hig.sePublications
Change search
Refine search result
12 51 - 81 of 81
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard-cite-them-right
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • sv-SE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • de-DE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 51. Sanders, Kate
    et al.
    Boustedt, Jonas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Eckerdal, Anna
    McCartney, Robert
    Moström, Jan Erik
    Thomas, Lynda
    Zander, Carol
    Threshold concepts and threshold skills in computing2012In: Proceedings of the ninth annual international conference on International computing education research, New York, NY, USA: Association for Computing Machinery (ACM), 2012, p. 23-30Conference paper (Refereed)
    Abstract [en]

    Threshold concepts can be used to both organize disciplinary knowledge and explain why students have difficulties at certain points in the curriculum. Threshold concepts transform a student's view of the discipline; before being learned, they can block a student's progress.

    In this paper, we propose that in computing, skills, in addition to concepts, can sometimes be thresholds. Some students report finding skills more difficult than concepts. We discuss some computing skills that may be thresholds and compare threshold skills and threshold concepts.

  • 52.
    Sanders, Kate
    et al.
    Rhode Island College, Providence, Rhode Island, USA.
    Boustedt, Jonas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Eckerdal, Anna
    Uppsala University, Uppsala, Sweden.
    McCartney, Robert
    University of Connecticut, Storrs, Connecticut, USA.
    Zander, Carol
    University of Washington, Bothell Bothell, Washington, USA.
    Folk Pedagogy: Nobody Doesn't Like Active Learning2017In: Proceedings of the 2017 ACM Conference on International Computing Education Research (ICER 17) / [ed] Josh Tenenberg and Lauri Malmi, Tacoma, Washington, USA: ACM Publications, 2017, p. 145-154Conference paper (Refereed)
    Abstract [en]

    In a survey of the computing education community, many respondents suggested "active learning" as a teaching approach that would increase the likelihood of student success. In light of these responses, we analyze the way in which active learning is described in the computing-education literature. We find a strong consensus that active learning is good, but a lack of precision in how the term is used, often without definition, to describe instructional techniques, rather than student learning. In addition, active learning techniques are often discussed as if they were all equally effective. We suggest that making clear distinctions, both between teaching techniques and active learning and among the teaching techniques, would be fruitful for both instructors and researchers. Finally, we propose some dimensions along which distinctions among techniques could usefully be made.

  • 53.
    Sandström, Oskar
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Voxlin, Viktor
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Centraliserad administration av Feature Toggles2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Vid kontinuerlig leverans samt långa utvecklingscykler av mjukvara exponeras system som fortfarande inte är färdigställda för användarna. Det ställer krav på att systemets funktionalitet antingen är brukbart eller otillgängligt. Denna utvecklingsparadigm inom den agila metodiken leder till att vissa funktioner behöver döljas för alla eller en viss del användare. Detta kan lösas med Feature Toggles som i sin tur kan skapa komplexitet och redundant källkod om de inte administreras via ett centraliserat system. Denna typ av administrativt verktyg finns i dagsläget endast tillgänglig via betallösningar. Målet med denna studie är att kvalitativt och kvantitativt undersöka tillvägagångssätt för utveckling av en sådan applikation. Genom en agil utvecklingsmetodik, användning av väl etablerade ramverk, bibliotek och standarder skapades ett administrativt system som möjliggör editering, spårning av händelser och sökfunktioner kopplat till Feature Toggles. Utöver denna funktionalitet skapades ett tillhörande Representional State Transfer – Application Programming Interface (REST-API) som bidrar till att konsumerande system kan ta del utav den centraliserade informationen. Vidare ämnar studien undersöka utvecklingsmöjligheter för applikationen vilket resulterade i ytterligare förslag till funktionalitet så som tidsinställda notifikationer om redundans, optimering av redan implementerad funktionalitet och användarautentisering för ökad säkerhet. Efter genomförda metoder uppnådde studien sitt syfte och resulterade i en applikation för administrering av Feature Toggles.

  • 54.
    Seipel, Stefan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science. Centre of Image Analysis, Uppsala University, Uppsala, Sweden.
    Evaluating 2D and 3D Geovisualizations for Basic Spatial Assessment2013In: Behavior and Information Technology, ISSN 0144-929X, E-ISSN 1362-3001, Vol. 32, no 8, p. 845-858Article in journal (Refereed)
    Abstract [en]

    This study investigates the use of 2D and 3D presentations of maps for the assessment of distances in a geographicalcontext. Different types of 3D representations have been studied: A weak 3D visualisation that provides staticmonocular depth cues and a strong 3D visualisation that uses stereoscopic and kinetic depth cues. Two controlledexperiments were conducted to test hypotheses regarding subjects’ efficiency in visually identifying the shortestdistance among a set of market locations in a map. As a general result, we found that participants were able tocorrectly identify shortest distances when the difference to potential alternatives was sufficiently large, butperformance decreased systematically when this difference decreased. Noticeable differences emerged for theinvestigated visualisation conditions. Participants in this study were equally efficient when using a weak 3Drepresentation and a 2D representation. When the strong 3D visualisation was employed, they reported visualdiscomfort and tasks were solved significantly less correct. Presentations of intrinsic 2D content (maps) in 3Dcontext did, in this study, not benefit from cues provided by a strong 3D visualisation and are adequatelyimplemented using a weak 3D visualisation.

  • 55.
    Seipel, Stefan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science. Uppsala universitet.
    Solving Geospatial Tasks in 2D and 3D Visualisation of Maps2014In: Information Visualisation: Techniques, Usability and Evaluation / [ed] Ebad Banissi, Francis T. Marchese, Camilla Forsell and Jimmy Johansson, Newcastle upon Tyne: Cambridge Scholars Publishing, 2014, 1, p. 222-271Chapter in book (Refereed)
  • 56.
    Seipel, Stefan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science. Centre of Image Analysis, Uppsala University.
    Carvalho, Leonor
    University of Turku.
    Solving Combined Geospatial Tasks Using 2D and 3D Bar Charts2012In: 2012 16th International Conference on Information Visualisation, 2012, p. 157-163Conference paper (Refereed)
    Abstract [en]

    This paper presents a user study that investigates2D and 3D visualizations of bar charts in geographic maps.The task to be solved by the participants in this studyrequired estimation of the ratio of two different spatial distancemeasures and relative ranking among potential candidates. Theresults of this experiment show that subjects were equally fastand accurate when using both the 2D and 3D visualizations.Visual discomfort was reported by almost half of the testpopulation, but performance was not affected. Our study alsoshowed that frequent game players did not benefit more froma 3D visualization than inexperienced game-players.

  • 57.
    Seipel, Stefan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Hast, Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    A Local Curvature Based Lighting Model for Rendering of Snow2010In: Proceedings of IADIS International Conference Computer Graphics, Visualization, Computer Vision and Image Processing 2010 (CGVCVIP 2010) / [ed] Yingcai Xiao, Tomaz Amon and Roberto Muffoletto, 2010, p. 367-372Conference paper (Refereed)
    Abstract [en]

    Local illumination models try to describe the interaction between light and objects in the scene based on only few parameters representing some geometric and material properties at a given point on a surface. In this paper we present our research in local illumination models for the purpose of approximating light transport and shadow-masking effects in the local neighborhood of the surface point under evaluation. We assume that the amount of curvature at a surface point to some extent represents geometric properties in the surrounding neighborhood of this point. From this we define an empirical illumination model for diffuse reflecting materials which controls the amount of locally scattered light from the neighborhood as well as subsurface light transport based on some curvature metric.

  • 58.
    Seipel, Stefan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Jenke, Peter
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Quantification of gaseous structures with volumetric reconstruction from visual hulls2011In: Proceedings of SIGRAD 2011. Evaluations of Graphics and Visualization, November 17–18, 2011, KTH, Stockholm, Sweden, 2011, p. 77-82Conference paper (Refereed)
    Abstract [en]

    3D reconstruction from visual hulls is a well established technique for camera based reconstruction of 3D objects in computer graphics. We propose in this paper to employ visual hull techniques to quantify the volume of diffusely defined gaseous structures. In our evaluation, visual quality of the 3D reconstructions is secondary. Instead, using synthetic ground truth data, we determine the number of independent silhouette images needed to achieve a stable volume estimate. We also estimate the influence of different segmentation results of the silhouette images on final volume estimates. Our results show that comparably few camera views yield to convergent volume estimates. For the type of 3D data studied, visual hull reconstructions overestimate actual volumes with about 50%. This proportion seems to be consistent for different data sets tested and may serve for re-calibration of volume estimation of gaseous structures.

  • 59.
    Seipel, Stefan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Lim, Nancy J.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Land management, GIS.
    Color map design for visualization in flood risk assessment2017In: International Journal of Geographical Information Science, ISSN 1365-8816, E-ISSN 1365-8824, Vol. 31, no 11, p. 2286-2309Article in journal (Refereed)
    Abstract [en]

    Visualizations of flood maps from simulation models are widely used for assessing the likelihood of flood hazards in spatial planning. The choice of a suitable type of visualization as well as efficient color maps is critical to avoid errors or bias when interpreting the data. Based on a review of previous flood uncertainty visualization techniques, this paper identifies areas of improvements and suggests criteria for the design of a task-specific color scale in flood map visualization. We contribute a novel color map design for visualizing probabilities and uncertainties from flood simulation ensembles. A user study encompassing 83 participants was carried out to evaluate the effects of this new color map on user’s decisions in a spatial planning task. We found that the type of visualization makes a difference when it comes to identification of non-hazardous sites in the flood risk map and when accepting risks in more uncertain areas. In comparison with two other existing visualization techniques, we observed that the new design was superior both in terms of task compliance and efficiency. In regions with uncertain flood statuses, users were biased toward accepting less risky locations with our new color map design.

  • 60.
    Seipel, Stefan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Lingfors, David
    Uppsala universitet.
    Widén, Joakim
    Uppsala universitet.
    Dual-Domain Visual Exploration of Urban Solar Potential2013In: Eurographics Workshop on Urban Data Modelling and Visualisation: UDMV 2013, May 6-10, 2013, Girona, Spain / [ed] Vincent Tourre and Gonzalo Besuievsky, 2013, p. 21-24Conference paper (Refereed)
    Abstract [en]

    Traditional methods for estimating the solar energy potential in buildings determine energy yields on an annual base and make use of highly aggregated geo-spatial data. This work proposes a method for detailed assessment of the potential solar energy yield in the temporal and spatial domain. Solar irradiance is evaluated using numerical methods based on hourly variation of solar irradiance and on actual building geometry. Results of our initial studies allow exploration of the variation patterns in solar yield depending on local and time-varying factors, which cannot be seen in coarse level solar planning tools. This helps identifying surfaces with good solar yield that are deemed unfavorable according to traditional planning practices.

  • 61.
    Seipel, Stefan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Liu, Fei
    Uppsala university.
    Ericsson, Martin
    Uppsala university.
    A curvature based lightning model for quasi-global diffuse illumination2010In: Proceedings of Eurographics 2010, Posters, 2010, p. poster5008--Conference paper (Refereed)
  • 62.
    Seipel, Stefan
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science. Department of Information Technology, Uppsala University, Uppsala, Sweden.
    Milutinovic, Goran
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Andrée, Martin
    Lantmäteriet, Gävle, Sweden.
    3D game technology in property formation2016In: 16th International Multidisciplinary Scientific GeoConference SGEM 2016: SGEM2016 Conference Proceedings : Book 2, 2016, p. 539-546Conference paper (Refereed)
    Abstract [en]

    The process of real property formation involves the analysis and assessment of legal documents and cadastral information available in digital form. Quite frequently, however, it is necessary to visit the sites to establish relevant information from the real land parcels as well as communicating with involved stakeholders in the natural environment, entailing substantial cost in terms of time and travel expenses. The objective of the work presented here is to investigate alternative, IT-based processes for property formation which draw on existing data and have the potential to substitute time- and cost-intensive field visits. More specifically, the presented study explores how 3D game-based technology can be used to facilitate virtual site visits as an alternative to physical field surveys. We approach this problem by suggesting a framework that enables interoperability of existing 3D terrain models from the national land survey as well as vector data from cadastral databases with existing gaming environments for interactive exploration. Following an analysis of the quality of the existing digital terrain data, we describe an alternative data-extraction pathway that is suitable for rendering of 3D terrain models in the game engine. We present some visual results of our 3D demo system which indicate that salient structures in the terrain relevant for assessment and establishing of property boundaries are readily accessible in the virtual environment. Results of a quantitative comparison of the tested data models also support what visual inspection suggests, that existing terrain data can be refined for use of virtual site visits for property formation.

  • 63.
    Sund, Pontus
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Kodanalys med mjukvarumetriker: En fältstudie hos Monitor ERP System AB2017Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Det finns inga definitiva överenskommelser om vad som är ”bra” programkod vilket gör det svårt att mäta kvaliteten hos programvara. Ändå är det viktigt för företag som säljer mjukvara att hålla hög kvalitet på koden för att underlätta ändringar när nya funktioner introduceras. Metriker kan användas för att mäta olika aspekter på objektorienterad design. Detta arbete undersöker (1) vilka metriker som är intressanta för Monitor ERP System AB, (2) vilka värden som är rekommenderade för dessa metriker, (3) vilka värden metrikerna producerar utifrån Monitors kodbas och (4) om värdena stämmer överens med framtagna rekommendationer. För att göra detta undersöks tidigare studier bland olika databaser, ett program skapas för att ta fram metrikvärdena och relativa gränsvärden genereras utifrån dessa. Till sist utförs en analys, där det visar sig att kodbasen till stor del följer rekommenderade gränsvärden.

  • 64.
    Tchamba, Junias
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Modelling the Potential Distribution of Golden Eagle Based on Maximum Entropy: The Experimental Cases of Sweden and Norway2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Species extinction is a major concern that affect all countries and continents. Norway and Sweden are not spared by these concerns. Therefore, several studies have led to creating a better understanding about the factors which contribute to the expansion of specific species such as the golden eagle among others. However, climate data such as the temperature and rainfall precipitation have not yet been considered as significant parameters. This study aims to experimentally investigate whether climate data can have an impact on the distribution of the threatened bird using maximum entropy modelling. In order to investigate such impact, climate data were acquired from a global climate data provider (worldclim) and the presence-only occurences of the studied bird downloaded from species data providers (www.gbif.org and www.artdatabanken.no). The results showed that the annual mean temperature was a shared factor in both Sweden and Norway. The maximum entropy modelling can be envisaged as an alternative or a complement to current techniques in GIS applications.

    Keywords: maximum entropy, golden eagle, species distribution, visualization, climate data.

  • 65.
    Thomas, Lynda
    et al.
    Aberystwyth University, Great Britain.
    Boustedt, Jonas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Eckerdal, Anna
    Uppsala University.
    McCartney, Robert
    University of Connecticut, USA.
    Moström, Jan-Erik
    Umeå University,.
    Sanders, Kate
    Rhode Island College, USA.
    Zander, Carol
    University of Washington, USA.
    A broader threshold: Including skills as well as concepts in computing education2014In: Threshold Concepts: From personal practice to communities of practice: Proceedings of the National Academy’s Sixth Annual Conference and the Fourth Biennial Threshold Concepts Conference / [ed] Catherine O´Mahony, Aril Buchanan,Mary O´Rourke, Bettie Higgs, Cork, Ireland: NAIRTL , 2014, p. 154-158Conference paper (Refereed)
    Abstract [en]

    We propose ‘threshold skills’ as a complement to threshold concepts. The definition of threshold concepts assumes that theoretical knowledge is paramount: gaining the understanding of particular concepts irreversibly transforms the learners.

    Mastering computing, like many disciplines, however, requires learning a combination of concepts and skills. Mathematicians learn to do proofs, musicians learn to play their instruments, and martial artists learn to make moves by doing these activities, not just intellectually understanding them. We propose some characteristics for threshold skills and outline implications for teaching and for future work.

  • 66.
    Thomas, Lynda
    et al.
    Computer Science, Aberystwyth University , UK.
    Boustedt, Jonas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Eckerdal, Anna
    Department of Information Technology, Uppsala University, Sweden.
    McCartney, Robert
    Department of Computer Science and Engineering University of Connecticut, USA.
    Moström, Jan-Erik
    Department of Computing Science, Umeå University , Sweden.
    Sanders, Kate
    Mathematics and Computer Science Department ,Rhode Island College, USA.
    Zander, Carol
    Computing & Software Systems, University of Washington Bothell , USA.
    In the liminal space: software design as a threshold skill2017In: Practice and Evidence of the Scholarship of Teaching and Learning in Higher Education, ISSN 1750-8428, E-ISSN 1750-8428, Vol. 12, no 2, p. 333-351Article in journal (Refereed)
    Abstract [en]

    In previous work we proposed the idea of ‘threshold skills’ as a complement to threshold concepts. The definition of threshold concepts assumes that theoretical knowledge is paramount: gaining the understanding of particular concepts irreversibly transforms the learners. We noted, however, that mastering computing, like many disciplines, requires learning a combination of concepts and skills, and we suggested that this required further investigation. In this paper we examine the activity of designing software as a possible example of such a threshold skill. We looked at 35 software designs collected from students nearing graduation in computing courses, and see many of the characteristics of threshold skill and also of students being in liminal space. A close examination of the students’ designs leads to some useful implications for teaching this fundamental activity.

  • 67. Thomas, Lynda
    et al.
    Boustedt, Jonas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Eckerdal, Anna
    McCartney, Robert
    Moström, Jan-Erik
    Sanders, Kate
    Zander, Carol
    Threshold concepts in computer science: an ongoing empirical investigation2010In: Threshold concepts and transformational learning / [ed] Jan H. F. Meyer, Ray Land, Caroline Baillie, Rotterdam: Sense Publishers , 2010, p. 241-258Chapter in book (Other academic)
    Abstract [en]

    The chapter describes an ongoing multi-national, multi-institutional project aimed at empirically identifying threshold concepts in Computer Science, and describing students’ experiences of learning these concepts.

  • 68.
    Wahlberg, David
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Data Reduction Methods for Deep Images2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Deep images for use in visual effects work during deep compositing tend to be

    very large. Quite often the files are larger than needed for their final purpose,

    which opens up an opportunity for optimizations. This research project is

    about finding methods for identifying redundant and excessive data use in

    deep images, and then approximate this data by resampling it and representing

    it using less data. Focus was on maintaining the final visual quality while

    optimizing the files so the methods can be used in a sharp production

    environment. While not being very successful processing geometric data, the

    results when optimizing volumetric data were very succesfull and over the

    expectations.

  • 69.
    Westergren, Sarah
    et al.
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Klang, Lars
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Begreppssamordning: En undersökande intervjustudie om terminologin inom geodataområdet2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 70.
    Yakob, Silvana
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Utvecklingsprocess av en mobilapplikation anpassad för KOL patienter2016Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Syftet med arbetet var att utveckla en programvara (app) för patienter med kroniskt obstruktiv lungsjukdom (KOL) för att de skall kunna lära känna sin sjukdom bättre och därmed förbättra sin livsstil för att kunna bromsa försämringen av sjukdomen. Åldersgruppen som appen vänder sig till är mellan 40-80 år och för att de äldre skall ta till sig den nya tekniken med smartphones bör appen ha en enkel design. Den här gruppen patienter har kanske inte så stor teknikvana med datorer så det är också en anledning att ha en app som är lätt att använda.Utvecklingsprocessen av appen har gjorts i flera steg. Först formulerades en rad frågor om hur appen skulle fungera. Därefter formulerades frågor som patienten skulle svara på. Den första versionen av appen var en Powerpointdesign som därefter utvecklades i olika steg till en färdig Android app. Flera patienter fick testa appen under utvecklingens gång och även svara på ett frågeformulär om deras upplevelse av att använda appen. Patienterna gav förslag på ändringar och uttryckte behov av utveckling. Slutversionen av appen blev omtyckt av testgruppen och några förslag har även lämnats till vidare utveckling.

  • 71.
    Zander, C.
    et al.
    Computing and Software Systems, University of Washington Bothell, Bothell, WA, United States .
    Boustedt, Jonas
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Eckerdal, A.
    Department of InformationTechnology, Uppsala University, Uppsala, Sweden .
    Mccartney, R.
    Department of Computer Science and Engineering, University of Connecticut, Storrs, CT, United States .
    Moström, J. E.
    Department of Computing Science, Umeå University, Umeå, Sweden .
    Sanders, K.
    Mathematics and Computer Science Department, Rhode Island College, Providence, RI, United States .
    Thomas, L.
    Department of Computer Science, Aberystwyth University, Aberystwyth, United Kingdom .
    Self-directed learning: Stories from industry2012In: Proceedings - 12th Koli Calling International Conference on Computing Education Research, Koli Calling 2012, 2012, p. 111-117Conference paper (Refereed)
    Abstract [en]

    We report preliminary results from an ongoing investigation of how computing professionals perceive and value selfdirected learning, based on a qualitative analysis of interviews with ten computing professionals. The professionals expect that future colleagues will have a well-developed ability to learn on their own. They indicate that professionals use a range of resources, strategies, and collaborators to help them learn. They find their work-related self-directed learning enjoyable, expressing a sense of confidence and pride; yet they often also find it to be a stressful never-ending process.

  • 72.
    Åhlén, Julia
    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. Uppsala University, Department of Information Technology, Sweden .
    Automatic water body extraction from remote sensing images using entropy2015In: Proceedings of the International Multidisciplinary Scientific GeoConference SGEM, 2015, Vol. 4, p. 517-524Conference paper (Refereed)
    Abstract [en]

    This research focuses on automatic extraction of river banks and other inland waters from remote sensing images. There are no up to date accessible databases of rivers and most of other waters objects for modelling purposes. The main reason for that is that some regions are hard to access with the traditional ground through techniques and thus the boundary of river banks are uncertain in many geographical positions. The other reason is the limitations of widely applied method for extraction of water bodies called normalized-difference water index (NDWI). There is a novel approach to extract water bodies, which is based on pixel level variability or entropy, however, the methods work somewhat satisfactory on high spatial resolution images, there is no verification of the method performance on moderate or low resolution images. Problems encounter identification of mixed water pixels and e.g. roads, which are built in attachment to river banks and thus can be classified as rivers. In this work we propose an automatic extraction of river banks using image entropy, combined with NDWI identification. In this study only moderate spatial resolution Landsat TM are tested. Areas of interest include both major river banks and inland lakes. Calculating entropy on such poor spatial resolution images will lead to misinterpretation of water bodies, which all exhibits the same small variation of pixel values as e.g. some open or urban areas. Image entropy thus is calculated with the modification that involves the incorporation of local normalization index or variability coefficient. NDWI will produce an image where clear water exhibits large difference comparing to other land features. We are presenting an algorithm that uses an NDWI prior to entropy processing, so that bands used to calculate it, are chosen in clear connection to water body features that are clearly discernible.As a result we visualize a clear segmentation of the water bodies from the remote sensing images and verify the coordinates with a given geographic reference.

  • 73.
    Åhlén, Julia
    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.
    Seipel, Stefan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Early Recognition of Smoke in Digital Video2010In: Advances in Communications, Computers, Systems, Circuits and Devices: European Conference of Systems, ECS'10, European Conference of Circuits Technology and Devices, ECCTD'10, European Conference of Communications, ECCOM'10, ECCS'10 / [ed] Mladenov, V; Psarris, K; Mastorakis, N; Caballero, A; Vachtsevanos, G, Athens: World Scientific and Engineering Academy and Society, 2010, p. 301-306Conference paper (Refereed)
    Abstract [en]

    This paper presents a method for direct smoke detection from video without enhancement pre-processing steps. Smoke is characterized by transparency, gray color and irregularities in motion, which are hard to describe with the basic image features. A method for robust smoke description using a color balancing algorithm and turbulence calculation is presented in this work. Background extraction is used as a first step in processing. All moving objects are candidates for smoke. We make use of Gray World algorithm and compare the results with the original video sequence in order to extract image features within some particular gray scale interval. As a last step we calculate shape complexity of turbulent phenomena and apply it to the incoming video stream. As a result we extract only smoke from the video. Features such shadows, illumination changes and people will not be mistaken for smoke by the algorithm. This method gives an early indication of smoke in the observed scene.

  • 74.
    Åhlén, Julia
    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.
    Seipel, Stefan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Indication of Methane Gas in IR-Imagery2011In: Proceedings of IADIS International Conference Computer Graphics, Visualization, Computer Vision and Image Processing 2011, 2011, p. 187-192Conference paper (Refereed)
    Abstract [en]

    There are human produced sources of methane gas, such as waste storages, that contribute to the global warmth and other negative effects. There is not much research on the correlation of such leakage and greenhouse effect. Methane gas is not visible for humans and thus impossible to detect using commercial cameras. Specially designed IR-camera can detect this gas and thus is used in this study. Using digital video taken over a waste disposal place we create a detection algorithm that is sensitive to the spectral and morphological characteristics of methane gas. Different kind of leakage can take place in waste disposal places. In case of small spot leakage there is a reason to assume failure in piping system and in case of widely spread leakage area we can state that it is caused by unsupervised storage of waste and this should be attended immediately. In digital video, background and target gas are distinguished using spectral and morphological classifiers, which are extracted from the analyzed IR-imagery. It is shown that indications of methane gas can be carried out efficiently using image processing techniques and the definition of turbulence of the image.

  • 75.
    Åhlén, Julia
    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.
    Seipel, Stefan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Knowledge Based Single Building Extraction and Recognition2014In: Recent Advances in Computer Engineering, Communications and Information Technology / [ed] Josip Music, WSEAS Press , 2014, p. 29-35Conference paper (Refereed)
    Abstract [en]

    Building facade extraction is the primary step in the recognition process in outdoor scenes. It is also a challenging task since each building can be viewed from different angles or under different lighting conditions. In outdoor imagery, regions, such as sky, trees, pavement cause interference for a successful building facade recognition. In this paper we propose a knowledge based approach to automatically segment out the whole facade or major parts of the facade from outdoor scene. The found building regions are then subjected to recognition process. The system is composed of two modules: segmentation of building facades region module and facade recognition module. In the facade segmentation module, color processing and objects position coordinates are used. In the facade recognition module, Chamfer metrics are applied. In real time recognition scenario, the image with a building is first analyzed in order to extract the facade region, which is then compared to a database with feature descriptors in order to find a match. The results show that the recognition rate is dependent on a precision of building extraction part, which in turn, depends on a homogeneity of colors of facades.

  • 76.
    Åhlén, Julia
    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. Uppsala University, Department of Information Technology, Sweden.
    Mapping of roof types in orthophotos using feature descriptors2018In: International Multidisciplinary Scientific GeoConference Surveying Geology and Mining Ecology Management, SGEM: Proceedings of the International Multidisciplinary Scientific GeoConference SGEM, 2018, Vol. 18, p. 285-291Conference paper (Refereed)
    Abstract [en]

    In the context of urban planning, it is very important to estimate the nature of the roof of every building and, in particular, to make the difference between flat roofs and gable ones. This analysis is necessary in seismically active areas. Also in the assessment of renewable energy projects such solar energy, the shape of roofs must be accurately retrieved. In order to perform this task automatically on a large scale, aerial photos provide a useful solution. The goal of this research project is the development of algorithm for accurate mapping of two different roof types in digital aerial images. The algorithm proposed in this paper includes several components: pre-processing step to reduce illumination differences of individual roof surfaces, statistical moments calculation and color indexing. Roof models are created and saved as masks with feature specific descriptors. Masks are then used to mark areas that contain elements of the different roof types (e.g. gable and hip). The final orthophoto visualize an accurate position of each of the roof types. The result is evaluated using precision recall method.

  • 77.
    Åhlén, Julia
    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. Department of Information Technology, Uppsala University, Uppsala, Sweden.
    Segmentation of shadows and water bodies in high resolution images using ancillary data2016In: 16th International Multidisciplinary Scientific GeoConference SGEM 2016: SGEM2016 Conference Proceedings : Book 2, 2016, Vol. 1, p. 827-834Conference paper (Refereed)
    Abstract [en]

    High spatial resolution imagery is often affected by shadows, both in urban environments with large variations in surface elevation and in vegetated areas. It is a common bias in classification when waters and shadows are registered as the same area. The radiometric response for the shadowed regions should be restored prior to classification. To enable that, separate classes of non-shadowed regions and shadowed areas should be created. Previous work on water extraction using low/medium resolution images, mainly faced two difficulties. Firstly, it is difficult to obtain accurate position of water boundary and secondly, shadows of elevated objects e.g. buildings, bridges, towers and trees are a typical source of noise when facing water extraction in urban regions. In high resolution images the problem of separation water and shadows becomes more prominent since the small local variation of intensity values gives rise to misclassification. This paper proposes a robust method for separation of shadowed areas and water bodies in high spatial resolution imagery using hierarchical method on different scales combined with classification of PCA (Principal Component Analysis) bands, which reduces the effects of radiometric and spatial differences that is commonly associated with the pixel-based methods for multisource data fusion. The method uses ancillary data to aid in classification of shadows and waters. The proposed method includes three steps: segmentation, classification and postprocessing. To achieve robust segmentation, we apply the merging region with three features (PCA bands, NSVDI (Normalized Saturation-value Difference Index) and height data). NSVDI discriminates shadows and some water. In the second step we use hierarchic region based classification to identify water regions. After that step candidates for water pixels are verified by the LiDAR DEM data. As a last step we consider shape parameters such as compactness and symmetry to completely remove shadows.

  • 78.
    Åhlén, Julia
    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.
    Seipel, Stefan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Time-space visualisation of Amur river channel changes due to flooding disaster2014In: Proceedings of the International Multidisciplinary Scientific GeoConference SGEM, 2014, Vol. 1:2, p. 873-882Conference paper (Refereed)
    Abstract [en]

    The analysis of flooding levels is a highly complex temporal and spatial assessment task that involves estimation of distances between references in geographical space as well as estimations of instances along the time-line that coincide with  given spatial locations. This work has an aim to interactively explore changes of Amur River boundaries caused by the severe flooding in September 2013. In our analysis of river bank changes we use satellite imagery (Landsat 7) to extract parts belonging to Amur River. We use imagery from that covers time interval July 2003 until February 2014. Image data is pre-processed using low level image processing techniques prior to visualization. Pre-processing has a purpose to extract information about the boundaries of the river, and to transform it into a vectorized format, suitable as inputs subsequent visualization. We develop visualization tools to explore the spatial and temporal relationship in the change of river banks. In particular the visualization shall allow for exploring specific geographic locations and their proximity to the river/floods at arbitrary times. We propose a time space visualization that emanates from edge detection, morphological operations and boundary statistics on Landsat 2D imagery in order to extract the borders of Amur River. For the visualization we use the time-space-cube metaphor. It is based on a 3D rectilinear context, where the 2D geographical coordinate system is extended with a time-axis pointing along the 3rd Cartesian axis. Such visualization facilitates analysis of the channel shape of Amur River and thus enabling for a conclusion regarding the defined problem. As a result we demonstrate our time-space visualization for river Amur and using some amount of geographical point data as a reference we suggest an adequate method of interpolation or imputation that can be employed to estimate value at a given location and time.   

  • 79.
    Åhlén, Julia
    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. Uppsala University, Department of Information Technology, Sweden.
    Kautz, Marie-Loise
    Technische Universität, Dresden, Germany.
    Data source evaluation for shoreline deliniation applications2017In: International Multidisciplinary Scientific GeoConference Surveying Geology and Mining Ecology Management, SGEM: Conference proceedings, 2017, Vol. 17, no 2-3, p. 849-858Conference paper (Refereed)
    Abstract [en]

    This paper proposes an evaluation of data acquired with various sensors and used in coastal water segmentation applications. Correct monitoring of coastal changes in dynamic coastal environments strongly depends on accurate and frequent detection of shoreline position. Automatic shoreline delineation methods are preferable, especially in terms of time, cost, labor intensiveness and difficulties of in-situ measurements. Two main issues have been encountered within this application field, the quality of data and the segmentation algorithms. In this work, potential benefits of various data sources including optical and active sensors for extraction of shorelines have been investigated. The goal with shoreline detection from digital data sources is to obtain information as efficiently as possible and as reliably as necessary. Starting with that observation the paper discusses the effectiveness of coastal information extraction provided different data sources. This question is especially important to address since we observe a fast development of high spatial resolution data acquisition. There are many of segmentation algorithms described in the field of image processing and yet there is currently no single theory or method, no universal segmentation framework, that can be applied on all images to precisely and robustly extract shorelines. Nether there is a uniform standard for the assessment of segmentation results, and this process still largely relies on visual analysis and personal judgment. Out of myriads of image segmentation algorithms, we chose the most frequently and successfully applied within the application field and considering the data sources. In optical sensor data cases, the most frequently used methods are NDWI (Normalized Difference Water Index) and thresholding techniques. We do not aim to create yet another method to segment out the particular objects from remotely sensed data and then tailor it to work efficiently on that data set. Instead, we evaluate the data quality regarding the given application field. The case study is carried out on a 10 km coastal stretch facing the Baltic Sea (Sweden) and belonging to the Municipality of Gävle. In citu measurements were acquired to evaluate the extracted coastal lines and comparisons with reference were performed based on the average mean distance. A conclusion is done regarding the most reliable data source for this particular application of shoreline delineation.

  • 80.
    Åhlén, Julia
    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.
    Seipel, Stefan
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Liu, Fei
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Evaluation of the Automatic methods for Building Extraction2014In: International Journal Of Computers and Communications, ISSN 2074-1294, Vol. 8, p. 171-176Article in journal (Refereed)
    Abstract [en]

    Recognition of buildings is not a trivial task, yet highly demanded in many applications including augmented reality for mobile phones. Recognition rate can be increased significantly if building façade extraction will take place prior to the recognitionprocess. It is also a challenging task since eachbuilding can be viewed from different angles or under differentlighting conditions. Natural situation outdoor is when buildings are occluded by trees, street signs and other objects. This interferes for successful building façade recognition. In this paper we evaluate the knowledge based approach  to automatically segment out the whole buildingfaçade or major parts of thefaçade. This automatic building detection algorithm is then evaluated against other segmentation methods such as SIFT and vanishing point approach. This work contains two main steps: segmentation of building façades region using two different approaches and evaluation of the methods using database of reference features. Building recognition model (BRM) includes evaluation step that uses Chamfer metrics. BMR is then compared to vanishing points segmentation. In the evaluation mode, comparison of these two different segmentation methods is done using the data from ZuBuD.Reference matching is also done using Scale Invariant Feature Transform. Theresults show that the recognition rate is satisfactory for the BMR model and there is no need to extract the whole building façade for the successful recognition.

  • 81.
    Östberg, Rasmus
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Industrial Development, IT and Land Management, Computer science.
    Robustness of a neural network used for image classification: The effect of applying distortions on adversarial examples2018Independent thesis Basic level (professional degree), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Powerful classifiers as neural networks have long been used to recognise images; these images might depict objects like animals, people or plain text. Distorted images affect the neural network's ability to recognise them, they might be distorted or changed due to distortions related to the camera.Camera related distortions, and how they affect the accuracy, have previously been explored. Recently, it has been proven that images can be intentionally made harder to recognise, an effect that last even after they have been photographed.Such images are known as adversarial examples.The purpose of this thesis is to evaluate how well a neural network can recognise adversarial examples which are also distorted. To evaluate the network, the adversarial examples are distorted in different ways and thereafter fed to the neural network.Different kinds of distortions (rotation, blur, contrast and skew) were used to distort the examples. For each type and strength of distortion the network's ability to classify was measured.Here, it is shown that all distortions influenced the neural network's ability to recognise images.It is concluded that the type and strength of a distortion are important factors when classifying distorted adversarial examples, but also that some distortions, rotation and skew, are able to keep their characteristic influence on the accuracy, even if they are influenced by other distortions.

12 51 - 81 of 81
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard-cite-them-right
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • sv-SE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • de-DE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf