| 1. |
- Jönsson, Daniel
(författare)
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Enhancing Salient Features in Volumetric Data Using Illumination and Transfer Functions
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The visualization of volume data is a fundamental component in the medical domain. Volume data is used in the clinical work-flow to diagnose patients and is therefore of uttermost importance. The amount of data is rapidly increasing as sensors, such as computed tomography scanners, become capable of measuring more details and gathering more data over time. Unfortunately, the increasing amount of data makes it computationally challenging to interactively apply high quality methods to increase shape and depth perception. Furthermore, methods for exploring volume data has mostly been designed for experts, which prohibits novice users from exploring volume data. This thesis aims to address these challenges by introducing efficient methods for enhancing salient features through high quality illumination as well as methods for intuitive volume data exploration.Humans are interpreting the world around them by observing how light interacts with objects. Shadows enable us to better determine distances while shifts in color enable us to better distinguish objects and identify their shape. These concepts are also applicable to computer generated content. The perception in volume data visualization can therefore be improved by simulating real-world light interaction. This thesis presents efficient methods that are capable of interactively simulating realistic light propagation in volume data. In particular, this work shows how a multi-resolution grid can be used to encode the attenuation of light from all directions using spherical harmonics and thereby enable advanced interactive dynamic light configurations. Two methods are also presented that allow photon mapping calculations to be focused on visually changing areas.The results demonstrate that photon mapping can be used in interactive volume visualization for both static and time-varying volume data.Efficient and intuitive exploration of volume data requires methods that are easy to use and reflect the objects that were measured. A value that has been collected by a sensor commonly represents the material existing within a small neighborhood around a location. Recreating the original materials is difficult since the value represents a mixture of them. This is referred to as the partial-volume problem. A method is presented that derives knowledge from the user in order to reconstruct the original materials in a way which is more in line with what the user would expect. Sharp boundaries are visualized where the certainty is high while uncertain areas are visualized with fuzzy boundaries. The volume exploration process of mapping data values to optical properties through the transfer function has traditionally been complex and performed by expert users. A study at a science center showed that visitors favor the presented dynamic gallery method compared to the most commonly used transfer function editor.
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| 2. |
- Lundin Palmerius, Karljohan, 1977-, et al.
(författare)
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Visualizing and Exploring Heat in a Science Center
- 2022
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Ingår i: Thermal Cameras in Science Education. - Cham, Schweiz : Springer. - 9783030852870 - 9783030852900 - 9783030852887 ; , s. 187-203
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Recent research shows that infrared cameras can help students visualize and interpret notoriously challenging thermal concepts. This chapter describes the application of thermal visualization in a public setting. Specifically, we present the design and implementation of an augmented reality system for the real-time projection of thermal imagery onto objects. Examples of hands-on activities for visualizing thermal processes with the system include conduction and insulation, rubber band thermodynamics, friction, impact heating, enthalpy of chemical reactions, radiation wavelength, mixing liquids, and heat of evaporation. We discuss how the interactive activities might provide pedagogical opportunities for accessing and engaging with thermal phenomena in a science center context. Practical considerations of the system for public exhibition spaces are also given attention.
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| 3. |
- Granlund, Gösta H.
(författare)
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A Nonlinear, Image-content Dependent Measure of Image Quality
- 1977
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In recent years, considerable research effort has been devoted to the development of useful descriptors for image quality. The attempts have been hampered by i n complete understanding of the operation of the human visual system. This has made it difficult to relate physical measures and perceptual traits.A new model for determination of image quality is proposed. Its main feature is that it tries to invoke image content into consideration. The model builds upon a theory of image linearization, which means that the information in an image can well enough be represented using linear segments or structures within local spatial regions and frequency ranges. This implies a l so a suggestion that information in an image has to do with one- dimensional correlations. This gives a possibility to separate image content from noise in images, and measure them both.Also a hypothesis is proposed that the visual system of humans does in fact perform such a linearization.
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| 4. |
- Heintz, Fredrik, 1975-, et al.
(författare)
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Introducing Programming and Digital Competence in Swedish K-9 Education
- 2017
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Ingår i: Informatics in Schools. - Cham : Springer. - 0302-9743 .- 1611-3349. - 9783319714820 - 9783319714837 ; , s. 117-128
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Konferensbidrag (refereegranskat)abstract
- The role of computer science and IT in Swedish schools has varied throughout the years. In fall 2014, the Swedish government gave the National Agency for Education (Skolverket) the task of preparing a proposal for K–9 education on how to better address the competences required in a digitalized society. In June 2016, Skolverket handed over a proposal introducing digital competence and programming as interdisciplinary traits, also providing explicit formulations in subjects such as mathematics (programming, algorithms and problem-solving), technology (controlling physical artifacts) and social sciences (fostering aware and critical citizens in a digital society). In March 2017, the government approved the new curriculum, which needs to be implemented by fall 2018 at the latest. We present the new K–9 curriculum and put it in a historical context. We also describe and analyze the process of developing the revised curriculum, and discuss some initiatives for how to implement the changes.
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| 5. |
- Samini, Ali, et al.
(författare)
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A User Study on Touch Interaction for User-Perspective Rendering in Hand-Held Video See-Through Augmented Reality
- 2016
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Ingår i: Augmented Reality, Virtual Reality, and Computer Graphics. - Cham : Springer. - 9783319406510 - 9783319406503 ; , s. 304-317
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Konferensbidrag (refereegranskat)abstract
- This paper presents a user study on touch interaction with hand-held Video See-through Augmented Reality (V-AR). In particular, the commonly used Device Perspective Rendering (DPR) is compared with User Perspective Rendering (UPR) with respect to both performance and user experience and preferences. We present two user study tests designed to mimic the tasks that are used in various AR applications.Looking for an object and selecting when it’s found, is one of the most used tasks in AR software. Our first test focuses on comparing UPR and DPR in a simple find and selection task. Manipulating the pose of a virtual object is another commonly used task in AR. The second test focuses on multi-touch interaction for 6 DoF object pose manipulation through UPR and DPR.
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| 6. |
- Samini, Ali, 1979-
(författare)
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Perspective Correct Hand-held Augmented Reality for Improved Graphics and Interaction
- 2018
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- With Augmented Reality, also termed AR, a view of the real world is augmented by superimposing computer-generated graphics, thereby enriching or enhancing the perception of the reality. Today, lots of applications benefit from AR in different areas, such as education, medicine, navigation, construction, gaming, and multiple other areas, using primarily head-mounted AR displays and AR on hand-held smart devices. Tablets and phones are highly suitable for AR, as they are equipped with high resolution screens, good cameras and powerful processing units, while being readily available to both industry and home use. They are used with video see-through AR, were the live view of the world is captured by a camera in real time and subsequently presented together with the computer graphics on the display.In this thesis I put forth our recent work on improving video see-through Augmented Reality graphics and interaction for hand-held devices by applying and utilizing user perspective. On the rendering side, we introduce a geometry-based user perspective rending method aiming to align the on screen content with the real view of the world visible around the screen. Furthermore, we introduce a device calibration system to compensate for misalignment between system parts. On the interaction side we introduce two wand-like direct 3D pose manipulation techniques based on this user perspective. We also modified a selection technique and introduced a new one suitable to be used with our introduced manipulation techniques. Finally, I present several formal user studies, evaluating the introduced techniques and comparing them with concurrent state-of-the-art alternatives.
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| 7. |
- Stenlund, Jörgen, 1959-
(författare)
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Travelling through time : Students’ interpretation of evolutionary time in dynamic visualizations
- 2019
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Evolutionary knowledge is important to understand and address contemporary challenges such as loss of biodiversity, climate change and antibiotic resistance. An important aspect that is considered to be a threshold concept in teaching and learning about evolution is the time it involves. The history of evolution comprises several scales of magnitude, some of which are far from direct human experience and therefore difficult to understand. One way of addressing this issue is to use dynamic visualizations that represent time, for example, to facilitate teaching and learning about evolution.This thesis investigates how students’ comprehension of evolution and evolutionary time can be facilitated by visualizations in educational settings. Two different dynamic visualizations were investigated. In paper I different temporal versions of a spatio-temporal animation depicting hominin evolution were explored. The temporal information was expressed as one or several timelines along which an animated cursor moved, indicating the rate of time. Two variables, the number of timelines with different scales, and the mode of the default animated time rate (either constant throughout the animation or decreasing as the animation progressed), were combined to give four different time representations. The temporal aspects investigated were undergraduate students' ability to find events at specific times, comprehend order, comprehend concurrent events, comprehend the length of time intervals, and their ability to compare the lengths of time intervals.In paper II, perceptions and comprehension of temporal aspects in an interactive, multi-touch tabletop application, DeepTree, were investigated. This application depicts the tree of life. The focus was on the interactive aspects, especially how the zooming feature was perceived, but also on any misinterpretations associated with the interaction. The same temporal aspects listed for paper I were also implicitly investigated.The findings indicate that handling the problem of large differences in scale by altering the rate of time in the visualization can facilitate perception of certain temporal aspects while, at the same time, can hinder a correct comprehension of other temporal aspects. Findings concerning DeepTree indicate that the level of interactions varies among users, and that the zooming feature is perceived in two ways, either as a movement in time or as a movement in the metaphorical tree. Several misinterpretations were observed, for example the assumption that the zooming time in the tree corresponds to real time, that there is an implicit coherent timeline along the y-axis of the tree, and that more nodes along a branch corresponds to a longer time.The research reported in this thesis supports the claim that careful choice, and informed use of visualizations matters, and that different visualizations are best suited for different educational purposes
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| 8. |
- Gustavson, Stefan, 1965-
(författare)
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2D Shape Rendering by Distance Fields
- 2012
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Ingår i: OpenGL Insights. - : CRC Press. - 9781439893760 ; , s. 173-182
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- We present a method for real time rendering of anti-aliased curved contours, combining recent results from research on distance transforms and modern GPU shading using GLSL. The method is capable of rendering glyphs and symbols of very high quality at arbitrary levels of magnification and minification, and it is both versatile and easy to use.
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| 9. |
- Gustavson, Stefan, 1965-
(författare)
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Procedural Textures in GLSL
- 2012
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Ingår i: OpenGL Insights. - : CRC Press. - 9781439893760 ; , s. 105-119
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- Procedural shading has been a versatile and popular tool for off-line rendering for decades. With the ever increasing speed and computational capabilities of modern GPUs, it is now becoming possible to use procedural shading also for real time rendering. This chapter is an introduction to some classic procedural shading techniques, adapted for real time use.
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| 10. |
- Ho, Quan, 1975-, et al.
(författare)
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A Web-Enabled Visualization Toolkit for Geovisual Analytics
- 2012
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Ingår i: Information Visualization. - : Sage Publications. - 1473-8716 .- 1473-8724. ; 11:1, s. 22-42
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Tidskriftsartikel (refereegranskat)abstract
- A framework and class library (GAV Flash) implemented in Adobe’s ActionScript is introduced, designed with the intention to significantly shorten the time and effort needed to develop customized web-enabled applications for geovisual analytics tasks. Through an atomic layered component architecture, GAV Flash provides a collection of interactive geo- and information visualization representations for exploring high dimensional spaces and extended with motion behavior. Versatile interaction methods are drawn from many data visualization research areas and optimized for dynamic web visualization of spatio-temporal and multivariate data. Based on layered component thinking and the use of programming interface mechanism the GAV Flash architecture is open and facilitates the creation of new or improved versions of existing components so that ideas can be tried out or optimized rapidly in a fully functional environment. Not only is GAV Flash a tool for interactive visualization but also supports storytelling around visual analytics in which visual representations not only serve as a discovery tool for individuals but also as a mean to share stories among users fostering a social style of collaborative data analysis. A mechanism “snapshot” for saving the explorative results of a reasoning process is introduced that aids collaboration and publication of gained insight and knowledge embedded as dynamic visualizations in blogs or web pages with associative metadata or “storytelling”.
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