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- Institut für Computervisualistik (46) (remove)
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.
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.
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.
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.
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].
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.
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.
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.
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.
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.
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.
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.
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 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#.
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.
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.
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.
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.
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.