Projects

Project partner: Prof. Dr. Michael Kolonko, Clausthal University of Technology

Many materials and substances are made up of particles, from concrete to tablets. Some properties of the finished materials are already strongly determined by the geometric properties of the particle mixtures. In the case of concrete, for example, the volume of the dry mixture, i.e. the ratio of the container size to the volume of the particles contained, is decisive for the strength of the concrete after curing. In other applications, such as the production of foams, the distribution and shape of the spaces between the 'particles', which in this case are cavities, play a decisive role in the properties of the material.

The right choice of mixture composition and particle size distribution is therefore crucial in the development of particle-based materials with specified properties. Until now, this has usually required complex laboratory experiments, but there have been successful attempts to at least simulate the geometry of the mixtures on the computer. The Kolonko working group has been developing a program system "RaSim" for several years, which simulates the random dense arrangement (packing) of a mixture of spherical particles with a specified grain size distribution (KGV). The main area of application is concrete research, where the search is on for KGVs with the highest possible space filling. As a result, the simulation currently provides the achieved space filling as a percentage and creates static images of simulated packings with standard software.

In order to use the simulation in a broader field of application, such as the production of filters and membranes from particles, but also for the production of mixtures for foundry molds or 3D printing, further qualitative properties of the packings must be determined, e.g. concerning the local interaction of the particles. This is particularly necessary when non-spherical particles are simulated, as is already possible to some extent. The aim here is to recognize the relative position of the (differently shaped) particles to each other and to be able to assess the mixing. This would also make it possible to study the effects of individual parameter settings of the simulation, which in turn correspond to real conditions such as pressure or duration of the mixing process, in more detail.

In real mixtures, the arrangement and shape of the gaps can be examined under a microscope, for example, or possible (undesirable) sorting of the particles can be detected. The aim of this project is therefore to develop a flexible visualization tool which, as a kind of virtual microscope, enables intensive qualitative investigations of a simulated mixture. This would extend the range of applications of existing simulation systems and at the same time be an important tool for the further development and improvement of the simulation.

Interactive Visualization of Gaps and Overlaps for Large and Dynamic Sphere Packings
FengGu, Z. Yang, Michael Kolonko, Thorsten Grosch
Vision, Modelling and Visualization (VMV 2017)

Accelerated simulation of sphere packings using parallel hardware
Zhixing Yang, Feng Gu, Thorsten Grosch, Michael Kolonko
Simulation Science (2018)

Fast and Dynamic Construction of Bounding Volume Hierarchies Based on Loose Octrees
FengGu, Johannes Jendersie, Thorsten Grosch
Vision, Modelling and Visualization (VMV 2018)

Accelerating the Visualization of Gaps and Overlaps for Large and Dynamic Sphere Packings with Bounding Volume Hierarchies
FengGu, Zhixing Yang, Michael Kolonko, Thorsten Grosch
Simulation Science (2020)

Visualization and Inspection of the Geometry of Particle Packings
Feng Gu
phd-thesis (2022)

Project partner: Prof. Dr. Raimund Dachselt, TU Dresden

Thanks to mobile devices, augmented reality has the potential to be increasingly used beyond industrial applications in the future. In the field of architecture and interior design, for example, virtual furniture or windows can be placed in real rooms.

In order to manipulate a real world that is as convincingly augmented as possible, photorealistic representations generated in real time as well as natural, seamless forms of interaction with the virtual objects are required. These are two key success factors for augmented reality applications that are being researched in the IPAR project.

The basis is firstly the measurement of the complex, real lighting conditions that are used as input for the real-time illumination of the virtual objects. In addition to changing the real virtual objects, this also enables virtual manipulation of real objects with consistent lighting. On the one hand, indirect techniques are being investigated for the interactions, in which modern tablets held in the hand are used as so-called "magic lenses". Similar to a camera display, they represent a window into the virtually enriched reality through which users can manipulate objects. On the other hand, direct gestural interaction techniques in combination with a mobile projection onto real objects will also be developed and evaluated.

In addition to research questions on measuring and modeling temporally and spatially varying lighting in indoor spaces, the research project is investigating the challenges arising from seamless integration in terms of user interaction and acceptance.