| 1. |
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| 2. |
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| 3. |
- Jensen, N., et al.
(författare)
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CoVASE: Collaborative Visualization for Constructivist Learning
- 2003
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Ingår i: Computer Support for Collaborative Learning 2003.
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Konferensbidrag (refereegranskat)abstract
- The paper specifies CoVASE, a software for teachers to create and view networked learning environments (VE). Students carry out virtual experiments in CoVASE, at the same time and different places. They use the same tools and work on the same scientific p
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| 4. |
- Jensen, N, et al.
(författare)
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Development of a Virtual Laboratory System for Science Education and the Study of Collaborative Action
- 2004
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Ingår i: Proceedings of AACE ED Media Conference 2004. - 1880094533
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The paper specifies the development of a toolkit to run synthetic science laboratories. The aim was to facilitate collaborative experimenting for problem-based learning in a virtual lab. The goal was to demonstrate virtual experimenting by use of interactive 3D visualization and simulation. Technology was developed over six years and in part designed in explicit accordance to didactic models. For tests, we built a virtual lab that comprised media tools and complex computer simulations, and we evaluated it with promising results. Students used data from meteorology and experimented together. Generally, they enjoyed using the system and collaborated in a motivated way. We identified which tools they preferred. The paper indicates ways to improve the design of virtual labs by use of our toolkit.
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| 5. |
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| 6. |
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| 7. |
- Koch, S, et al.
(författare)
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Controlled diagnosis-oriented enhancement of automatically segmented radiographs in dentistry
- 1998
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Ingår i: COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE. - : ELSEVIER SCI IRELAND LTD. - 0169-2607. ; 57:1-2, s. 125-131
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Tidskriftsartikel (refereegranskat)abstract
- A method for controlled diagnosis-oriented enhancement of selected regions of interest in intraoral radiographs is presented. Image enhancement is accomplished by adaptive non-linear grey scale transformation depending on the result of objective quality m
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| 8. |
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| 9. |
- Koch, S, et al.
(författare)
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IT-based evaluation and automatic improvement of the quality of intraoral radiographs
- 1995
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Ingår i: COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE. - : ELSEVIER SCI PUBL IRELAND LTD. - 0169-2607. ; 46:1, s. 41-50
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Tidskriftsartikel (refereegranskat)abstract
- The quality of intraoral radiographs made in dental practices is too often not adequate for diagnostic purposes. This necessitates standardized measures for the quality of intraoral radiographs and controlled techniques for automatic image improvement. Fo
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| 10. |
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| 11. |
- Lembrechts, Jonas J., et al.
(författare)
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SoilTemp : A global database of near-surface temperature
- 2020
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 26:11, s. 6616-6629
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Tidskriftsartikel (refereegranskat)abstract
- Current analyses and predictions of spatially explicit patterns and processes in ecology most often rely on climate data interpolated from standardized weather stations. This interpolated climate data represents long-term average thermal conditions at coarse spatial resolutions only. Hence, many climate-forcing factors that operate at fine spatiotemporal resolutions are overlooked. This is particularly important in relation to effects of observation height (e.g. vegetation, snow and soil characteristics) and in habitats varying in their exposure to radiation, moisture and wind (e.g. topography, radiative forcing or cold-air pooling). Since organisms living close to the ground relate more strongly to these microclimatic conditions than to free-air temperatures, microclimatic ground and near-surface data are needed to provide realistic forecasts of the fate of such organisms under anthropogenic climate change, as well as of the functioning of the ecosystems they live in. To fill this critical gap, we highlight a call for temperature time series submissions to SoilTemp, a geospatial database initiative compiling soil and near-surface temperature data from all over the world. Currently, this database contains time series from 7,538 temperature sensors from 51 countries across all key biomes. The database will pave the way toward an improved global understanding of microclimate and bridge the gap between the available climate data and the climate at fine spatiotemporal resolutions relevant to most organisms and ecosystem processes.
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| 12. |
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| 13. |
- Seipel, S, et al.
(författare)
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Oral implant treatment planning in a virtual reality environment
- 1998
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Ingår i: COMPUTER METHODS AND PROGRAMS IN BIOMEDICINE. - : ELSEVIER SCI IRELAND LTD. - 0169-2607. ; 57:1-2, s. 95-103
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Tidskriftsartikel (refereegranskat)abstract
- A system for three-dimensional oral implant treatment planning is presented. Virtual reality technologies are used in order to improve the human image interpretation and planning performance. The methods described are based on computer tomography (CT) dat
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| 19. |
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| 20. |
- Aslani, Mohammad
(författare)
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Computational and spatial analyses of rooftops for urban solar energy planning
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In cities where land availability is limited, rooftop photovoltaic panels (RPVs) offer high potential for satisfying concentrated urban energy demand by using only rooftop areas. However, accurate estimation of RPVs potential in relation to their spatial distribution is indispensable for successful energy planning. Classification, plane segmentation, and spatial analysis are three important aspects in this context. Classification enables extracting rooftops and allows for estimating solar energy potential based on existing training samples. Plane segmentation helps to characterize rooftops by extracting their planar patches. Additionally, spatial analyses enable the identification of rooftop utilizable areas for placing RPVs. This dissertation aims to address some issues associated with these three aspects, particularly (a) training support vector machines (SVMs) in large datasets, (b) plane segmentation of rooftops, and (c) identification of utilizable areas for RPVs. SVMs are among the most potent classifiers and have a solid theoretical foundation. However, they have high time complexity in their training phase, making them inapplicable in large datasets. Two new instance selection methods were proposed to accelerate the training phase of SVMs. The methods are based on locality-sensitive hashing and are capable of handling large datasets. As an application, they were incorporated into a rooftop extraction procedure, followed by plane segmentation. Plane segmentation of rooftops for the purpose of solar energy potential estimation should have a low risk of overlooking superstructures, which play an essential role in the placement of RPVs. Two new methods for plane segmentation in high-resolution digital surface models were thus developed. They have an acceptable level of accuracy and can successfully extract planar segments by considering superstructures. Not all areas of planar segments are utilizable for mounting RPVs, and some factors may further limit their useability. Two spatial methods for identifying RPV-utilizable areas were developed in this realm. They scrutinize extracted planar segments by considering panel installation regulations, solar irradiation, roof geometry, and occlusion, which are necessary for a realistic assessment of RPVs potential. All six proposed methods in this thesis were thoroughly evaluated, and the experimental results show that they can successfully achieve the objectives for which they were designed.
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| 21. |
- Jensen, N, et al.
(författare)
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CoVASE - Collaborative Visualization for Constructivist Learning
- 2003
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Ingår i: Designing for Change in Networked Learning Environments. ; , s. 249-253
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The paper specifies CoVASE, a software for teachers to create and view networked learning environments (VE). Students carry out virtual experiments in CoVASE, at the same time and from different places. They use the same tools and work on the same scientific problems as researchers do. Teachers create a motivating, demanding, and authentic interaction between learners and real-world problems, a premise for constructivist learning (CL). CoVASE generates and displays the result of a numerical simulation in parallel of its progress on distributed 3D graphic viewers, steered by users in real-time. VEs mediate communication between users, deictic elements, and display. Researchers and students have evaluated the predecessors of CoVASE with good results. A field study is planned for 2003.
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| 22. |
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| 23. |
- Lim, Nancy Joy, 1980-
(författare)
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Modelling, mapping and visualisation of flood inundation uncertainties
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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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| 24. |
- Lim, Nancy Joy, 1980-, et al.
(författare)
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Visualisation and evaluation of flood uncertainties based on ensemble modelling
- 2016
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Ingår i: International Journal of Geographical Information Science. - : Taylor & Francis. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 30:2, s. 240-262
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Tidskriftsartikel (refereegranskat)abstract
- 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.
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| 25. |
- Ma, Lei, Doktorand, et al.
(författare)
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Simple agents - complex emergent path systems : Agent-based modelling of pedestrian movement
- 2024
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Ingår i: Environment and planning B: Urban analytics and city science. - : Sage Publications. - 2399-8083 .- 2399-8091. ; 51:2, s. 479-495
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Tidskriftsartikel (refereegranskat)abstract
- In well-planned open and semi-open urban areas, it is common to observe desire paths on the ground, which shows how pedestrians themselves enhance the walkability and affordance of road systems. To better understand how these paths are formed, we present an agent-based modelling approach that simulates real pedestrian movement to generate complex path systems. By using heterogeneous ground affordance and visit frequency of hotspots as environmental settings and by modelling pedestrians as agents, path systems emerge from collective interactions between agents and their environment. Our model employs two visual parameters, angle and depth of vision, and two guiding principles, global conception and local adaptation. To examine the model’s visual parameters and their effects on the cost-efficiency of the emergent path systems, we conducted a randomly generated simulation and validated the model using desire paths observed in real scenarios. The results show that (1) the angle (found to be limited to a narrow range of 90–120°) has a more significant impact on path patterns than the depth of vision, which aligns with Space Syntax theories that also emphasize the importance of angle for modelling pedestrian movement; (2) the depth of vision is closely related to the scale-invariance of path patterns on different map scales; and (3) the angle has a negative exponential correlation with path efficiency and a positive correlation with path costs. Our proposed model can help urban planners predict or generate cost-efficient path installations in well- and poorly designed urban areas and may inspire further approaches rooted in generative science for future cities.
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| 26. |
- Ma, Lei, Doktorand, et al.
(författare)
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Simple agents – complex emergent path systems: Agent-based modelling of pedestrian movement
- 2024
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Ingår i: Environment and Planning B: Urban Analytics and City Science. - : Sage Publications. - 2399-8083 .- 2399-8091. ; 51:2, s. 479-495
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Tidskriftsartikel (refereegranskat)abstract
- In well-planned open and semi-open urban areas, it is common to observe desire paths on the ground, which shows how pedestrians themselves enhance the walkability and affordance of road systems. To better understand how these paths are formed, we present an agent-based modelling approach that simulates real pedestrian movement to generate complex path systems. By using heterogeneous ground affordance and visit frequency of hotspots as environmental settings and by modelling pedestrians as agents, path systems emerge from collective interactions between agents and their environment. Our model employs two visual parameters, angle and depth of vision, and two guiding principles, global conception and local adaptation. To examine the model’s visual parameters and their effects on the cost-efficiency of the emergent path systems, we conducted a randomly generated simulation and validated the model using desire paths observed in real scenarios. The results show that (1) the angle (found to be limited to a narrow range of 90–120°) has a more significant impact on path patterns than the depth of vision, which aligns with Space Syntaxtheories that also emphasize the importance of angle for modelling pedestrian movement; (2) the depth of vision is closely related to the scale-invariance of path patterns on different map scales; and(3) the angle has a negative exponential correlation with path efficiency and a positive correlation with path costs. Our proposed model can help urban planners predict or generate cost-efficient path installations in well- and poorly designed urban areas and may inspire further approaches rooted in generative science for future cities.
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| 27. |
- Milutinovic, Goran
(författare)
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Computational and Visual Tools for Geospatial Multi-Criteria Decision-Making
- 2020
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Geospatial multi-criteria decision-making usually concerns quasi-continuous choice models, with the number of alternatives constrained only by the limits of the used representation model. This sets high demands on the decision-making methods used in the context. The most commonly used approach in geospatial decision-making is combining a method for assigning criteria weights with an aggregation method. As pairwise comparison of alternatives is not feasible when the number of alternatives is large, the weights are usually assigned to criteria without considering the values or the value ranges of the alternatives, an approach often criticized in the decision analysis literature. Apart from criteria weighting controversy, this approach does not allow for advanced use of interactive visualization in the choice phase of the decision-making process. In this thesis, two alternative methods for geospatial decision-making based on the even swaps method are developed. The first method relies on automation of swaps, which makes this method viable for decision problems with any number of alternatives. The second method emanates from the findings of behavioral decision theory, and combines even swaps with reduction of large data sets through quasi-satisficing, allowing for efficient use of interactive visualization in the choice phase of the decision process. Visualization frameworks for both methods are also developed in the thesis. They include both geo-specific representations, such as interactive maps, and infovis techniques such as graphs, diagrams, scatterplots and parallel coordinates. Two studies concerning the impact of interactive visualization on decision-making are presented in the thesis: a study concerning the impact of interactive visualization on geospatial decision-making, and a study concerning potential effects of visual saliency on decision-making. The results of the first study indicated positive effects of interactive visualization on coherency and consistency in performing trade-offs. The results of the second study show that visual saliency may help decision-makers make better decisions. The work presented in this thesis contributes to method development and the use of interactive visualization in the context of geospatial decision-making.
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| 28. |
- Milutinovic, Goran, et al.
(författare)
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The impact of interactive visualization on trade-off-based geospatial decision-making
- 2019
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Ingår i: International Journal of Geographical Information Science. - : Taylor & Francis. - 1365-8816 .- 1365-8824 .- 1362-3087. ; 33:10, s. 2094-2123
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Tidskriftsartikel (refereegranskat)abstract
- In a previous work we developed GISwaps, a novel method for geospatial decision-making based on Even Swaps. In this paper, we present the results of an evaluation of a visualization framework integrated with this method, implemented within a decision support system. This evaluation is based on two different studies. In the quantitative study, 15 student participants used GISwaps with no visual features, and 15 participants used GISwaps with the integrated visual framework, as the tool in a solar farm site location case study. The results of the quantitative evaluation show positive impact of the visualization in terms of increased coherency in trade-offs. The results also show a statistically significant difference in average trade-off values between the groups, with users from the non-visual group setting on average 20% higher trade-off values compared with the users in the visual group. In the qualitative study, we had one expert in GIS, two experts in decision-making and two experts in solar energy as a focus user group. Data in this study were obtained by observations and semi-structured interviews with the participants. The impact of the visualization framework was assessed positively by all participants in the expert group.
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| 29. |
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| 31. |
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| 32. |
- Seipel, S., et al.
(författare)
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Methods and application of interactive 3D computer graphics in anthropology
- 2002
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report presents 3D computer graphics techniques for interactive visual exploration of virtual mummies. It is part of an exposition on the Cultural Heritage of the Egyptian Mummies in the Museum Gustavianum, in Uppsala. We describe a general-purpose projection metaphor for correctly presenting virtual 3D images on the dissection table of a historical anatomic theatre. This method allows for dynamic off-axis perspective viewing situations as well as it provides keystone correction for excessive projection angles as necessitated by the specific installation environment. For the application to reach out beyond the scope of the exhibition, we developed an adaptive image-based rendering approach that scales with the performance of the rendering host. Based on dynamic mesh simplification of the 3D mummy model, it automatically performs re-projections of texture images in order to maintain correct visual results. For interaction purposes with a digitiser tablet we present a means of stroke-based input that provides ease of use to non-expert visitors of the exhibition. The problems we address with this paper are not only of interest for this particular application domain but generally for all interactive graphical installations, which must be adapted to the existing architectural situation.
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| 33. |
- Seipel, Stefan, et al.
(författare)
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Oral Implant Treatment Planning in a Virtual Reality Environment
- 1998
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Ingår i: Computer Methods and Programs in Biomedicine. - 0169-2607 .- 1872-7565. ; 57:1-2, s. 95-103
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Tidskriftsartikel (refereegranskat)abstract
- A system for three-dimensional oral implant treatment planning is presented. Virtual reality technologies are used in order to improve the human image interpretation and planning performance. The methods described are based on computer tomography (CT) data of the mandible and of the maxilla. A novel approach to volume rendering and voxel based modelling of implants is introduced which allows interactive three-dimensional manipulation of the anatomic model and real-time manipulation of virtual implants. A spline-based reconstruction method is described to assess the implant site in a clinically oriented view with regard to bone structures and angulation. Two parameters are deduced which represent the bone properties at the surface of implants. While an implant is navigated with six degrees of freedom, these parameters are acoustically rendered which is a novel approach to exploration of spatial bone properties in a CT data set.
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| 36. |
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