Welcome



Welcome to the Computer Graphics Group at RWTH Aachen University!

The research and teaching activities at our institute focus on geometry acquisition and processing, on interactive visualization, and on related areas such as computer vision, photo-realistic image synthesis, and ultra high speed multimedia data transmission.

In our projects we are cooperating with various industry companies as well as with academic research groups around the world. Results are published and presented at high-profile conferences and symposia. Additional funding sources, among others, are the Deutsche Forschungsgemeinschaft and the European Union.

News

Prof. Dr. Leif Kobbelt gave a talk at the FutureLab Gala in Aachen.

Prof. Dr. Leif Kobbelt gave a talk at the FutureLab Gala in Aachen on why understanding the Pythagorean Theorem is „enough" to run the entire reconstruction pipeline for highly detailed textured 3D models of real objects and scenes.

May 11, 2016

Prof. Dr. Leif Kobbelt received his certificate of appointment from the North Rhine-Westphalian Academy of Sciences, Humanities and the Arts at the annual ceremony in Düsseldorf.

(Link)

May 11, 2016

Dr. Marcel Campen received the Eurographics PhD Award 2016 at Eurographics in Lisbon. (Link)

May 9, 2016

Prof. Dr. Leif Kobbelt has been elected a full member of the North Rhine-Westphalian Academy of Sciences, Humanities and the Arts

The North Rhine-Westphalian Academy of Sciences, Humanities and the Arts is an association of the leading scientists in North Rhine-Westphalia. The Academy was founded in 1970 as the successor institution to the Arbeitsgemeinschaft für Forschung of the Federal State of North Rhine-Westphalia, which had been founded in 1950 by the then Premier of the Federal State, Karl Arnold, to provide advice to the State Government in the reconstruction of the State after its devastation in the war. For further information about the Academy, please visit its homepage.

March 30, 2016

We have a paper on Improved Surface Quality in 3D Printing by Optimizing the Printing Direction at Eurographics 2016.

Feb. 18, 2016

We have a paper on Adapting Feature Curve Networks to a Prescribed Scale at Eurographics 2016.

Feb. 16, 2016

Recent Publications

Non-Linear Shape Optimization Using Local Subspace Projections

SIGGRAPH 2016

In this paper we present a novel method for non-linear shape opti- mization of 3d objects given by their surface representation. Our method takes advantage of the fact that various shape properties of interest give rise to underdetermined design spaces implying the existence of many good solutions. Our algorithm exploits this by performing iterative projections of the problem to local subspaces where it can be solved much more efficiently using standard numer- ical routines. We demonstrate how this approach can be utilized for various shape optimization tasks using different shape parameteri- zations. In particular, we show how to efficiently optimize natural frequencies, mass properties, as well as the structural yield strength of a solid body. Our method is flexible, easy to implement, and very fast.

 

HexEx: Robust Hexahedral Mesh Extraction

SIGGRAPH 2016

State-of-the-art hex meshing algorithms consist of three steps: Frame-field design, parametrization generation, and mesh extraction. However, while the first two steps are usually discussed in detail, the last step is often not well studied. In this paper, we fully concentrate on reliable mesh extraction. Parametrization methods employ computationally expensive countermeasures to avoid mapping input tetrahedra to degenerate or flipped tetrahedra in the parameter domain because such a parametrization does not define a proper hexahedral mesh. Nevertheless, there is no known technique that can guarantee the complete absence of such artifacts. We tackle this problem from the other side by developing a mesh extraction algorithm which is extremely robust against typical imperfections in the parametrization. First, a sanitization process cleans up numerical inconsistencies of the parameter values caused by limited precision solvers and floating-point number representation. On the sanitized parametrization, we extract vertices and so-called darts based on intersections of the integer grid with the parametric image of the tetrahedral mesh. The darts are reliably interconnected by tracing within the parametrization and thus define the topology of the hexahedral mesh. In a postprocessing step, we let certain pairs of darts cancel each other, counteracting the effect of flipped regions of the parametrization. With this strategy, our algorithm is able to robustly extract hexahedral meshes from imperfect parametrizations which previously would have been considered defective. The algorithm will be published as an open source library.

 

Quantized Global Parametrization

SIGGRAPH Asia 2015

Global surface parametrization often requires the use of cuts or charts due to non-trivial topology. In recent years a focus has been on so-called seamless parametrizations, where the transition functions across the cuts are rigid transformations with a rotation about some multiple of 90 degrees. Of particular interest, e.g. for quadrilateral meshing, paneling, or texturing, are those instances where in addition the translational part of these transitions is integral (or more generally: quantized). We show that finding not even the optimal, but just an arbitrary valid quantization (one that does not imply parametric degeneracies), is a complex combinatorial problem. We present a novel method that allows us to solve it, i.e. to find valid as well as good quality quantizations. It is based on an original approach to quickly construct solutions to linear Diophantine equation systems, exploiting the specific geometric nature of the parametrization problem. We thereby largely outperform the state-of-the-art, sometimes by several orders of magnitude.

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