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Simulation of fractures
(2014)
Real-time computing often avoids the simulation of fractures due to its complexity. The field of engineering science provides methods to create these simulations to improve games and other applications. Steadily rising computer capacities allow suitable simulations on a real-time basis and make this aspect increasingly interesting. The topic and aim of this research is to simulate fractures of stiff bodies. The primary objective is the physical plausibility and performance of the application. This thesis analyses the potential of computer science to realize the simulation of fractures.
Three existing as well as one self-created were implemented and analysed. The works "Real time simulation of deformation and Fracture of stiff material" from Müller et al., "real time simulation of Brittle Fracture using Modal analysis" from Glondu et al. and "Fast and Controllable simulation of the Shattering of Brittle Objects" from Smith et al. form the basis of this thesis. The introduced methods use different computation of forces and fractures. The developed procedure uses the idea of generating secondary breaks. The approaches were implemented based on the Bullet physics-engine. The results of the work show that physically based breaks are realizable on a real-time basis.
The analysis of the physical methods demonstrates that their performance mainly depends on the constitution of the used objects. This thesis shows that the further investigation of this topic can discover new possibilities. The improvement of the realism in virtual worlds can be achieved by executing physically plausible methods.
In scientific data visualization huge amounts of data are generated, which implies the task of analyzing these in an efficient way. This includes the reliable detection of important parts and a low expenditure of time and effort. This is especially important for the big-sized seismic volume datasets, that are required for the exploration of oil and gas deposits. Since the generated data is complex and a manual analysis is very time-intensive, a semi-automatic approach could on one hand reduce the time required for the analysis and on the other hand offer more flexibility, than a fully automatic approach.
This master's thesis introduces an algorithm, which is capable of locating regions of interest in seismic volume data automatically by detecting anomalies in local histograms. Furthermore the results are visualized and a variety of tools for the exploration and interpretation of the detected regions are developed. The approach is evaluated by experiments with synthetic data and in interviews with domain experts on the basis of real-world data. Conclusively further improvements to integrate the algorithm into the seismic interpretation workflow are suggested.
In dieser Arbeit wird eine Unterrichtsreihe beschrieben, welche aus den drei Bereichen „mathematische Relationen“, „Datenbanken in Sozialen Netzwerken“ und „Datenschutz“ zusammengesetzt ist. Zu jedem Bereich wird ein eigener Unterrichtsentwurf präsentiert.
Außerdem wurde im Rahmen der vorliegenden Arbeit ein Programm zur Visualisierung der Relationen des Sozialen Netzwerks Instahub entworfen, welches im Anschluss an die Beschreibung der Unterrichtsreihe aufgeführt wird.
In order to plan the interior of a room, various programs for computers,
smart phones or head-mounted displays are available. The transfer to the
real environment is a difficult task. Therefore an augmented reality approach
is developed to illustrate the planning in the real room. If several
people want to contribute their ideas, conventional systems require to
work on one device together. The aim of this master thesis is to design and
develop a collaborative spatial planning application in augmented reality.
The application is developed in Unity with ARCore and C#.
Soziale Netzwerke spielen im Alltagsleben der Schülerinnen und Schüler eine entscheidende Rolle. Im Rahmen der vorliegenden Masterarbeit wurde ein Konzept für die Anzeige von Profilvorschlägen innerhalb des sozialen Netzwerks „InstaHub“, welches ein speziell für den Informatikunterricht programmiertes Werkzeug zum Thema „Datenbanken“ darstellt, entwickelt. Als Hürde stellte sich dabei dar, dass von den etablierten sozialen Netzwerken nur wenig bis gar keine Informationen über die Berechnung von Profil- oder Freundschaftsvorschlägen preisgegeben werden. Daher wurde zunächst das Wesen von Beziehungen zwischen Menschen in nicht-internetbasierten und in internetbasierten sozialen Netzwerken sowie die Gründe für Beziehungen zwischen Menschen in diesen Netzwerken dargelegt. Anhand der Beobachtung von Vorschlägen in anderen sozialen Netzwerken sowie der in InstaHub gespeicherten Nutzerdaten wurde ein Algorithmus für Profilvorschläge in InstaHub entworfen und mitsamt einer passenden Visualisierung entsprechend implementiert. Den zweiten Teil der Arbeit bildete eine Unterrichtseinheit für die Sekundarstufe II mit dem Thema Gefahren der Erzeugung und Verarbeitung von personenbezogenen Daten. In der Unterrichtseinheit dienen die Profilvorschläge in InstaHub, die auf von InstaHub über dessen Nutzer gesammelten Daten aufbauen, als Einstieg in die Thematik. Anschließend wird der Fokus von sozialen Netzwerken auf andere Online-Dienste erweitert und auf die Verarbeitung und Weitergabe dieser Daten eingegangen.
With the emergence of current generation head-mounted displays (HMDs), virtual reality (VR) is regaining much interest in the field of medical imaging and diagnosis. Room-scale exploration of CT or MRI data in virtual reality feels like an intuitive application. However in VR retaining a high frame rate is more critical than for conventional user interaction seated in front of a screen. There is strong scientific evidence suggesting that low frame rates and high latency have a strong influence on the appearance of cybersickness. This thesis explores two practical approaches to overcome the high computational cost of volume rendering for virtual reality. One lies within the exploitation of coherency properties of the especially costly stereoscopic rendering setup. The main contribution is the development and evaluation of a novel acceleration technique for stereoscopic GPU ray casting. Additionally, an asynchronous rendering approach is pursued to minimize the amount of latency in the system. A selection of image warping techniques has been implemented and evaluated methodically, assessing the applicability for VR volume rendering.
Das Ziel der vorliegenden Masterarbeit ist es, einen Einführungskurs in die Computervisualistik mit dem Schwerpunkt Computergrafik zu konzeptionieren und zu prototypisieren. Der Kurs sollte Grundlagen der Computergrafik vermitteln und dabei Bezüge zu anderen Veranstaltungen des Studiums herstellen, um Motivation und Verständnis für die komplexen Zusammenhänge der Studieninhalte in der Computervisualistik zu schaffen. Der aktuelle Studiengangplan weist hier bislang ein erkennbares Defizit auf. Für den Einführungskurs wurden prototypische Lerneinheiten auf Grundlage der didaktischen Methode der Moderation und unter Verwendung von Unity entwickelt. Konzept und Prototypen wurden an Probanden ohne informationstechnischen Hintergrund evaluiert. Die Ergebnisse zeigten, dass Unity eine geeignete Oberfläche für die Vermittlung der Informationen bietet. Diese stieß auf Akzeptanz und konnte leichte Zugänglichkeit bei den Probanden aufweisen, obwohl die Lerneinheiten selbst kleinere Schwächen aufwiesen. Im Anschluss an die erste Evaluationsphase wurde eine qualitative Umfrage mit Alumini der Computervisualistik durchgeführt. Die Ergebnisse bestätigten den Bedarf nach einer einführenden Veranstaltung zur Orientierung und zur Förderung von Motivation und Verständnis für die breiten Themengebiete der Computervisualistik.
In this thesis, we deal with the question if challenge, flow and fun in computer games are related to each other, and which influence the motivational, psychological components motivation of success, motivation of failure and the chance of success do have. In addition, we want to know if a free choice in the level of difficulty is the optimal way to flow. To examine these theories, a study based on an online survey was executed, in which the participants played the game “flOw“. The results were evaluated with the help of a two-factorial analysis of variance with repeated measurement and tests on correlation. Thereby we found out that there actually exists a relation between challenge, flow and fun and that motivation does matter indirectly.
This thesis presents a prototypical application for speech therapy as a therapeutical tool, simulating the articulation of German phonemes and the swallowing reflex. A special attention is given to a three-dimensional visualization of anatomical models of the pharyngolaryngeal region, which can be used in an interactive way. For examining the benefits of such an application in relation to conventional therapy mediums, the thesis considers iteratively the requirements of speech therapists.
One of the greatest goals in computer graphics is the aesthetic representation of objects. In addition to conventional methods, another field focuses on non-photorealistic renderings. The so-called example-based rendering is an area where users can transfer their art style to a pre-computed 3D rendering, using a hand-painted template. There are some algorithms that already provide impressive results, but their problem is that most of these procedures count as offline methods and are not able to produce results in real-time. For this reason, this work show a method that satisfies this condition. In addition, the influence of the run-time reduction on the results is investigated. Requirements are defined, to which the method and its results are examined. Other methods in this field are referenced and compared with their results.
Statistical Shape Models (SSMs) are one of the most successful tools in 3Dimage analysis and especially medical image segmentation. By modeling the variability of a population of training shapes, the statistical information inherent in such data are used for automatic interpretation of new images. However, building a high-quality SSM requires manually generated ground truth data from clinical experts. Unfortunately, the acquisition of such data is a time-consuming, error-prone and subjective process. Due to this effort, the majority of SSMs is often based on a limited set of this ground truth training data, which makes the models less statistically meaningful. On the other hand, image data itself is abundant in clinics from daily routine. In this work, methods for automatically constructing a reliable SSM without the need of manual image interpretation from experts are proposed. Thus, the training data is assumed to be the result of any segmentation algorithm or may originate from other sources, e.g. non-expert manual delineations. Depending on the algorithm, the output segmentations will contain errors to a higher or lower degree. In order to account for these errors, areas of low probability of being a boundary should be excluded from the training of the SSM. Therefore, the probabilities are estimated with the help of image-based approaches. By including many shape variations, the corrupted parts can be statistically reconstructed. Two approaches for reconstruction are proposed - an Imputation method and Weighted Robust Principal Component Analysis (WRPCA). This allows the inclusion of many data sets from clinical routine, covering a lot more variations of shape examples. To assess the quality of the models, which are robust against erroneous training shapes, an evaluation compares the generalization and specificity ability to a model build from ground truth data. The results show, that especially WRPCA is a powerful tool to handle corrupted parts and yields to reasonable models, which have a higher quality than the initial segmentations.
This work covers techniques for interactive and physically - based rendering of hair for computer generated imagery (CGI). To this end techniques
for the simulation and approximation of the interaction of light with hair are derived and presented. Furthermore it is described how hair, despite such computationally expensive algorithms, can be rendered interactively.
Techniques for computing the shadowing in hair as well as approaches to render hair as transparent geometry are also presented. A main focus of
this work is the DBK-Buffer, which was conceived, implemented and evaluated. Using the DBK-Buffer, it is possible to render thousands of hairs as
transparent geometry without being dependent on either the newest GPU hardware generation or a great amount of video memory. Moreover, a comprehensive evaluation of all the techniques described was conducted with respect to the visual quality, performance and memory requirements. This
revealed that hair can be rendered physically - based at interactive or even at real - time frame rates.
In current research of the autonomous mobile robots, path planning is still a very important issue.
This master's thesis deals with various path planning algorithms for the navigation of such mobile systems. This is not only to determine a collision-free trajectory from one point to another. The path should still be optimal and comply with all vehicle-given constraints. Especially the autonomous driving in an unknown and dynamic environment poses a major challenge, because a closed-loop control is necessary and thus a certain dynamic of the planner is demanded.
In this paper, two types of algorithms are presented. First, the path planner, based on A*, which is a common graph search algorithm: A*, Anytime Repairing A*, Lifelong Planning A*, D* Lite, Field D*, hybrid A*. Second, the algorithms which are based on the probabilistic planning algorithm Rapidly-exploring Random Tree (Rapidly-exploring Random Tree, RRT*, Lifelong Planning RRT*), as well as some extensions and heuristics. In addition, methods for collision avoidance and path smoothing are presented. Finally, these different algorithms are evaluated and compared with each other.
Today, augmented reality is becoming more and more important in several areas like industrial sectors, medicine, or tourism. This gain of importance can easily be explained by its powerful extension of real world content. Therefore, augmented realty became a way to explain and enhance the real world information. Yet, to create a system which can enhance a scene with additional information, the relation between the system and the real world must be known. In order to establish this relationship a commonly used method is optical tracking. The system calculates its relation to the real world from camera images. To do so, a reference which is known is needed in the scene to serve as an orientation. Today, this is mostly a 2D-marker or a 2D-texture. These are placed in the real world scenery to serve as a reference. But, this is an intrusion in the scene. That is why it is desirable that the system works without such an additional aid. An strategy without manipulating the scene is object-tracking. In this approach, any object from the scene can be used as a reference for the system. As an object is far more complex than a marker, it is harder for the system to establish its relationship with the real world. That is why most methods for 3D-object-tracking reduce the object by not using the whole object as reference. The focus of this thesis is to research how a whole object can be used as a reference in a way that either the system or the camera can be moved in any 360 degree angle around the object without loosing the relation to the real world. As a basis the augmented reality framework, the so called VisionLib, is used. Extensions to this system for 360 degree tracking are implemented in different ways and analyzed in the scope of this work. Also, the different extensions are compared. The best results were achieved by improving the reinitialization process. With this extension, current camera images of the scene are given to the system. With the hek of these images, the system can calculate the relation to the real world faster in case the relation went missing.
Die vorliegende Masterarbeit thematisiert die Evaluation einer sprachgesteuerten Lösung in der Produktion mit multimodaler Eingabe. Dabei wurden die Usability und die Benut-zerfreundlichkeit eines gewählten Sprachdialogsystems bewertet. Die Bewertung wurde mit Hilfe von Benutzertests und eines modifizierten SASSI-Fragebogens durchgeführt. Weiterhin wurden auch technische Kriterien, wie die Wortfehlerrate und die Out-of-grammar Rate zur Hilfe gezogen. Für den Versuch wurden zwei verschiedene Szenarien aus einer realen Produktionsum-gebung definiert. Dabei sollten die Teilnehmer verschiedene Aufgaben mit Hilfe des Testsystems erledigen. Die Interaktion mit dem Sprachdialogsystem fand anhand von ge-sprochenen Befehlen statt, welche durch eine Grammatik definiert wurden. Die Sprach-kommandos wurden durch die Zuhilfenahme eines WLAN-Headsets an das Sprachsys-tem übertragen. Während des Versuchs wurden Aussagen der Teilnehmer protokolliert und die technischen Kriterien notiert.
Das Ergebnis der Evaluation verdeutlicht, dass das Sprachdialogsystem eine hohe Quali-tät bezüglich Usability und Benutzerfreundlichkeit aufweist. Dabei sind die Wortfehler-rate und die Out-of-grammar Rate sehr niedrig ausgefallen und das System wurde von den Benutzern deutlich positiv bewertet. Nichtsdestotrotz wurden einige Kritikpunkte ge-nannt, die zu einer Verbesserung des Systems beitragen können.
Zusätzlich zum Rendern wird die Rechenleistung moderner Grafikkarten immer häufiger auch für allgemeine Berechnungen (GPGPU) genutzt. Für die Umsetzung stehen verschiedene Möglichkeiten zur Verfügung, die von der Verwendung der Renderingpipeline bis zu eigenständigen Schnittstellen reichen. In dieser Arbeit werden mit Render-To-Texture, Transform Feedback, Compute Shader und OpenCL vier verschiedene GPGPU-Methoden untersucht. Anhand von Partikelsystemen werden sie hinsichtlich der benötigten Berechnungszeit, der GPU-Auslastung, Lines of Code und Portierbarkeit miteinander verglichen. Dazu wurden sowohl das N-Körper Problem, Smoothed Particle Hydrodynamics und ein Partikelschwarm als Partikelsysteme umgesetzt. Es konnte gezeigt werden, dass insbesondere OpenCL und Compute Shader sehr gute Ergebnisse liefern.
One of the fundamental decisions during the development of any system is the representation of data. In computer graphics, objects are usually represented as sets of triangles. There are however many different variants with their own strengths and weaknesses. This thesis will explore distancefields as a representation for objects. Distancefields are functions, which map every point in space to the distance to the closest surface point. While this description is very simple, a number of interesting properties can be derived, allowing for a multitude of shapes, operations and effects. An overview of the necessary background and methods is given. Furthermore, some extended or new approaches are presented, such as displaying implicit surfaces, approximating indirect illumination or implementing a GPU tracer.
Im Bereich Augmented Reality ist es von großer Bedeutung, dass virtuelle
Objekte möglichst realistisch in ein Kamerabild eingebettet werden. Nur
so ist es möglich, dem Nutzer eine immersive Erfahrung zu bieten. Dazu
gehört unter anderem, Verdeckung dieser Objekte korrekt zu behandeln.
Während schon verschiedene Ansätze existieren, dieses Verdeckungsproblem
zu beheben, wird in dieser Arbeit eine Lösung mittels Natural Image
Matting vorgestellt. Mit Hilfe einer Tiefenkamera wird das Kamerabild in
Vorder- und Hintergrund aufgeteilt und anschließend das virtuelle Objekt
im Bild platziert. Für Bereiche, in denen die Zugehörigkeit zu Vorder- oder
Hintergrund nicht eindeutig ist, wird anhand bekannter Pixel ein Transparenz-
Wert geschätzt. Es werden Methoden präsentiert, welche einen
Ablauf des Image Matting in Echtzeit ermöglichen. Zudem werden
Verbesserungsmöglichkeiten dieser Methoden präsentiert und gezeigt, dass
durch diese eine höhere Bildqualität für schwierige Szenen erreicht wird.
Einfluss eines Ausrichtungswerkzeugs auf die Bedienbarkeit in unbeaufsichtigten Eyetrackingsystemen
(2015)
Eye gaze trackers are devices that can estimate the direction of gaze of a person. Among usability testing eye tracking also allows persons with decreased limb mobility to control or to interact with the computer. The quality and availability of eye tracking equipment has been increasing while costs have been decreasing. This development leads to entering new markets by using eye tracking as an additional input dimension for a variety of applications. Up to now eye tracking has been supervised by qualified experts, who assured that the important conditions like position in front of the eye tracking device, calibration and light conditions has been kept, while using.
This thesis examines an adjustment tool, which is helping the user to adjust in front of the eye tracker and helping to keep this position during the experiment. Furthermore the accuracy while moving the head has been analysed. In this experiment an remote eye gaze tracker has been used to control a game character in the video game called 'Schau Genau!'. The goal was to determine whether the game is playable without the barrier of adjusting and calibration. The results show that adjusting in front of an eye tracker is not a problem, keeping this position is. Small changes of the head position after the calibration process leads to a lack of accuracy. Giving up the calibration and using someone else calibration shows way bigger deviation. Additional head movement increases error rate and makes controlling more difficult.
The goal of simulations in computergraphics is the simulation of realistic phenomena of materials. Therefore, internal and external acting forces are accumulated in each timestep. From those, new velocities get calculated that ultimately change the positions of geometry or particles. Position Based Dynamics omits thie velocity layer and directly works on the positions. Constraints are a set of rules defining the simulated material. Those rules must not be violated throughout the simulation. If this happens, the violating positions get changed so that the constraints get fullfilled once again. In this work a PBD-framework gets implemented, that allows simulations of solids and fluids. Constraints get solved using GPU implementations of Gauss-Seidel and Gauss-Jakobi solvers. Results are physically plausible simulations that are real-time capable.
Es wird ein Augmented-Reality Ansatz zur Erforschung modularer OSGi-Softwaresysteme präsentiert. Der Prototyp wird unter der Verwendung der Microsoft HoloLens implementiert. Module, wie Komponenten und Packages, werden in einer virtuellen Stadt dargestellt. Dieser Ansatz ermöglicht es dem Anwender, die Software-Architektur mittels intuitiver Navigation zu erkunden: Spracheingabe, Blickpunkt- und Gestenkontrolle. Eine multifunktionale Benutzeroberfläche wird vorgestellt, die für verschiedene Zielgruppen adaptiert werden kann. Viele veröffentlichte Visualisierungen weisen keine klare Zielgruppendefinition auf. Das Konzept kann leicht auf andere Darstellungsformen, wie beispielsweise der Inselmetapher übertragen werden. Erste Ergebnisse einer Evaluierung, die mittels kleiner strukturierter Interviews gewonnen werden konnten, werden präsentiert. Die Probanden mussten vier Programm-verständnis Aufgaben lösen und ihren Aufwand, sowie ihre Arbeitsbelastung einschätzen. Die Ergebnisse bilden eine gute Grundlage für weitere Forschung im Bereich der Software- Visualisierung in Augmented Reality.
The mitral valve is one of the four valves in the human heart. It is located in the left heart chamber and its function is to control the blood flow from the left atrium to the left ventricle. Pathologies can lead to malfunctions of the valve so that blood can flow back to the atrium. Patients with a faulty mitral valve function may suffer from fatigue and chest pain. The functionality can be surgically restored, which is often a long and exhaustive intervention. Thorough planning is necessary to ensure a safe and effective surgery. This can be supported by creating pre-operative segmentations of the mitral valve. A post-operative analysis can determine the success of an intervention. This work will combine existing and new ideas to propose a new approach to (semi-)automatically create such valve models. The manual part can guarantee a high quality model and reliability, whereas the automatic part contributes to saving valuable labour time.
The main contributions of the automatic algorithm are an estimated semantic separation of the two leaflets of the mitral valve and an optimization process that is capable of finding a coaptation-line and -area between the leaflets. The segmentation method can perform a fully automatic segmentation of the mitral leaflets if the annulus ring is already given. The intermediate steps of this process will be integrated into a manual segmentation method so a user can guide the whole procedure. The quality of the valve models generated by the method proposed in this work will be measured by comparing them to completely manually segmented models. This will show that commonly used methods to measure the quality of a segmentation are too general and do not suffice to reflect the real quality of a model. Consequently the work at hand will introduce a set of measurements that can qualify a mitral valve segmentation in more detail and with respect to anatomical landmarks. Besides the intra-operative support for a surgeon, a segmented mitral valve provides additional benefits. The ability to patient-specifically obtain and objectively describe the valve anatomy may be the base for future medical research in this field and automation allows to process large data sets with reduced expert dependency. Further, simulation methods that use the segmented models as input may predict the outcome of a surgery.
Object recognition is a well-investigated area in image-based computer vision and several methods have been developed. Approaches based on Implicit Shape Models have recently become popular for recognizing objects in 2D images, which separate objects into fundamental visual object parts and spatial relationships between the individual parts. This knowledge is then used to identify unknown object instances. However, since the emergence of aσordable depth cameras like Microsoft Kinect, recognizing unknown objects in 3D point clouds has become an increasingly important task. In the context of indoor robot vision, an algorithm is developed that extends existing methods based on Implicit Shape Model approaches to the task of 3D object recognition.
Stylized image triangulation
(2019)
Stylized image triangulation is a popular tool of image processing. Results can be found on magazine covers or bought as a piece of art. Common use cases are filters by mobile apps or programs dedicated to automated triangulation. This thesis is based upon a paper that achieves new results formulating the adaptive dynamic triangulation as optimization problem. With this approach, new results concerning visual and technical quality are accomplished. One aim of this thesis is to make this approach accessible to as many users as possible. To reach users, a mobile app called Mesh is designed and implemented. A client-host-system is presented which relieves the app from computing the result requiring a lot of resources. Therefore, transferring the approach to a CPU based solution is part of the thesis. Also, a webserver is implemented that handles the communication between app and algorithm. “Mesh” enables the user to send a arbitrary image to the server whose result can be downloaded.
Part of the research deals with optimizing the method. As the main step, the gradient descent method, which minimizes an approximation error, is examined with three different approaches re-defining the movement of a point: The limitation of the directions of movement in a meaningful manner, diagonal directions and a dynamically repositioning of points are analyzed. Results show no improvement of visual quality using diagonal instead of horizontal and vertical steps. Disallowing a point to take its last position, the limitation of step opportunities results in a loss of visual quality but reaches an intended global error earlier. The dynamically repositioning rests upon a vectorbased solution that weights the directions and applies a factor to each of them. This results in a longer computational time but also in a higher visual quality.
Inspired by the work of Josh Bryan, another part of research aims at imitating an artists style. With the use of pseudo-random events combined with a geometryshader, a more natural look shall be achieved. This method illustrates a way of adding minor details to a rendering. To imitate an artist's work, a more complex and more precise triangulation is needed. As the last aspect, a renderstyle is presented. The style uses a center for its effect moving the triangles of a triangulation apart. The arbitrary choice of placing the centrum enables the renderstyle to be used in animations.
In this master's thesis the principle of hybrid ray tracing, consisting of a rasterization pipeline which includes ray tracing techniques for certain effects, is explained and the implementation of an application which uses a hybrid approach in which ray tracing is used to calculate shadows, ambient occlusion, and reflections and combines those with direct lighting is documented and explained. Hybrid ray tracing is based on the idea of combining the performance and flexibility of rasterization-based approaches with ray tracing to overcome the limitation of not being able to access the complete surrounding geometry at any point in the scene.
While describing the implementation of said application, the RTX API which is being used for ray tracing is explained as well Vulkan, the graphics API used.
Based on the results and the insights gained while using the RTX API, it is assessed in regards of its usage scenarios and technical sophistication.
In recent years head mounted displays (HMD) and their abilities to create virtual realities comparable with the real world moved more into the focus of press coverage and consumers. The reason for this lies in constant improvements in available computing power, miniaturisation of components as well as the constantly shrinking power consumption. These trends originate in the general technical progress driven by advancements made in smartphone sector. This gives more people than ever access to the required components to create these virtual realities. However at the same time there is only limited research which uses the current generation of HMDs especially when comparing the virtual and real world against each other. The approach of this thesis is to look into the process of navigating both real and virtual spaces while using modern hardware and software. One of the key areas are the spatial and peripheral perception without which it would be difficult to navigate a given space. The influence of prior real and virtual experiences on these will be another key aspect. The final area of focus is the influence on the emotional state and how it compares to the real world. To research these influences a experiment using the Oculus Rift DK2 HMD will be held in which subjects will be guided through a real space as well as a virtual model of it. Data will be gather in a quantitative manner by using surveys. Finally, the findings will be discussed based on a statistical evaluation. During these tests the different perception of distances and room size will the compared and how they change based on the current reality. Furthermore, the influence of prior spatial activities both in the real and the virtual world will looked into. Lastly, it will be checked how real these virtual worlds are and if they are sufficiently sophisticated to trigger the same emotional responses as the real world.
The market for virtual reality is rapidly evolving regarding its hardware components. Further applications are the result of this progress. In addition to the gaming market virtual reality offers further possibilities and advantages in research. That way this technology provides the investigation of perceptual phenomena. Therefore the present thesis aimed to examine the induced roelofs effect in a virtual environment and in reality in front of a computer screen. The roelofs effect describes a misperception that occurs if a persons midline and a target surrounding frame are offset, which results in a false localisation of the object. Thus the present study provides insight into the influence of a computer screen regarding this effect. Moreover, conclusions concerning the suitability of virtual reality in perceptual research are drawn. The results obtained by the virtual reality indicated a greater degree of perceptual distortion. Therefore the fixed frame of the computer screen can be assumed as an additional orientation.
The Material Point Method (MPM) has proven to be a very capable simulation method in computer graphics that is able to model materials that were previously very challenging to animate [1, 2]. Apart from simulating singular materials, the simulation of multiple materials that interact with each other introduces new challenges. This is the focus of this thesis. It will be shown that the self-collision capabilities of the MPM can naturally handle multiple materials interacting in the same scene on a collision basis, even if the materials use distinct constitutive models. This is then extended by porous interaction of materials as in[3], which also integrates easily with MPM.It will furthermore be shown that regular single-grid MPM can be viewed as a subset of this multi-grid approach, meaning that its behavior can also be achieved if multiple grids are used. The porous interaction is generalized to arbitrary materials and freely changeable material interaction terms, yielding a flexible, user-controllable framework that is independent of specific constitutive models. The framework is implemented on the GPU in a straightforward and simple way and takes advantage of the rasterization pipeline to resolve write-conflicts, resulting in a portable implementation with wide hardware support, unlike other approaches such as [4].
Diese Arbeit soll das von Dietz und Oppermann entwickelte Planspiel „Datenschutz 2.0“ an den heutigen Alltag der Schüler anpassen, die Benutzung in der Sekundarstufe II ermöglichen und die technischen und gesetzlichen Problematiken des Planspiels beheben. Das mit dem Planspiel aufgegriffene Thema Datenschutz ist im rheinland-pfälzischen Informatik-Lehrplan für die Sekundarstufe II verankert. Hier wird der Begriff Datenschutz in der Reihe „Datenerhebung unter dem Aspekt Datenschutz beurteilen“ genannt. Jedoch werden in dem Planspiel keine Daten erhoben, sondern die selbst hinterlassenen Datenspuren untersucht. Diese Form des Datenschutzes ist im Grundkurs in der vorgeschlagenen Reihe „Datensicherheit unter der Berücksichtigung kryptologischer Verfahren erklären und beachten“ unter dem Thema Kommunikation in Rechnernetzen zu finden. Im Leistungskurs steht die Datensicherheit in gleichbenannter Reihe und Thema und in der Reihe „Datenerhebung unter dem Aspekt Datenschutz beurteilen“ im Thema Wechselwirkung zwischen Informatiksysteme, Individuum und Gesellschaft.
Tracking is an integral part of many modern applications, especially in areas like autonomous systems and Augmented Reality. For performing tracking there are a wide array of approaches. One that has become a subject of research just recently is the utilization of Neural Networks. In the scope of this master thesis an application will be developed which uses such a Neural Network for the tracking process. This also requires the creation of training data as well as the creation and training of a Neural Network. Subsequently the usage of Neural Networks for tracking will be analyzed and evaluated. This includes several aspects. The quality of the tracking for different degrees of freedom will be checked as well as the the impact of the Neural Network on the applications performance. Additionally the amount of required training data is investigated, the influence of the network architecture and the importance of providing depth data as part of the networks input. This should provide an insight into how relevant this approach could be for its adoption in future products.
Constituent parsing attempts to extract syntactic structure from a sentence. These parsing systems are helpful in many NLP applications such as grammar checking, question answering, and information extraction. This thesis work is about implementing a constituent parser for German language using neural networks. Over the past, recurrent neural networks have been used in building a parser and also many NLP applications. In this, self-attention neural network modules are used intensively to understand sentences effectively. With multilayered self-attention networks, constituent parsing achieves 93.68% F1 score. This is improved even further by using both character and word embeddings as a representation of the input. An F1 score of 94.10% was the best achieved by constituent parser using only the dataset provided. With the help of external datasets such as German Wikipedia, pre-trained ELMo models are used along with self-attention networks achieving 95.87% F1 score.
While Virtual Reality has been around for decades it gained new life in recent years. The release of the first consumer hardware devices allows fully immersive and affordable VR for the user at home. This availability lead to a new focus of research on technical problems as well as psychological effects. The concepts of presence, describing the feeling of being in the virtual place, body ownership and their impact are central topics in research for a long time and still not fully understood.
To enable further research in the area of Mixed Reality, we want to introduce a framework that integrates the users body and surroundings inside a visual coherent virtual environment. As one of two main aspects we want to merge real and virtual objects to a shared environment in a way such that they are no longer visually distinguishable. To achieve this the main focus is not supposed to be on a high graphical fidelity but on a simplified representation of reality. The essential question is, what level of visual realism is necessary to create a believable mixed reality environment that induces a sense of presence in the user? The second aspect considers the integration of virtual persons. Can characters be recorded and replayed in a way such that they are perceived as believable entities of the world and therefore act as a part of the users environment?
The purpose of this thesis was the development of a framework called Mixed Reality Embodiment Platform. This inital system implements fundamental functionalities to be used as a basis for future extensions to the framework. We also provide a first application that enables user studies to evaluate the framework and contribute to aforementioned research questions.
The goal of this thesis is to create and develop a concept for a mobile city guide combined with game-based contents.
The application is intented to support flexible and independent exploration of the city of Koblenz.
Based on the geographical data, historical information for and interesting stories of various places were provided in this application. These informations are combined with playful elements in order to create a motivating concept.
Therefore, related approaches were examined and, combined with own ideas, a new concept has been developed. This concept has been prototypically implemented as an Android application and afterwards evaluated by 15 test persons. A questionnaire was used to examine the operability, the motivation of game patterns and the additional value of the application.
Artificial neural networks is a popular field of research in artificial intelli-
gence. The increasing size and complexity of huge models entail certain
problems. The lack of transparency of the inner workings of a neural net-
work makes it difficult to choose efficient architectures for different tasks.
It proves to be challenging to solve these problems, and with a lack of in-
sightful representations of neural networks, this state of affairs becomes
entrenched. With these difficulties in mind a novel 3D visualization tech-
nique is introduced. Attributes for trained neural networks are estimated
by utilizing established methods from the area of neural network optimiza-
tion. Batch normalization is used with fine-tuning and feature extraction to
estimate the importance of different parts of the neural network. A combi-
nation of the importance values with various methods like edge bundling,
ray tracing, 3D impostor and a special transparency technique results in a
3D model representing a neural network. The validity of the extracted im-
portance estimations is demonstrated and the potential of the developed
visualization is explored.
A gonioreflectometer is a device to measure the reflection properties of arbitrary materials. In this work, such an apparatus is being built from easily obtainable parts. Therefore three stepper-motors and 809 light-emitting diodes are controlled by an Arduino microcontroller. RGB-images are captured with an industrial camera which serve as refelction data. Furthermore, a control software with several capture programs and a renderer for displaying the measured materials are implemented. These allow capturing and rendering entire bidirectional reflection distribution functions (BRDFs) by which also complex anisotropic material properties can be represented. Although the quality of the results has some artifacts due to shadows of the camera, these artifacts can be largely removed by using special algorithms like inpainting. In addition, the goniorefelctometer is applied to other use cases. One can perform 3D scans, light field capturing and light staging without altering the construction. The quality of these processes also meet the expectations in a positive way. Thus, the gonioreflectometer built in this work can be seen as a widely applicable and economical alternative to other publications.
In this thesis, the performance of the IceCube projects photon propagation
code (clsim) is optimized. The process of GPU code analysis and perfor-
mance optimization is described in detail. When run on the same hard-
ware, the new version achieves a speedup of about 3x over the original
implementation. Comparing the unmodified code on hardware currently
used by IceCube (NVIDIA GTX 1080) against the optimized version run on
a recent GPU (NVIDIA A100) a speedup of about 9.23x is observed. All
changes made to the code are shown and their performance impact as well
as the implications for simulation accuracy are discussed individually.
The approach taken for optimization is then generalized into a recipe.
Programmers can use it as a guide, when approaching large and complex
GPU programs. In addition, the per warp job-queue, a design pattern used
for load balancing among threads in a CUDA thread block, is discussed in
detail.
Point Rendering
(2021)
In this thesis different methods for rendering point data are shown and compared with each other. The methods can be divided into two categories. For one visual methods are introduced that strictly deal with the displaying of point primitves. The main problem here lies in the depiction of surfaces since point data, unlike traditional triangle meshes, doesn't contain any connectivity information. On the other hand data strucutres are shown that enable real-time rendering of large point clouds. Point clouds often contain large amounts of data since they are mostly generated through 3D scanning processes such as laser scanning and photogrammetry.
Tractography on HARDI data
(2011)
Diffusion weighted imaging is an important modality in clinical imaging and the only possibility to gain insight into the human brain noninvasively and in-vivo. The applications of this imaging technique are diversified. It is used to study the brain, its structure, development and the functionality of the different areas. Further, important fields of application are neurosurgical planning, examinations of pathologies, investigation of Alzheimer-, strokes, and multiple sclerosis. This thesis gives a brief introduction to MRI and diffusion MRI. Based on this, the mostly used data representation in diffusion MRI in clinical imaging, the diffusion tensor, is introduced. As the diffusion tensor suffers from severe limitations new techniques subsumed under the term HARDI (high angular resolution diffusion imaging) are introduced and discussed in detail. Further, an extensive introduction to tractography, approaches that aim at reconstructing neuronal fibers, is given. Based on the knowledge fromthe theoretical part established tractography algorithms are redesigned to handle HARDI data and, thus, improve the reconstruction of neuronal fibers. Among these algorithms, a novel approach is presented that successfully reconstructs fibers on phantom data as well as on human brain data. Further, a novel global classification approach is presented to cluster voxels according to their diffusion properties.
Die Medizinische Visualisierung komplexer Gefäßbäume hat das Potential den klinischen Alltag in der Gefäßchirurgie zu erleichtern.
Dazu sind exakte, hochaufgelöste Darstellungen und echtzeitfähige Berechnungsmethoden notwendig. Bekannte Ansätze aus den Bereichen der direkten (z.B. Raycasting) und indirekten
(z.B. Marching Cubes) Volumenvisualisierung sind nicht in der Lage alle Anforderungen zufriedenstellend zu erfüllen. Verbesserte
Ergebnisse können mit hybriden Methoden erzielt werden, die unterschiedliche Visualisierungsverfahren kombinieren.
Im Rahmen dieser Arbeit wurde ein hybrides Renderingsystem zur Darstellung von Blutgefäßen entwickelt, das die Bildqualität durch Integration einer Marching Cubes Oberfläche in ein Raycasting–System optimiert, dabei Detailstrukturen erhält und ausreichende Performanz zur Interaktion bietet. Die Ergebnissezeigen die verbesserte Plastizität und Genauigkeit der Darstellung.Anhand von Experten– und Laienbefragungen konnte der Nutzen des Systems vor allem für die Patientenaufklärung nachgewiesen werden. Die Erschließung zusätzlicher Anwendungsgebiete ist durch die Weiterentwicklung des Renderers möglich.
This master- thesis investigates the topic of intercultural web design. Two websites from different countries are exemplarily compared. On the basis of cultural dimensions, cultural differences are presented on each respective website. The analysis particularly focuses on how detailed the respective website-designer and -operator regards their users" cultural differences and the creation of a cross-cultural web design. The analysis illustrates which cultural - and particularly intercultural - aspects of countries were taken into consideration in the design of the web sites. The investigation led to the conclusion that their implementation was not consequently executed for all web sites. Hence, this thesis offers suggestions for the improvement of aspects which are most important in intercultural web design.
Unterschiedliche Quellen (Print-Medien, Fernsehberichte u. Ä.) berichten immer wieder davon, dass es mit der Datenschutzkompetenz bei Kindern und Jugendlichen schlecht bestellt ist. Daher ist dem Thema Datenschutz im Informatikunterricht eine besondere Bedeutung zuzuschreiben.
Im Rahmen der Dissertation von Herrn Hug wird ein Datenschutzkompetenzmodell [Quelle INFOS17] entwickelt, anhand dessen die Datenschutzkompetenz von Schülerinnen und Schülern im Altern von 10 bis 13 Jahren gemessen werden kann.
Im Rahmen dieser Masterarbeit werden existierende Unterrichtsmaterialien zum Thema Datenschutz gesammelt und dazu eine Unterrichtsreihe entwickelt. Hierbei werden auch eigene Zugänge aufzeigt, um ein kohärentes und abgeschlossenes Projekt zu entwerfen, bei dem aktuelle Gefahren für Schülerinnen und Schüler aufgezeigt werden. Ziel ist es, dass die Schülerinnen und Schüler dazu befähigt werden, ihr Verhalten bezüglich Datenschutz besser einzuschätzen und verantwortungsvoller mit ihren persönlichen Daten umzugehen. Im Rahmen eines Feldversuches in einer 6. Klasse eines Gymnasiums wurde die Unterrichtsreihe erprobt.
Since the invention of U-net architecture in 2015, convolutional networks based on its encoder-decoder approach significantly improved results in image analysis challenges. It has been proven that such architectures can also be successfully applied in different domains by winning numerous championships in recent years. Also, the transfer learning technique created an opportunity to push state-of-the-art benchmarks to a higher level. Using this approach is beneficial for the medical domain, as collecting datasets is generally a difficult and expensive process.
In this thesis, we address the task of semantic segmentation with Deep Learning and make three main contributions and release experimental results that have practical value for medical imaging.
First, we evaluate the performance of four neural network architectures on the dataset of the cervical spine MRI scans. Second, we use transfer learning from models trained on the Imagenet dataset and compare it to randomly initialized networks. Third, we evaluate models trained on the bias field corrected and raw MRI data. All code to reproduce results is publicly available online.
Mit der Microsoft Kinect waren die ersten Aufnahmen von synchronisierten Farb- und Tiefendaten (RGB-D) möglich, ohne hohe finanzielle Mittel aufwenden zu müssen und neue Möglichkeiten der Forschung eröffneten sich. Mit fortschreitender Technik sind auch mobile Endgeräte in der Lage, immer mehr zu leisten. Lenovo und Asus bieten die ersten kommerziell erwerblichen Geräte mit RGB D-Wahrnehmung an. Mit integrierten Funktionen der Lokalisierung, Umgebungserkennung und Tiefenwahrnehmung durch die Plattform Tango von Google gibt es bereits die ersten Tests in verschiedenen Bereichen des Rechnersehens z.B. Mapping. In dieser Arbeit wird betrachtet, inwiefern sich ein Tango Gerät für die Objekterkennung eignet. Aus den Ausgangsdaten des Tango Geräts werden RGB D-Daten extrahiert und für die Objekterkennung verarbeitet. Es wird ein Überblick über den aktuellen Stand der Forschung und gewisse Grundlagen bezüglich der Tango Plattform gegeben. Dabei werden existierende Ansätze und Methoden für eine Objekterkennung auf mobilen Endgeräten untersucht. Die Implementation der Erkennung wird anhand einer selbst erstellten Datenbank von RGB-D Bildern gelernt und getestet. Neben der Vorstellung der Ergebnisse werden Verbesserungen und Erweiterungen für die Erkennung vorgeschlagen.
Clubs, such as Scouts, rely on the work of their volunteer members, who have a variety of tasks to accomplish. Often there are sudden changes in their organization teams and offices, whereby planning steps are lost and inexperience in planning occurs. Since the special requirements are not covered by already existing tools, ScOuT, a planning tool for the organization administration, is designed and developed in this work to support clubs with regard to the mentioned problems. The focus was on identifying and using various suitable guidelines and heuristic methods to create a usable interface. The developed product was evaluated empirically by a user survey in terms of usability.
The result of this study shows that already a high degree of the desired goal could be reached by the inclusion of the guidelines and methods. From this it can be concluded that with the help of user-specific concept ideas and the application of suitable guidelines and methods, a suitable basis for a usable application to support clubs can be created.
With the appearance of modern virtual reality (VR) headsets on the consumer market, there has been the biggest boom in the history of VR technology. Naturally, this was accompanied by an increasing focus on the problems of current VR hardware. Especially the control in VR has always been a complex topic.
One possible solution is the Leap Motion, a hand tracking device that was initially developed for desktop use, but with the last major software update it can be attached to standard VR headsets. This device allows very precise tracking of the user’s hands and fingers and their replication in the virtual world.
The aim of this work is to design virtual user interfaces that can be operated with the Leap Motion to provide a natural method of interaction between the user and the VR environment. After that, subject tests are performed to evaluate their performance and compare them to traditional VR controllers.