A study on using colors to represent the floating population of tourists and local residents on the map by each hour in each month. The resulting visualization can assist the decision-making in various areas by providing a vivid description of the movement of people in a day.

L’holographie est souvent considérée comme la technologie de visualisation 3D la plus prometteuse, puisqu'elle fournit l'illusion du relief la plus naturelle et la plus réaliste possible. Toutefois, pour trouver application dans le domaine de la visioconférence ou de la téléprésence, les méthodes de génération numérique d'hologrammes doivent produire des scènes réalistes avec une forte illusion de profondeur, et ce en temps réel. Cette thèse se situe dans ce contexte et est organisé en deux parties. Dans la première partie de ce travail, nous avons proposé deux algorithmes de synthèse d'hologrammes permettant de se rapprocher du temps réel. Tout d'abord, nous avons développé une méthode combinant deux approches complémentaires: les approches point-source et wave-field. Alors que les méthodes de l'état de l'art réduisent la complexité de calcul de ces deux approches indépendamment, notre méthode tire parti de chacune d'entre elles. De cette manière, le temps de calcul de l'hologramme a été réduit de plus de 65% par rapport aux méthodes point-source et wave-field conventionnelles. Deuxièmement, nous avons cherché à accélérer cette méthode hybride en supprimant les redondances temporelles entre les trames consécutives d'une vidéo 3D. Pour chaque image, l'algorithme détecte les changements dans la scène et met à jour l'hologramme des points affectés. Étant donné que seules de petites régions de l'hologramme sont mises à jour, la charge de calcul est considérablement réduite, permettant le calcul d’hologrammes couleur à 60 images par seconde. Dans la deuxième partie de ce travail, nous avons proposé deux algorithmes afin d'améliorer la qualité visuelle des scènes. Tout d'abord, nous avons perfectionné la méthode hybride pour tenir compte des occultations dans la scène. Pour cela, nous avons conçu une méthode efficace pour le calcul de l'occultation d'une onde lumineuse par un point. Cette méthode reproduit les occultations sans augmenter de manière significative le temps de calcul de la méthode hybride originale. Enfin, nous avons proposé une méthode pour le calcul d'un hologramme à partir de données multivue-plus-profondeur (MVD) avec prise en compte des réflexions spéculaires. Selon cette méthode, la géométrie de la scène est reconstruite à partir des données MVD sous la forme d'un nuage de points, ce qui permet de n'utiliser que quelques projections de la scène. En outre, afin de tenir compte de réflexions spéculaires, chaque point de la scène est considéré avoir une émission différente selon les directions. Enfin, la lumière émise par la scène est propagée dans le plan de l'hologramme. Les résultats expérimentaux montrent que cette méthode reproduit tous les indices de la profondeur et l'illumination précise de la scène avec une complexité de calcul réduite. / Holography is often considered as the most promising 3D visualization technology, since it can produce the most realistic and natural depth illusion to the naked eye. However, in order to have application in the field of videoconferencing or telepresence systems, hologram synthesis methods should be able to produce realistic 3D scenes with strong depth illusion in real-time. This thesis falls within this context and is organized into two parts. In the first part of this work, we investigated two novel algorithms in order to get closer to real-time computation. First, we designed a fast hologram calculation method by combining two approaches which complement one another: the point-source and wave-field approaches. Whereas previously proposed methods reduced the computational complexity of these approaches independently, our method takes advantages from both of them. By this way, the hologram calculation time has been reduced by more than 65% compare to the conventional point-source and wave-field methods. Second, we further accelerated this hybrid method by removing temporal redundancies between consecutive frames of a 3D video. For each video frame, the algorithm detects changes in the scene and updates the hologram of only affected scene points. Since only small regions of the hologram are updated at each video frame, this method allows the computational burden to be dramatically reduced, enabling the computation of colorful video holograms at 60 frames per second. In the second part of this work, we proposed two algorithms in order to enhance the visual quality of displayed scenes. First, we improved the hybrid method to take into account occlusions between objects in the scene. To this end, we designed an efficient algorithm for light shielding between points and light waves. Experimental results revealed that this method provides occlusion effect without significantly increasing the hologram calculation time of the original hybrid method. Finally, we proposed a hologram computation method from Multiview-plus-depth (MVD) data with rendering of specular reflections. In this method, the 3D scene geometry is first reconstructed from the MVD data as a layered point-cloud, enabling the use of only a few perspective projections of the scene. Furthermore, in order to take into account specular reflections, each scene point is considered to emit light differently in all the directions. Finally, light scattered by the scene is numerically propagated towards the hologram plane in order to get the final hologram. Experimental results show that the proposed method is able to provide all the human depth cues and accurate shading of the scene with reduced computational complexity.

<p>The main goal of this thesis is to show the strength of combining datasets from two different types of sensors to find anomalies in their data. The sensors used in this thesis are a hyperspectral camera and a scanning 3-D laser.</p><p>The report can be divided into two main parts. The first part discusses the properties of one of the datasets and how these are used to isolate anomalies. An issue to deal with here is not only what properties to look at, but how to make the process automatic. The information retained from the first dataset is then used to make intelligent choices in the second dataset. Again, one of the challenges is to make this process automatic and accurate. The second part of the project consists of presenting the results in a way that gives the most information to the user. This is done with a graphical user interface that allows the user to manipulate the way the result is presented.</p><p>The conclusion of this project is that the information from the combined sensor datasets gives better results than the sum of the information from the individual datasets. The key of success is to play to the strengths of the datasets in question. An important block of the work in this thesis, the calibration of the two sensors, was completed by Kevin Chan as his thesis work in Electrical Engineering at the University of Lund. His contribution gave access to calibrated data that supported the results presented in this report.</p>

The main goal of this thesis is to show the strength of combining datasets from two different types of sensors to find anomalies in their data. The sensors used in this thesis are a hyperspectral camera and a scanning 3-D laser. The report can be divided into two main parts. The first part discusses the properties of one of the datasets and how these are used to isolate anomalies. An issue to deal with here is not only what properties to look at, but how to make the process automatic. The information retained from the first dataset is then used to make intelligent choices in the second dataset. Again, one of the challenges is to make this process automatic and accurate. The second part of the project consists of presenting the results in a way that gives the most information to the user. This is done with a graphical user interface that allows the user to manipulate the way the result is presented. The conclusion of this project is that the information from the combined sensor datasets gives better results than the sum of the information from the individual datasets. The key of success is to play to the strengths of the datasets in question. An important block of the work in this thesis, the calibration of the two sensors, was completed by Kevin Chan as his thesis work in Electrical Engineering at the University of Lund. His contribution gave access to calibrated data that supported the results presented in this report.

Les points critiques d’une fonction scalaire (minima, points col et maxima) sont des caractéristiques importantes permettant de décrire de gros ensembles de données, comme par exemple les données topographiques. L’acquisition de ces données introduit souvent du bruit sur les valeurs. Un grand nombre de points critiques sont créés par le bruit, il est donc important de supprimer ces points critiques pour faire une bonne analyse de ces données. Le complexe de Morse-Smale est un objet mathématique qui est étudié dans le domaine de la Visualisation Scientifique car il permet de simplifier des fonctions scalaires tout en gardant les points critiques les plus importants de la fonction étudiée, ainsi que les liens entre ces points critiques. Nous proposons dans cette thèse une méthode permettant de construire une fonction qui correspond à un complexe de Morse-Smale d’une fonction définie sur R^2 après suppression de paires de points critiques dans celui-ci.Tout d’abord, nous proposons une méthode qui définit une surface interpolant des valeurs de fonction aux points d’une grille de façon monotone, c’est-à-dire en ne créant pas de point critique. Cette surface est composée d’un ensemble de patchs de Bézier triangulaires cubiques assemblés de telle sorte que la surface soit globalement C^1. Nous donnons des conditionssuffisantes sur les valeurs d fonction et les valeurs de dérivées partielles aux points de la grille afin que la surface soit croissante dans la direction (x+y). Il n’est pas évident de créer des valeurs de dérivées partielles en chaque point de la grille vérifiant ces conditions. C’est pourquoi nous introduisons deux algorithmes : le premier permet de modifier des valeurs de dérivées partielles données en entrée afin que celles-ci vérifient les conditions et le second calcule des valeurs de dérivées partielles à partir des valeurs de fonctions aux points de la grille.Ensuite, nous décrivons une méthode de reconstruction de champs scalaires à partir de complexes de Morse-Smale simplifiés. Pour cela, nous commençons par approximer les 1-cellules (les liens entre les points critiques dans le complexe de Morse-Smale, ceux-ci sont décrits par des polylignes) par des courbes composées de courbes de Bézier cubiques. Nous décrivons ensuite comment notre interpolation monotone de valeurs aux points d’une grille est utilisée pour construire des surfaces monotones interpolant les courbes construites précédemment. De plus, nous montrons que la fonction reconstruite contient tout les points critiques du complexe de Morse-Smale simplifié et n’en contient aucun autre. / Critical points of a scalar function (minima, saddle points and maxima) are important features to characterize large scalar datasets, like topographic data. But the acquisition of such datasets introduces noise in the values. Many critical points are caused by the noise, so there is a need to delete these extra critical points. The Morse-Smale complex is a mathematical object which is studied in the domain of Visualization because it allows to simplify scalar functions while keeping the most important critical points of the studied function and the links between them. We propose in this dissertation a method to construct a function which corresponds to a Morse-Smale complex defined on R^2 after the suppression of pairs of critical points.Firstly, we propose a method which defines a monotone surface (a surface without critical points).This surface interpolates function values at a grid points. Furthermore, it is composed of a set of triangular cubic Bézier patches which define a C^1 continuous surface. We give sufficient conditions on the function values at the grid points and on the partial derivatives at the grid points so that the surface is increasing in the (x+y) direction. It is not easy to compute partial derivatives values which respect these conditions. That’s why we introduce two algorithms : the first modifies the partial derivatives values on input such that they respect the conditions and the second computes these values from the function values at the grid points.Then, we describe a reconstruction method of scalar field from simplified Morse-Smale complexes. We begin by approximating the 1-cells of the complex (which are the links between the critical points, described by polylines) by curves composed of cubic Bézier curves. We then describe how our monotone interpolant of values at grid points is used to construct monotone surfaces which interpolate the curves we computed before. Furthermore, we show that the function we compute contains all the critical points of the simplified Morse-Smale complex and has no others.

The purpose of the study was to investigate Virtual Reality as a visualization tool for communicating light and lighting design in projects. In the study, we sought to answer whether there are differences in light and spatial experience between a VR model and a physical environment. The VR model was created on the basis of visual evaluations of a physical environment and was therefore not based on light technical parameters (illuminance, luminance etc.). The data was collected by conducting an experiment where 35 subjects were put in two groups, an experiment group (n=30) and a control group (n=5). The subjects gave numerical input through a leader-led questionnaire about their experience of light and spatial dimensions in the VR model and the physical environment. The results showed that there was no significant statistical difference between how the experiment group experienced the light in the VR model compared to the physical environment. The experiment group also considered that the spatial dimensions in the two environments were equal except for a minor deviation concerning how high/low they experienced the room. In the results, a difference can be seen in how test subject with and without knowledge of light evaluated the environments which suggests that there may be a deficiency in how design is communicated between people with knowledge of light and people without knowledge of light. Following these findings, the presenting method of visualizing light in VR seems very promising and should be seen as a basis for further practical use of the tool.

Eye tracking-teknologi har blivit mer och mer populärt att använda inom user experience-forskning med åren. I den här studien undersöks hur forskare väljer att visualisera eye tracking-data, vad dessa visualiseringar fyller för syfte och hur de skapades. Målet med studien är att identifiera hur forskare inom området motiverar deras val av visualiseringsmetod och om de redogör för hur de genererat deras figurer för visualisering. Studien är en litteraturstudie där artiklar har analyserats för att hitta jämförbar data. Alla artiklar är relaterade till user experience och har utfört sina studier med hjälp av eye tracking-teknologi. Deras eye tracking data samlas från webbaserade plattformar och visualiserasgenom figurer inkluderade i texterna. Resultat visar att samtliga studier inte motiverar deras val av visualiseringsmetod eller redogör på ett tydligt sätt hur de skapat visualiseringar. Samtliga studier gör också antaganden och slutsatser om användarupplevelsen av deras gränssnitt baserat på deras respektive visualiseringar trots att skapandet av visualiseringar inte redogjorts. / Eye tracking-technology has become increasingly popular to use in user experience research over the years. This study examines how researchers choose to visualize eye tracking-data, the purposes these visualizations serve, and how they were created. The aim of the study is to identify how researchers in the field justify their choice of visualization method and whether they explain how they generated their figures for visualization. The study is a literature review where articles have been analyzed to find comparable data. All articles are related to user experience and have conducted their studies utilizing eye tracking-technology. Their eye tracking data is collected from web-based platforms and visualized through figures included in the texts. The results show that none of the studies justify their choice of visualization method or clearly explain how they created their visualizations. All studies also make assumptions and draw conclusions about the user experience of their interfaces based on their respective visualizations, despite not providing details about the creation of said visualizations.