed information, such as the rough time when one fault is detected or corrected. Such semi-grouped dataset contains more information about fault removal processes than commonly used grouped dataset. Using the semi-grouped datasets can improve the accuracy of time delayed models. In this paper, a fault removal modelling framework for software reliability with semi-grouped data is studied and extended into multi-released software. Also, the corresponding parameter estimation is carried out with Maximum Likelihood estimation method. One test dataset with three releases from a practical software project is applied with the proposed framework, which shows satisfactory performance with the results.

  • 298.
    Ljunggren, Lukas
    University of Gävle, Department of Mathematics, Natural and Computer Sciences.
    Recreation of Gävle after the Second Fire2007Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [en]

    In 1776, the City of Gävle was immersed in a blazing fire, almost the whole city burned down and buildings that managed to survived have either been demolished or replaced by another one. To provide an actual view of Gävle from 1800-century is difficult due to the three different fires. A three-dimensional visualization model presents the entire city between 1776-1815 as it might have appeared. Archival images and information was provided from Länsmusem Gävleborg, Fogden, City library of Gävle and the City Archive. The three-dimensional model of the entire city is presented in a QuickTime movie format for viewing.

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  • 299.
    Ludwigsson, Jonas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management.
    Creating realistic hair in Autodesk Maya2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This thesis work focuses on how to create realistic looking hair using only the vanilla version of Autodesk Maya. It describes two approaches, the widely used polygon-stripe based technique and the Maya built-in nHair. It also evaluates these two approaches in terms of ease of implementation, production speed and quality of final results. The conclusion is that nHair has the potential to produce realistic looking hair but contains various bugs and is not optimized at the current stage, while the polygon-stripe based approach is robust and flexible but the realism of rendering results is heavily dependent upon the skill level of artists.

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    Creating realistic hair in Autodesk Maya
  • 300.
    Lundberg, Anders
    University of Gävle, Department of Mathematics, Natural and Computer Sciences.
    Utvärdering av moderniseringsmetoder för användargränssnittet i ROS2008Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [sv]

    ROS är ett produktnära system som stödjer planering och återrapportering i stålverket. Sandvik vill undersöka möjligheterna att modernisera användargränssnittet på detta system som idag är terminalbaserat till ett modernt grafiskt interface. Två metoder analyseras, den ena innebär att använda en kommersiell produkt för screen scraping och den andra metoden är Web Services Integration Toolkit som är freeware. Resultatet från analysen visar att Web Services Integration Toolkit klarar av att uppfylla de mål som är satta. En testkörning av Web Services Integration Toolkit görs också på ROS och resultat visar att metoden fungerar även fungerar i praktiken.

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