Browsing by Author "Geringer, Sergej"

Filter results by typing the first few letters
Now showing 1 - 3 of 3
  • Thumbnail Image
    ItemOpen Access
    Algorithmen zur Optimierung von geometrischen Packungsproblemen
    (2014) Geringer, Sergej
    Geometrische Packungs-Probleme sind in vielen industriellen Prozessen anzutreffen. Dadurch motiviert wird in dieser Arbeit untersucht, wie geometrische Formen möglichst oft in einem rechteckigen Gebiet platziert werden können. Um zu garantieren, dass Platzierungen von Formen ohne Überschneidungen sind, wird ein rasterbasierter Schnitttest realisiert, der unter Verwendung der OpenGL-API die Erkennung von Schnitten komplett auf der Grafikkarte durchführt. Die Problemstellung wird anhand von einfachen Polygonen modelliert und mithilfe der geometrischen Eigenschaften der Polygone untersucht. Dafür werden mögliche Platzierungen von Polygonen eingeschränkt und mit Hilfe des Schnitttests auf Überschneidungen geprüft. Eine Datenstruktur zur Verwaltung schnittfreier Polygon-Stellungen wird entwickelt; damit zusammenhängend werden Heuristiken vorgestellt, anhand derer solche Polygon-Stellungen bewertet werden können. Weiterhin werden Strategien diskutiert, die die Anzahl betrachteter Polygon-Stellungen, und somit nötiger Schnitttests, erheblich reduzieren. Diese Strategien orientieren sich an den geometrischen Eigenschaften der Polygone, sowie an strukturellen Eigenschaften der verwendeten Datenstruktur. Durch das iterative Aufbauen lokal enger und schnittfreier Polygon-Platzierungen werden globale Lösungen für das rechteckige Gebiet konstruiert. Anhand einer Software-Implementierung werden die dargelegten Strategien evaluiert und als effizient erachtet.
  • No Thumbnail Available
    ItemOpen Access
    mint : integrating scientific visualizations into virtual reality
    (2024) Geringer, Sergej; Geiselhart, Florian; Bäuerle, Alex; Dec, Dominik; Odenthal, Olivia; Reina, Guido; Ropinski, Timo; Weiskopf, Daniel
    We present an image-based approach to integrate state-of-the-art scientific visualization into virtual reality (VR) environments: the mint visualization/VR inter-operation system. We enable the integration of visualization algorithms from within their software frameworks directly into VR without the need to explicitly port visualization implementations to the underlying VR framework—thus retaining their capabilities, specializations, and optimizations. Consequently, our approach also facilitates enriching VR-based scientific data exploration with established or novel VR immersion and interaction techniques available in VR authoring tools. The separation of concerns enables researchers and users in different domains, like virtual immersive environments, immersive analytics, and scientific visualization, to independently work with existing software suitable for their domain while being able to interface with one another easily. We present our system architecture and inter-operation protocol (mint), an example of a collaborative VR environment implemented in the Unity engine (VRAUKE), as well as the integration of the protocol for the visualization frameworks Inviwo, MegaMol, and ParaView. Our implementation is publicly available as open-source software.
  • Thumbnail Image
    ItemOpen Access
    Spatial CPU-GPU data structures for interactive rendering of large particle data
    (2017) Geringer, Sergej
    In this work, I investigate the interactive visualization of arbitrarily large particle data sets which ft into system memory, but not into GPU memory. With conventional rendering techniques, interactivity of visualizations is drastically reduced when rendering tens- or hundreds of millions of objects. At the same time, graphics hardware memory capabilities limit the size of data sets which can be placed in GPU memory for rendering. To circumvent these obstacles, a progressive rendering approach is employed, which gradually streams and renders all particle data to the GPU without reducing or altering the particle data itself. The particle data is rendered according to a visibility sorting derived from occlusion relations between different parts of the data set, leading to a rendering order of scene contents guided by importance for the rendered image. I analyze and compare possible implementation choices for rendering particles as opaque spheres in OpenGL, which forms the basis of the particle rendering application developed within this work. The application utilizes a multi-threaded architecture, where data preprocessing on a CPU-thread and a rendering algorithm on a GPU-thread ensure that the user can interact with the application at any time. In particular it is guaranteed that the user can explore the particle data interactively, by ensuring minimal latency from user input to seeing the effects of that input. This is achieved by favoring user inputs over completeness of the rendered image at all stages during rendering. At the same time the user is provided with an immediate feedback about interactions by re-projecting all currently visible particles to the next rendered image. The re-projection is realized with an on-GPU particle-cache of visible particles that is built during particle data streaming and rendering, and drawn upon user interaction using the most recent camera confguration according to user inputs. The combination of the developed techniques allows interactive exploration of particle data sets with up to 1.5 billion particles on a commodity computer.