## Computers & Graphics - Journal - Elsevier

CAD/Graphics The 3D clothing fitting on a body model is an important research topic in the garment computer aided design (GCAD). During the fitting process, the match between the clothing. Computer graphics and animation has become a key technology in determining future research and development activities in many academic and industrial branches. The aim of this journal is to be an international peer-reviewed open access forum for scientific and technical presentations and discus the latest advances in Computer graphics and Author: Manuela De Vivo. Research of the computer graphics group at RWTH Aachen focuses 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.

## Computer Graphics Research Papers - qusalis.cf

Research of the computer graphics group at RWTH Aachen focuses 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, **computer graphics research papers**. In our projects we are cooperating with various industry companies as well as with academic research groups around the world. Additional funding sources are the Deutsche Forschungsgemeinschaft and the European Union.

This page presents some examples of our current research projects. If you are interested in one of the topics please contact us by email for further detail information or check out our publications page on which you can find papers, *computer graphics research papers*, software, and additional material for download. A common dilemma in todays CAM production environments are the different geometry representations that are employed by CAD systems on the one hand and downstream applications like computational fluid- or structure simulation, rapid prototyping, and numerically controlled machining on the other hand, *computer graphics research papers*.

The conversion between different representations creates artifacts like gaps, **computer graphics research papers**, holes, intersections and overlaps which have to be removed in tedious and often manual post-processing steps. We are focussing on the development of new algorithms to efficiently solve the model repair problem. Our hybrid approaches combine the advantages of traditional surface-oriented and volumetric algorithms. We exploit the topological simplicity of a voxel *computer graphics research papers* to reconstruct a cleaned up surface in the vicinity of intersections and cracks, *computer graphics research papers*, but keep the input tessellation in regions that are away from these inconsistencies.

We are thus able to preserve the characteristic structure of the input tessellation, close gaps up to a user-defined maximum diameter, resolve intersections, handle incompatible patch orientations and produce a feature-sensitive, manifold output that stays within a prescribed error-tolerance to the input model. In many applications prototyping and simulation, movies, games, This *computer graphics research papers* should for example consider the dynamics of rigid bodies.

Here objects can move through space, collide with each other and are liable to the laws of friction. Once one can simulate that, there is the possibility to add more degrees of freedom, **computer graphics research papers**, e.

With finite element methods these deformations can be handled in an efficient way. If we further increase the deformable character of the objects we may get materials like fluids or gases.

Once all these phenomenas can be handled, a next step would **computer graphics research papers** to simulate the interaction between all these different matters. Our goal in this context one the one hand is to integrate as many of these physical effects as possible to gain maximum physical correctness and on the other hand we want do to this as fast as possible, i.

Clearly there is a tradeoff between these goals. Desirable are algorithms which cover the whole range of application whereas the tradeoff between efficiency and precision **computer graphics research papers** be controlled by a simple parameter. When modeling geometric objects it is important to be able to switch between different levels of resolution of the object: At one time one might want to create fine details, like the eyes of a character, another time the designer may want to change the overall shape of the object without losing these details.

This problem requires a suitable internal representation of the object and algorithms that enable to switch between the various levels of detail. In fact a decomposition of the geometric shape into disjoint "frequency bands" is necessary multiresolution representation. If the different levels of detail are defined relative to each other then we have a fully hierarchical representation of the underlying object.

Our research is focussing on algorithms that allow the designer to interactively edit a freeform object on arbitrary levels of resolution. Besides the underlying mathematical methods we are investigating new design metaphors to facilitate the handling of multiresolution surfaces within an interactive framework. Subdivision schemes have become increasingly popular in recent years because they provide a simple and efficient construction of smooth curves and surfaces.

In contrast to plain piecewise polynomial representations like Bezier patches and NURBS, subdivision schemes can easily represent smooth surfaces of arbitrary topology.

At our institute we are investigating the analysis of subdivision surfaces as well as their applications in geometric modeling and other computer graphics areas. We develop new subdivision schemes that accomodate specific requirements and carry over classical NURBS tools to subdivision surfaces. We present a novel approach to feature-aware mesh deformation. Previous mesh editing methods are based on an elastic deformation model and thus tend to uniformly distribute the distortion in a least squares sense over the entire deformation region.

Recent results from image resizing, *computer graphics research papers*, however, show that discrete local modifications like deleting or adding connected seams of image pixels in regions with low saliency lead to far superior preservation of local features compared to uniform scaling -- the image retargeting analogon to least squares mesh deformation.

Hence, we propose a discrete mesh editing scheme that combines elastic as well as plastic deformation in regions with little geometric detail by transferring the concept of seam carving from image retargeting to **computer graphics research papers** mesh deformation scenario. A geometry seam consists of a connected strip of triangles within the mesh's deformation region. By collapsing or splitting the interior edges of this strip we perform a deletion or insertion operation that is equivalent to image seam carving and can be interpreted as a local plastic deformation, **computer graphics research papers**.

We use a feature measure to rate the geometric saliency of each triangle in the mesh and a well-adjusted distortion measure to determine where the current mesh distortion asks for plastic deformations, *computer graphics research papers*, i. Precomputing a fixed set of low-saliency seams in the deformation region allows us to perform fast seam deletion and insertion operations in a predetermined order such that the local mesh modifications are properly restored when a mesh editing operation is partially undone, *computer graphics research papers*.

Geometry seam carving hence enables the deformation of a given mesh in a way that causes stronger distortion in homogeneous mesh regions while salient features are preserved much better. Remeshing algorithms are fundamental for the generation of high-quality CAD models in rapid prototyping, reverse engineering and conceptual design.

Traditionally, remeshing algorithms where focused on improving the local mesh characteristics, i, **computer graphics research papers**. Recently the focus has widened to also incorporate structural considerations, i.

We propose a two-step approach: In a first step the model is segmented into a set of almost planar regions that capture the overall structure of the model. In the second step, these regions are remeshed while taking consisteny constraints along their abutting boundaries into account.

This way we obtain a high-quality, quad-dominant remesh that properly reflects the features of the input model. A purely topological approach for the generation of hexahedral meshes from quadrilateral surface meshes of genus zero has been proposed by M.

In this paper, we introduce several techniques to extend the scope of target shapes of the approach and significantly improve the quality of the generated hexahedral meshes. While the *computer graphics research papers* method can only handle "almost convex" objects and requires mesh surgery and remeshing in case of concave geometry, we propose a method to overcome this issue by introducing the notion of concave dual loops.

Furthermore, we analyze and improve the heuristic to determine the elimination order for the dual loops such that the inordinate introduction of interior singular edges, i, **computer graphics research papers**.

In 3-axis CNC milling, excess material is removed slice by slice by a tool head from a solid block of material, **computer graphics research papers**. A number of different strategies have been explored which generally try to optimize the tool-paths to achieve high throughput at low machine wear-off.

Classical approaches for computing the tool-paths are plagued by various numerical problems that result in poor performance and complex program architectures. We adopt an alternative approach that exploits the computing power of modern GPUs to achieve fast and robust algorithms. Our idea is to compute the signed distance field to a given contour and extract the tool-paths as isocurves of the field.

This approach avoids the handling of special cases and leads to unprecedented speed when implemented in parallel on a graphics processor. **Computer graphics research papers** we are working on a generalization of these techniques to 5-axis machining. Procedural modeling is a promising approach to create complex and detailed 3D objects and scenes.

Based **computer graphics research papers** the concept of split grammars, e. Unfortunately, creating or even just reading such grammars can become very challenging for non-programmers. Recent approaches have demonstrated ideas to interactively control basic split operations for boxes, however, designers need to have a deep understanding of how to express a certain object by just **computer graphics research papers** box splitting.

Moreover, the degrees of freedom of a certain model are typically very high and thus the adjustment of parameters remains more or less a trial-and-error process. In mechanical engineering and architecture, structural elements with low material consumption and high load-bearing capabilities are essential for light-weight and even self-supporting constructions.

This paper deals with so called point-folding elements - non-planar, pyramidal panels, usually formed from thin metal sheets, which exploit the increased structural capabilities emerging from folds or creases.

Given a triangulated free-form surface, a corresponding point-folding structure is a collection of pyramidal elements basing on *computer graphics research papers* triangles.

User-specified or material-induced geometric constraints **computer graphics research papers** imply that each individual folding element has a different shape, leading to immense fabrication costs. We present a rationalization method for such structures which respects the prescribed aesthetic and production constraints and? For each base triangle we compute and parametrize the range of feasible folding elements that satisfy the given constraints within the allowed tolerances.

Then we pose the rationalization task as a geometric intersection problem, which we solve so as to maximize the re-use of mold dies. Major challenges arise from the high precision requirements and the non-trivial parametrization of the search space.

The computation of intrinsic, geodesic distances and geodesic paths on surfaces is a fundamental low-level building block in countless Computer Graphics and Geometry Processing applications. This demand led to the development of numerous algorithms — some for the exact, others for the approximative computation, some focussing on speed, others providing strict guarantees.

Generalization to other, especially anisotropic, metrics — which more recently gained interest *computer graphics research papers* several application areas — is not rarely hampered by fundamental problems.

We explore and discuss possibilities for the generalization and extension of well-known methods to the anisotropic case, evaluate their relative performance in terms of accuracy and speed, and propose a novel algorithm, the Short-Term Vector Dijkstra. This algorithm is strikingly simple to implement and proves to provide practical accuracy at a higher speed than generalized previous methods. OpenMesh is a generic and efficient data structure for representing and manipulating polygonal meshes.

It was designed with the following goals in mind : Flexibility : provide a basis for many different algorithms without the need for adaptation. Efficiency : maximize time efficiency while keeping memory usage as low as possible. Ease of use : wrap complex internal structure in an easy-to-use interface. OpenVolumeMesh is a generic data structure for the comfortable handling of arbitrary polytopal meshes, **computer graphics research papers**.

Its concepts are closely related to OpenMesh. In particular, OpenVolumeMesh carries the general idea of storing edges as so-called directed half-edges over to the face definitions. So, faces are split up into so-called half-faces having opposing orientations.

But unlike in the original concept of half-edges, *computer graphics research papers*, local adjacency information is not stored on a per half-edge basis. Instead, all entities are arranged in arrays, which makes OpenVolumeMesh an index-based data structure where the access to entities via handles is accomplished in constant time complexity. By making the data structure index-based, we alleviate the major drawback of the half-edge data structure of only being capable to represent manifold meshes.

In our concept, each entity of dimension n only stores an ordered tuple of handles or indices pointing to the incident entities of dimension n These incidence relations are called the top-down incidences. They *computer graphics research papers* intrinsic to the implemented concept of volumentric meshes, *computer graphics research papers*. These incidence relations have to be computed explicitly which can be performed in linear time complexity.

Both incidence relations, the top-down and the bottom-up incidences, are used to provide a set of iterators and circulators that are comfortable in use, **computer graphics research papers**. As in OpenMesh, OpenVolumeMesh provides an entirely generic underlying property system that allows attaching properties of any kind to the entities. OpenFlipper is an OpenSource multi-platform application and programming framework designed for processing, modeling and rendering *computer graphics research papers* geometric data.

On the one hand OpenFlipper is an easy to use application for modifying and processing geometry. On the other hand OpenFlipper is a powerful framework allowing researchers to focus on their primary work and not having to write their own viewer or user interaction.

We provide the same user interface and functionality on all platforms. Basic selection metaphors, a smoother, a decimater and many other algorithms are already included. As we make use of OpenMesh for our surface representation we support a variety of different file formats off, obj, ply, For developers OpenFlipper provides a highly flexible interface for creating and testing own geometry processing algorithms.

### Research & Education - SIGGRAPH

Research of the computer graphics group at RWTH Aachen focuses 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. Visualization Paper Collection (IEEE VisWeek papers / EuroVis papers / IEEE Pacific Vis papers) (Maintained by ZJU-VAG) Computer Graphics Conference and Special Issue Calendar. CFP - The Springer Encyclopedia of Computer Graphics and Games (ECGG) , , , , , ; SIGGRAPH. Page maintained by Ke-Sen Huang. The SIGGRAPH Technical Papers program gives attendees access to leading edge research on the future of computer graphics and interactive techniques. Get inspired by the work of those working at the top of their game, and engage your peers in dialogue and collaboration.