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- Institut für Computervisualistik (100) (remove)
Helicopters are crucial in today’s life. A vast amount of applications prove
their range, which are not coverable by other types of aircraft. But they are
very complex systems, both, technically and physically. This is one of the
reasons why pilot training for helicopters is quite challenging. In the last
two decades flight simulators became a supplementary instrument in the
educational process of pilots. With flight simulators it is possible to replay
uncommon or dangerous situations. In this thesis a simple flight simulator
for helicopters will be developed based on rigid body physics. The foundation is a simplified rotor model which omits complex fluid dynamics. This
helps to keep the implementation simple and illustrative as well as provide simulation rates at real-time. The modules are implemented within
the Unreal Engine in such way, that changing helicopter characteristics is
very easy.
Real-time graphics applications are tending to get more realistic and approximate real world illumination gets more reasonable due to improvement of graphics hardware. Using a wide variation of algorithms and ideas, graphics processing units (GPU) can simulate complex lighting situations rendering computer generated imagery with complicated effects such as shadows, refraction and reflection of light. Particularly, reflections are an improvement of realism, because they make shiny materials, e.g. brushed metals, wet surfaces like puddles or polished floors, appear more realistic and reveal information of their properties such as roughness and reflectance. Moreover, reflections can get more complex, depending on the view: a wet surface like a street during rain for example will reflect lights depending on the distance of the viewer, resulting in more streaky reflection, which will look more stretched, if the viewer is locatedrnfarther away from the light source. This bachelor thesis aims to give an overview of the state-of-the-art in terms of rendering reflections. Understanding light is a basic need to understand reflections and therefore a physical model of light and its reflection will be covered in section 2, followed by the motivational section 2.2, that will give visual appealing examples for reflections from the real world and the media. Coming to rendering techniques, first, the main principle will be explained in section 3 followed by a short general view of a wide variety of approaches that try to generate correct reflections in section 4. This thesis will describe the implementation of three major algorithms, that produce plausible local reflections. Therefore, the developed framework is described in section 5, then three major algorithms will be covered, that are common methods in most current game and graphics engines: Screen space reflections (SSR), parallax-corrected cube mapping (PCCM) and billboard reflections (BBR). After describing their functional principle, they will be analysed of their visual quality and the possibilities of their real-time application. Finally they will be compared to each other to investigate the advantages and disadvantages over each other. In conclusion, the gained experiences will be described by summarizing advantages and disadvantages of each technique and giving suggestions for improvements. A short perspective will be given, trying to create a view of upcoming real-time rendering techniques for the creation of reflections as specular effects.
VR Fresken
(2018)
Das Projekt VR Fresken setzte sich zum Ziel, mit Hilfe von virtueller Realität im Rahmen einer Museumsausstellung historisch rekonstruierte Räume und deren Deckenfresken interaktiv erlebbar zu machen. In dieser Arbeit werden die eingesetzten Techniken und Technologien beleuchtet, der Anwendungsfall der VR für den Einsatz im Museum untersucht, sowie eine Evaluation der Software im Alltagsbetrieb im Museum durchgeführt.
The goal of this work is evaluation and optimization of several eye-tracking algorithms for estimation of relevant features regarding accuracy. The extracted features are pupil- and glintcenters. The algorithms are applicable to off the shelf cameras. A synthetic model of the eye was modified and utilized. The model was used to supply ground truth for the evaluation of the methods.
In order to simulate realistic motion sequences, muscles must be able to be modelled anatomically correct. Yet it is only possible in SimPack to define muscles as a straight line between two points. This thesis presents an approach where ellipses can be defined through which a muscle must pass. The main problem is to calculate the length of this muscle through the ellipses. An algorithm is presented that calculates the shortest path of a muscle path through this ellipses. This algorithm is then implemented in Fortran 90 and integrated into an existing muscle model in SimPack.
Texture-based text detection in digital images using wavelet features and support vector machines
(2010)
In this bachelor thesis a new texture-based approach for the detection of text in digital images is presented. The procedure can be essentially divided into two main tasks, in detection of text blocks and detection of individual words, whereby the individual words are extracted from the detected text blocks. Roughly, the developed method acts with multiple support vector machines, which classify possible text regions of an image into real text regions, using wavelet-based features. In the process the possible text regions are defifined by edge projections with diσerent orientations. The results of the approach are X/Y coordinates, width and height of rectangular regions of an image, which contains individual words. This knowledge can be further processed, for example by an optical character recognition software to get the important and useful text information.
Im Bereich der Computergraphik bilden die Nicht-Photorealistischen Renderingverfahren einen Schwerpunkt in der technischen und wissenschaftlichen Visualisierung, vor allem aber in den künstlerischen Bereichen. Verschiedene Kunststile, sowie Zeichenmaterialien und ihre Eigenschaften stellen unterschiedliche Herausforderungen dar. Eine dieser Herausforderungen ist hierbei die Simulation flüssiger Zeichenmittel.
Diese Arbeit beschäftigt sich mit der Erstellung eines interaktiven Zeichensystems für ein flüssiges Zeichenmittel, der Aquarellmalerei. Für die Simulation wird eine raue Zeichengrundlage generiert, sowie die Fluid Simulation und das optische Farbverhalten der Aquarellmalerei implementiert.
Augmented Reality has many areas of application. It can be used to simplify everyday life as well as working processes. However, since there are
many manufacturers that offer greatly varying systems, choosing the correct system according to application as well as cross-platform development are dfficult. This thesis attempts to develop an application which can be used to simulate Augmented Reality devices on Virtual Reality systems. This should simplify the processes of choosing a system as well as cross-platform
development.
Since the simulation will be designed to run on mobile devices, it should be possible to render high quality, realistic environments in advance, using a panoramic image. On a Virtual Reality device, they need to be displayed as a stereoscopic image. To achieve this, several methods are presented that can be used to perform this conversion. An editor will be created which will allow the creation of scenes, configuration of Augmented Reality devices and displaying them on a Virtual Reality system. For closing this thesis a test will be performed, to check the quality of the simulation as well as improvements that can be made.
This Bachelor thesis describes the conception, implementation and evaluation of a playful augmented reality application for mobile devices. Building on the ARCore SDK, the game pARcours was developed, where the player can place virtual objects in the real environment to build their own parcours. This must be flown through with a likewise virtual aircraft. The main focus in the implementation of the game was on the interaction with the virtual objects and the collision detection of these with real surfaces. Furthermore, various input methods for building the parcours and controlling the aircrafts were examined. In a final evaluation both the game and the various input methods could be evaluated, as well as ARCore with regard to the development of augmented reality applications.
This thesis deals with the development of an authoring system for modeling 3D environments with physical description. In contrast to creating scenes in other common modeling tools, one can now compute and describe physical entities of a scene additional to the usual geometry. It is very important for those authoring systems to be extendable and customizable for specific requirement of the user. The focus lies on developing simple program architecture, which is easy to extend and to modify.
A special challenge of the basic musical education of children is to give them an understanding of reading and writing musical scores. During the training of young choristers it is furthermore important to educate them in directly transforming the written scores into sounds.
Therefore it is an interesting idea to play the sounds to the children via piano or keyboard and simultaneously present them on a screen in musical notation.
The aim of this bachelor thesis is the implementation of such a system that allows to enter scores using a MIDI-compatible keyboard and then depicting these as musical notation. The prototype of the application operates in three steps. It receives the musical scores via keyboard in form of MIDIdatasets. These MIDI-information are converted to the MusicXML-format. Based on this MusicXML-notation the software finally generates and displays the visual output.
This thesis presents two methods for the computation of global illumination. The first is an extension of Reflective Shadow Maps with an additional shadow test in order to handle occlusion. The second method is a novel, bidirectional Light-Injection approach. Rays originating from the light source are traced through the scene and stored inside the shafts of the Linespace datastructure. These shafts are a discretization of the possible spatial directions. The Linespaces are embedded in a Uniform Grid. When retrieving this pre-calculated lightning information no traversal of datastructures and no additional indirection is necessary in the best-case scenario. This reduces computation time and variance compared to Pathtracing. Areas that are mostly lit indirectly and glas profit the most from this. However, the result is only approximative in nature and produces visible artifacts.
Der Markt der mobilen Endgeräte entwickelt sich schnell weiter und es kommen schon Kinder im frühsten Alter mit solchen Technologien in Berührung. Daher ist es wichtig, Kinder richtig an die Geräte heranzuführen. Von Vorteil wäre eine Einbindung von Smartphones und Tablets, im Bezug auf den Lernprozess, in den Unterricht. Die vorliegende Arbeit behandelt deshalb das Konzept einer Lernspielapp, die durch Pädagogen konfiguriert werden kann. Die Evaluation soll Aufschluss über die Motivation der Kinder geben und die Aufgeschlossenheit der Pädagogen gegenüber neuen Medien ermitteln.
Ray Tracing enables a close to reality rendering implementation of a modelled scene. Because of its functioning, it is able to display optical phenomena and complex lighting. Though, numerous computations per pixel have to be done. In practice implementations can not achieve computer graphics" aim of real-time rendering close to 60 frames per second. Current Graphics Processing Units (GPU) allows high execution parallelism of general-purpose computations. By using the graphics-API OpenGL this parallelism can be achieved and it is possible to design and realize a Ray-Tracer, which operates entirely on the GPU. The developed approach will be extended by an Uniform Grid - a Ray-Tracing acceleration structure. Hence, a speed-up is expected.
This thesis` purpose is the implementation of Ray-Tracer, which operates completely on the GPU, and its expansion by integrating an Uniform Grid. Afterwards, the evaluation of maximum achievable performance takes place. Possible problems regarding GPU-programming will be identified and analysed.
This work describes a novel software tool for visualizing anatomical segmentations of medical images. It was developed as part of a bachelor's thesis project, with a view to supporting research into automatic anatomical brain image segmentation. The tool builds on a widely-used visualization approach for 3D image volumes, where sections in orthogonal directions are rendered on screen as 2D images. It implements novel display modes that solve common problems with conventional viewer programs. In particular, it features a double-contour display mode to aid the user's spatial orientation in the image, as well as modes for comparing two competing segmentation labels pertaining to one and the same anatomical region. The tool was developed as an extension to an existing open-source software suite for medical image processing. The visualization modes are, however, suitable for implementation in the context of other viewer programs that follow a similar rendering approach.
The modified code can be found here: soundray.org/mm-segmentation-visualization.tar.gz.
Simulation von Schnee
(2015)
Physic simulations allow the creation of dynamic scenes on the computer. Computer generated images become lively and find use in movies, games and engineering applications. GPGPU techniques make use of the graphics card to simulate physics. The simulation of dynamic snow is still little researched. The Material Point Method is the first technique which is capable of showing the dynamics andrncharacteristics of snow.
The hybrid use of Lagrangian particles and a regular cartesian grid enables solving of partial differential equations. Therefore articles are transformed to the grid. The grid velocities can then be updated with the calculation of gradients in an FEM-manner (finite element method). Finally grid node velocities are weight back to the particles to move them across the scene. This method is coupled with a constitutive model to cover the dynamic nature of snow. This include collisions and breaking.
This bachelor thesis connects the recent developments in GPGPU techniques of OpenGL with the Material Point Method to efficiently simulate visually compelling, dynamic snow scenes.
This thesis covers the mathematical background of ray-casting as well as an exemplary implementation on graphics processing units, using a modern programming interface. The implementation is embedded within an editor, which enables the user to activate optimizations of the algorithm. Techniques like transfer functions and local illumination are available for a more realistic visualization of materials. Moreover, the user interface gives access to features like importing volumes, let one define a custom transfer function, holds controls to adjust parameters of rendering and allows to activate further techniques, which are also subject of discussion in this thesis. Benefit of all shown techniques is measured, whether it is expected to be visual or on the part of performance.
In den letzten Jahren ist eine steigende Verbreitung von Touchscreen-Geräten zu verzeichnen. Ihre Bedienung unterscheidet sich grundlegend von der mit Maus und Tastatur. Durch die Eingabe mit Gesten oder mehreren Fingern kann es schwierig sein den Aktionen eines Anderen zu folgen. Probleme entstehen durch die Verdeckung des Bildschirms mit der Eingabehand. Sieht man nur den Bildschirminhalt, zum Beispiel bei einer Videoübertragung, gehen Informationen über die Eingabe verloren.
In dieser Arbeit wird ein System entwickelt, das die kollaborative Arbeit an voneinander entfernten Touchscreen-Geräten verbessern soll. Dazu wird aus den Tiefendaten eines Kinect Sensors eine grafische Repräsentation der Eingabehand erstellt. Durch Einblendung dieser Visualisierung soll es einem Anwender erleichtert werden den Eingaben eines Anwenders zu folgen. Bedienkonzepte, wie zum Beispiel Gesten, sollen dadurch besser vermittelt werden. Außerdem soll so die Möglichkeit geschaffen werden, Informationen über eine gemeinsame Problematik effizienter auszutauschen. Deshalb wurde ein Testsystem mit zwei Arbeitsplätzen entwickelt. Darin übernimmt ein Anwender die Rolle des Erklärenden und führt einen zweiten Anwender, den Ausführenden, durch verschiedene Testszenarien. Hierbei stehen ihm bei einem Teil der Aufgaben die Visualisierung der Hand zur Verfügung, während er in anderen Aufgaben nur verbal mit seinem Gegenüber kommunizieren kann.
Im Rahmen einer Evaluation wird das System auf seine Effizienz zur Bedienung von Touchscreen-Systemen überprüft. Des Weiteren wird untersucht, inwieweit die grafische Qualität den gestellten Anforderungen genügt, um einen Mehrwert für die Anwendung zu bieten.
In this thesis we present an approach to track a RGB-D camera in 6DOF andconstruct 3D maps. We first acquire, register and synchronize RGB and depth images. After preprocessing we extract FAST features and match them between two consecutive frames. By depth projection we regain the z-value for the inlier correspondences. Afterwards we estimate the camera motion by 3D point set alignment between the correspondence set using least-squares. This local motion estimate is incrementally applied to a global transformation. Additionally wernpresent methods to build maps based on point cloud data acquired by a RGB-D camera. For map creation we use the OctoMap framework and optionally create a colored point cloud map. The system is evaluated with the widespread RGB-D benchmark.