An authoring framework for interactive narrative with virtual characters (2008)
Iurgel, I., Alexa, M., Marcos, A.
Im Forschungsgebiet "interaktive Geschichten" stellt der Erstellungsprozess einen entscheidenden Engpass dar, der die Entwicklung dieses Gebiets derzeit behindert. Ein Grund hierfür ist...
Anisotropic point set surfaces (2006)
Point Set Surfaces define smooth surfaces from regular samples based on weighted averaging of the points. Because weighting is done based on a spatial scale parameter, point set surfaces apply...
Hildenbrand, D., Fontijne, D., Wang, Y., Alexa, M., Dorst, L.
Conformal geometric algebra is a powerful tool to find geometrically intuitive solutions. We present an approach for the combination of compact and elegant algorithms with the generation of very...
Point-sampled cell complexes (2006)
A piecewise smooth surface, possibly with boundaries, sharp edges, corners, or other features is defined by a set of samples. The basic idea is to model surface patches, curve segments and points...
Avalon: Ein skalierbares Rahmensystem für dynamische Mixed-Reality Anwendungen (2006)
Behr, J., Alexa, M., Fröhlich, B.
One of the main contributions of this work is a novel extension of the scene-graph concept. On basis of the scene graph structure a homogeneous model of graphs has been developed allowing to model...
Anisotropic point set surfaces (2006)
Point Set Surfaces define smooth surfaces from regular samples based on weighted averaging of the points. Because weighting is done based on a spatial scale parameter, point set surfaces apply...
Non-conforming surface representations (2005)
Surface geometry is commonly represented by a collection of primitives. Conforming representations consist of primitives meeting at their boundaries (e.g., in a triangle mesh two triangles are...
Ohtake, Y., Belyaev, A., Alexa, M.
We propose a new surface representation delivering an accurate approximation to a set of points scattered over a smooth surface by Sparse Low-degree IMplicits (SLIM). The SLIM surface representation...
Adaptive sampling of intersectable models exploiting image and object-space coherence (2005)
Adamson, A., Alexa, M., Nealen, A.
We present a sampling strategy and rendering framework for intersectable models, whose surface is implicitly defined by a black box intersection test that provides the location and normal of the...
A sketch-based interface for detail-preserving esh editing (2005)
Nealen, A., Sorkine, O., Alexa, M., Cohen-Or, D.
In this paper we present a method for the intuitive editing of surface meshes by means of view-dependent sketching. In most existing shape deformation work, editing is carried out by selecting and...
Alexa, M., Angelidis, A., Singh, K., Zorin, D.
The course will present the state-of-the-art in digigtal modeling techniques, both in commercial software and academic research. The goal of this course is to impart the audience with an...
Eurographics Symposium on Point-Based Graphics (2004) (2004)
M. Alexa, S. Rusinkiewicz, Xin Guan, Klaus Mueller
In this paper we show how to extend point-based surface rendering to illustrate object motion. We do this by first extruding the circular points into ellipsoids, which fill the space traced out by...
Eurographics Symposium on Point-Based Graphics (2004) (2004)
M. Alexa, S. Rusinkiewicz, Jan Klein
a b c d Visualization of the moving least squares surface (magenta) over a 2D point cloud (black dots) based on different distance functions: (a,c) Euclidean, (b,d) ours based on proximity graphs.
Eurographics Symposium on Point-Based Graphics (2004) (2004)
M. Alexa, S. Rusinkiewicz, Jan Klein
a b c d Visualization of the moving least squares surface (magenta) over a 2D point cloud (black dots) based on different distance functions: (a,c) Euclidean, (b,d) ours based on proximity graphs.
Eurographics Symposium on Point-Based Graphics (2004) (2004)
M. Alexa, S. Rusinkiewicz, Jan Klein
a b c d Visualization of the moving least squares surface (magenta) over a 2D point cloud (black dots) based on different distance functions: (a,c) Euclidean, (b,d) ours based on proximity graphs.
Eurographics Symposium on Point-Based Graphics (2004) (2004)
M. Alexa, S. Rusinkiewicz, Anne Collins, Afra Zomorodian, Gunnar Carlsson, Leonidas Guibas
In this paper, we present a complete computational pipeline for extracting a compact shape descriptor for curve point cloud data. Our shape descriptor, called a barcode, is based on a blend of...
Eurographics Symposium on Point-Based Graphics (2004) (2004)
M. Alexa, S. Rusinkiewicz (editors, Mark Pauly, Niloy J. Mitra, Leonidas J. Guibas
We present a framework for analyzing shape uncertainty and variability in point-sampled geometry. Our representation is mainly targeted towards discrete surface data stemming from 3D acquisition...
Eurographics Symposium on Point-Based Graphics (2004) (2004)
M. Alexa, S. Rusinkiewicz, M. Waschbsch, M. Gross, F. Eberhard, E. Lamboray, ...
We present a framework for progressive compression of point-sampled models. It is based on a multiresolution decomposition of the point set and thus easily allows for progressive decoding. Our method...
Eurographics Symposium on Point-Based Graphics (2004) (2004)
M. Alexa, S. Rusinkiewicz, Enrico Gobbetti, Fabio Marton
We present a simple point-based multiresolution structure for interactive visualization of very large point sampled models on consumer graphics platforms. The structure is based on a hierarchy of...
Eurographics Symposium on Point-Based Graphics (2004) (2004)
M. Alexa, S. Rusinkiewicz (editors, T. Weyrich, M. Pauly, R. Keiser, S. Heinzle, ...
D shape acquisition has become a major tool for creating digital 3D surface data in a variety of application fields. Despite the steady increase in accuracy, most available scanning techniques cause...
Eurographics Symposium on Point-Based Graphics (2004) (2004)
M. Alexa, S. Rusinkiewicz, Diego Nehab, Philip Shilane
Point sampling is an important intermediate step for a variety of computer graphics applications, and specialized sampling strategies have been developed to satisfy the requirements of each problem....
Bounds on k-Neighborhood for Locally Uniformly Sampled Surfaces (2004)
M. Alexa, S. Rusinkiewicz (editors, Mattias Andersson, Joachim Giesen, Mark Pauly, Bettina Speckmann
Given a locally uniform sample set P of a smooth surface S. We derive upper and lower bounds on the number k of nearest neighbors of a sample point p that have to be chosen from P such that this...
On normals and projection operators for surfaces defined by point sets (2004)
Levin's MLS projection operator allows defining a surface from a set of points and represents a versatile procedure to generate points on this surface. Practical problems of MLS surfaces are a...
Efficient and realistic shadow rendering using graphics hardware (2004)
Shadows have a great influence on the looks of a computer generated image. They are not only necessary for an authentic illumination of the scene, they also give cues about the position, size and...
Point based animation of elastic, plastic and melting objects (2004)
Müller, M., Keiser, R., Nealen, A., Groß, M., Alexa, M.
We present a method for modeling and animating a wide spectrum of volumetric objects, with material properties anywhere in the range from stiff elastic to highly plastic. Both the volume and the...
Steerable texture synthesis (2004)
Texture synthesis is typically concerned with the creation of an arbitrarily sized texture from a small sample, where the pattern of the generated texture should be perceived as resembling the...
Context-based surface completion (2004)
Sharf, A., Alexa, M., Cohen-Or, D.
Sampling complex, real-world geometry with range scanning devices almost always yields imperfect surface samplings. These "holes" in the surface are commonly filled with a smooth patch that...
Approximating bounded, non-orientable surfaces from points (2004)
We present an approach to surface approximation from points that allows reconstructing surfaces with boundaries, including globally non-orientable surfaces. The surface is defined implicitly using...
Fast and high quality overlap repair for patch-based texture synthesis (2004)
Patch-based texture synthesis algorithms produce reasonable results for a wide variety of texture classes. They preserve global structure, but often introduce unwanted visual artifacts along patch...
Visual component analysis (2004)
We propose to integrate information visualization techniques with factor analysis. Specifically, a principal direction derived from a principal component analysis (PCA) of the data is displayed...
Laplacian surface editing (2004)
Sorkine, O., Cohen-Or, D., Alexa, M., Rössl, C.
Surface editing operations commonly require geometric details of the surface to be preserved as much as possible. We argue that geometric detail is an intrinsic property of a surface and that,...
Approximating and intersecting surfaces from points (2003)
Point sets become an increasingly popular shape representation. Most shape processing and rendering tasks require the approximation of a continuous surface from the point data. We present a surface...
Hybrid texture synthesis (2003)
Patch-based texture synthesis algorithms produce reasonable results for a wide variety of texture classes. They preserve global structure, but often introduce unwanted visual artifacts along patch...
Differential coordinates for local mesh morphing and deformation (2003)
Mesh vertices are usually represented with absolute coordinates. In some applications, this leads to problems for local operations because of global misalignment. We investigate the idea of...
Vector field visualization using markov random field texture synthesis (2003)
Vector field visualization aims at generating images in order to convey the information existing in the data. We use Markov Random Field (MRF) texture synthesis methods to generate the visualization...
Computing and rendering point set surfaces (2003)
Alexa, M., Behr, J., Cohen-Or, D., Fleishman, S., Levin, D., Silva, C.T.
We advocate the use of point sets to represent shapes. We provide a definition of a smooth manifold surface from a set of points close to the original surface. The definition is based on local maps...
Piecewise circular approximation of spirals and polar polynomials (2003)
Spirals are surprisingly common in science, nature, physics, astronomy, flora and fauna, and the arts. In Cartesian coordinates they are typically transcendental functions, which makes the evaluation...
Direction fields over point-sampled geometry (2003)
Alexa, M., Klug, T., Stoll, C.
We describe techniques to establish local frames over point-sampled manifold surfaces. The tangential alignment of local frames is determined using a wave front algorithm starting from a set of...
Multi-level partition of unity implicits (2003)
Ohtake, Y., Belyaev, A., Alexa, M., Turk, G.
We present a new shape representation, the multi-level partition of unity implicit surface, that allows us to construct surface models from very large sets of points. There are three key ingredients...
Verfahren und Vorrichtung zur Datenanalyse (2003)
Weber, M., Alexa, M., Mueller, W.
DE 10151697 A UPAB: 20030828 NOVELTY - The data analysis process is dependent upon a correlated parameter that is shown on a monitor as a spiral or helical graphical symbol that has a periodicity....
Ray tracing point set surfaces (2003)
Point set surfaces (PSS) are a smooth manifold surface approximation from a set of sample points. The surface definition is based on a projection operation that constructs local polynomial...
Linear geometry interpolation (or morphing) is useful to display key frame animations. This work briefly explains prerequisites and useful properties for morphing and describes a prototype...
An algorithm for striping triangle meshes in the context of OpenSG is presented. The technique is similar to STRIPE, however, a careful yet simple implementation leads to significant faster...
The Duden Ontology: An Integrated Representation of Lexical and Ontological Information (2002)
Alexa, M., Kressig, B., Liepert, M., Reichenberger, K., Rostek, L., Rautmann, K., ...
Linear combinations of transformations (2002)
Geometric transformations are most commonly represented as square matrices in computer graphics. Following simple geometric arguments we derive a natural and geometrically meaningful definition of...
Modellierung einer Gruppe virtueller Charaktere mit verschiedenen Persönlichkeitsmerkmalen (2002)
Bisher beschränkt sich die Interaktion mit virtuellen Charakteren auf die Kommunikation zwischen einem Benutzer und einer Figur. Es gibt jedoch Gründe dafür, anstelle eines einzelnen eine Gruppe...
Refinement operators for triangle meshes (2002)
Refinement operators for triangular meshes as used in subdivision schemes or remeshing are discussed. A numbering scheme is presented, covering all refinement operators that (topologically) map...
Recent advances in mesh morphing (2002)
Meshes have become a widespread and popular representation of models in computer graphics. Morphing techniques aim at transforming a given source shape into a target shape. Morphing techniques have...
Wiener filtering of meshes (2002)
This work investigates smoothing, fairing, or, more generally, filtering of mesh geometry. The approach transfers the ideas of optimal (Wiener) filtering to the setting of meshes. It extends fairing...
Linear geometry interpolation (or morphing) is useful to display key frame animations. This work briefly explains prerequisites and useful properties for morphing and describes a prototype...
An algorithm for striping triangle meshes in the context of OpenSG is presented. The technique is similar to STRIPE, however, a careful yet simple implementation leads to significant faster...
Scan Converting Spirals (2002)
Scan-conversion of Archimedes' spiral (a straight line in polar coordinates) is investigated. It is shown that an exact algorithm requires transcendental functions and, thus, cannot have a fast...
Shape spaces from morphing (2002)
In computer graphics, models of three-dimensional shapes are nowadays mainly represented as meshes. A mesh contains a set of vertices describing geometric positions (and other attributes such as...
W. Mller, U. Spierling, M. Alexa
With the introduction of software agents and assistants, the concept of so-called social user interfaces evolved, incorporating natural language interaction, context awareness and anthropomorphic...
Visualizing Time-Series on Spirals (2001)
Weber, M., Alexa, M., Müller, W.
In this paper, we present a new approach for the visualization of time-series data based on spirals. Different to classical bar charts and line graphs, the spiral is suited to visualize large data...
Spierling, U., Müller, W., Alexa, M., Rieger, T.
With the introduction of software agents and assistants, the concept of so-called social user interfaces evolved, incorporating natural language interaction, context awareness and anthropomorphic...
Shape Spaces from Mesh Morphing (2001)
This work concentrates on the extension of classical mesh morphing (between two shapes) to the linear combination of an aribitrary number of shapes. In this setting, several meshes are bases of a...
We advocate the use of point sets to represent shapes. We provide a definition of a smooth manifold surface from a set of points close to the original surface. The definition is based on local maps...
Mesh Morphing: STAR - State of the Art Report (2001)
Meshes have become a widespread and popular representation of models in computer graphics. Morphing techniques aim at transforming a given source shape into a target shape. Morphing techniques have...
Local Control for Mesh Morphing (2001)
Mesh morphing techniques are capable of producing a sequence of meshes, gradually changing from a source to a target shape. However, current techniques do not allow to describe the local behavior of...
Volume visualization in VRML (2001)
Volume visualization has become an invaluable visualization tool. A wide variety of data sets coming from medical applications (e. g. MRI, CT or 3D ultrasound) or geological sensory information are...
An Animation System for User Interface Agents (2001)
Alexa, M., Hellenschmidt, M., Rieger, T., Berner, U.
With the advent of software agents and assistants, the concept of so called conversational user interfaces evolved, incorporating natural language interaction, dialogue management, and...
A linear space of geometric transformations (2001)
A commutative matrix product is defined by applying transforms associated to the matrices concurrently, not one after the other. In addition, it is shown that powers of matrices are natural scalar...
Alexa, M., Müller, W., Spierling, U., Rieger, T.
With the introduction of software agents and assistants, the concept of so-called social user interfaces evolved, incorporating natural language interaction, context awareness and anthropomorphic...
Design issues for conversational user interfaces: Animating and controlling 3D faces (2000)
Müller, W., Spierling, U., Alexa, M., Iurgel, I.
Software agents and assistants together with their adequate visual representations lead to so-called social user interfaces, incorporating natural language interaction, context awareness and...
Alexa, M., Müller, W., Spierling, U., Rieger, T.
With the introduction of software agents and assistants, the concept of so-called social user interfaces evolved, incorporating natural language interaction, context awareness and anthropomorphic...
Alexa, M., Behr, J., Müller, W.
We discuss potential and limitations of a Morph Node, inspired by the corresponding construct in Java3D. A Morph Node in Java3D interpolates vertex attributes among several homeomorphic geometries....
Merging polyhedral shapes with scattered features (2000)
The paper presents a technique for merging two genus-0 polyhedra. Merging establishes correspondences between vertices of the models as a first step in a 3D morphing process. The technique allows for...
As-Rigid-As-Possible Shape Interpolation (2000)
We present an optic-space morphing technique that blends the interiors of given two- or three-dimensional shapes rather than their boundaries. The morph is rigid in the sense that local volumes are...
Representing Animations by Principal Components (2000)
In this paper, we present a representation for three-dimensional geometric animation sequences. Different from standard key-frame techniques, this approach is based on the determination of principal...
Ein flexibles Präsentationssystem für animierte User-Interface-Agenten und Avatare (2000)
Müller, W., Alexa, M., Rieger, T., Braun, N.
Im Rahmen der Entwicklung und Gestaltung von Systemen, die eine natürlichere Mensch-Maschine-Interaktion als bisher weitverbreitete Schnittstellen auf Basis des Paradigma des Direct Manipulation...
Metamorphosis techniques for images and volume models have gained widespread use and reached a mature state offering a variety of user-friendly features including the specification of feature...
Merging Polyhedral Shapes with Scattered Features (1999)
The paper presents a technique for merging two genus 0 polyhedra. Merging establishes correspondences between vertices of the models as a first step in a 3D morphing process. The technique allows for...
Visualization by Examples: Mapping Data to Visual Representations using Few Correspondences (1999)
In this paper we propose a new approach for the generation of visual scales for the visualization of scalar and multivariate data. Based on the specification of only a few correspondences between the...
Morphing is a well known technique to generate smooth transitions between two objects. We propose a more general understanding of morphing: First, we use morphing to describe objects as a composite...
Morphing is a well known technique to generate smooth transitions between two objects. We propose a more general understanding of morphing: First, we use morphing to describe objects as a composite...
Visualization by Metamorphosis (1998)
This paper proposes the use of metamorphosis-techniques to visualize parametric data. Metamorphosis-techniques provide a way to generate smooth transitions of one object into another, a process...