1,695 Works

Frame-Coherent Stippling

Oscar E. Meruvia Pastor & Thomas Strothotte
Eurographics 2002 - Short Presentations

A Short Survey on Optical Material Recognition

M. Weinmann & R. Klein
The complexity of visual material appearance as observed in the huge variation in material appearance under different viewing and illumination conditions makes material recognition a highly challenging task. In the scope of this paper, we discuss the facts that make material appearance that complex and provide a survey on technical achievements towards a reliable material recognition that have been presented in the literature so far. In addition, we discuss still open challenges that might be...

Solid-Interpolating Deformations: Construction and animation of PIPs

Anil Kaul & Jarek Rossignac
Computer programs that simulate the deformations of geometric shapes have played a key role in the increasing popularity of software tools for artistic animation. Previously published techniques for specifying and animating deformations are either limited in their domain or ill suited for interactive editing and visualization. This is because the effects of alterations performed by the animator on the model's parameters may not always be anticipated, and because realtime animation may only be produced by...

Mathematical Models for Semi-globalized Spectral Synthesis

Ken-Ichi Anjyo
Semi-globalized spectral synthesis is proposed as a new tool for three-dimensional scene description consisting of many natural objects, such as terrain, sea waves, and clouds. The method is based on the mathematical theory of spectral representation of stochastic processes. In this paper, mathematical models in the method are presented under rigorous formulation and then their stochastic properties are shown. Some simple techniques for practical improvements of the original models in depicting scenes are also explained...

Shading and Shadowing with Linear Light Sources

Pierre Poulin & John Amanatides
In virtually all rendering systems, linear light sources are modeled with a series of point light sources that require considerable computing resources to produce realistic looking results. A general solution for shading surfaces illuminated by a linear light source is proposed. A formulation allowing for faster computation of the diffuse component of light reflection is derived. By assuming Phong's specular component, simple, inexpensive and convincing results are produced with the use of a Chebyshev approximation....

MOVE-X: A System for Combining Video Films and Computer Animation

Gerhard Ertl, Heimo Müller-Seelich & Behnam Tabatabai
The objective of the presented project was to implement a system for the visualization of buildings. The system is used to create movies of buildings and interior rooms before they are built. For a realistic impression of a building it is very important to show its actual environment in the film. The designed software solution permits to create films where real images of the environment are overlaid with computer generated images of the building. In...

A Symmetrical Input/Output Model

Niels Vejrup Carlsen & Niels Jorgen Christensen
When choosing a graphics system for the run-time support component of a User Interface Management System (UIMS) several problems arise. Existing inputloutput models employed by graphics systems lack support for fine grain design control and for defining links between input and output. Furthermore, hardware maintainability is a problem. We have introduced a new inputloutput model, the symmetrical translation model (STM), which solves these problems through extensibility and symmetry. All input and output techniques are implemented...

Geometric Modelling from Range Image Data

Francis Schmitt, Xin Cken & Wen-Hui Du
An adaptive surface fitting algorithm is proposed for modelling the digitized surface of a real object described by an array of 3D points sampled on a rectangular mesh and stored in the form of a range image. A G1 -piecewise approximation of the data is obtained by using an adaptive top-down method which combines the Delaunay triangulation technique with a triangular Gregory-Bezier patch model (tGB). The method begins with a rough approximation of the surface...

Using temporal and spatial coherence for accelerating the calculation of animation sequences

Eduard Gröller & Werner Purgathofer
Ray tracing is a well known technique for generating realistic images. One of the major drawbacks of this approach are the extensive computational requirements for image calculation. When generating animation sequences frame by frame the computational cost might easily become intolerable. In the last years several methods have been devised for accelerating the computational speed by using spatial and temporal coherence. While these techniques work only under certain restrictions, a new approach is presented in...

THREE-DIMENSIONAL TEXTURING USING LATTICES

Robert R. Lewis
This paper describes a way to perform realistic three-dimensional texturing of ray-traced objects with irregular surfaces. Such texturing has teen done in the past with texture mapping, particle systems, or volumetric methods. We propose an alternative to these called a lattice. Lattices work as fast but inexact ray tracers. As long as lattices are used for small objects, though, the inexactness doesn't show on the scale of the display, and the result is acceptable. The...

AN APPROACH TO THE FORMAL SPECIFICATION OF THE COMPONENTS OF AN INTERACTION

Giorgio P. Faconti & Fabio Paterno
In this paper we present the preliminary results from a work aiming to the formal specification af a model suitable for the description of interactive graphics program within the framework defined by the Reference Model for Computer Graphics Systems, actually under development within the International Organization for Standardization. The architecture defined by the Computer Graphics Reference Model, at its actual state of development, is shortly presented with particular attention paid to the concepts used in...

WSE: An Environment for Exploring Window Strategies

Marja-Riitta Koivunen
This paper describes Window Strategies Environment (WSE), which is an environment for exploring different window strategies. It is a tool for developers who want to implement and explore different window strategies easily. WSE uses object oriented methodology offering four hierarchical levels for customizing predefined window strategies. The highest level is a simple modifiable language for describing a few essential commands for each strategy. This kind of tool helps the developers to implement and test several...

Simultaneous Stereo Rectification and Distortion Correction with Application to DoF Synthesis

Chen Ting Yeh, Tien-Yu Ho, Szu-Hao Huang & Shang-Hong Lai
Stereo rectification based on epipolar geometry is an image transformation process which is used to align the rectified stereo images to be coplanar. For image pairs captured by low-cost stereo camera systems, image noises and optical distortions in images may lead to errors in depth estimation. In this paper, a novel algorithm is proposed to simultaneously solve the stereo rectification and distortion correction problems in an integrated optimization framework. The estimated disparity maps are then...

Light-Guided Tree Modeling of Diverse Biomorphs

Lei Yi, Hongjun Li, Jianwei Guo, Oliver Deussen & Xiaopeng Zhang
Creation of tree models faithful to light environment is an important task in computer graphics as well as in botanical research, such as horticulture and forestry. In this paper, we propose an approach to model virtual trees with constraints of light resources and tree morphological properties. By the allocation of received light resources, tree model parameters are estimated, including branching directions and branching sizes. The light energy is calculated by sampling the environmental space, so...

Pairwise Surface Registration Using Local Voxelizer

Peng Song & Xiaoping Chen
Surface registration is the process that brings scans into a common coordinate system by aligning their overlapping components, which can be achieved by finding a few pairs of matched points on each scan pair using shape descriptors and employing the matches to compute an alignment transformation. This paper proposes a local voxelizer descriptor, and the key idea is to define a unique local reference frame (LRF) using the local shape around a basis point, perform...

A Convex Clustering-based Regularizer for Image Segmentation

Benjamin Hell & Marcus Magnor
In this paper we present a novel way of combining the process of k-means clustering with image segmentation by introducing a convex regularizer for segmentation-based optimization problems. Instead of separating the clustering process from the core image segmentation algorithm, this regularizer allows the direct incorporation of clustering information in many segmentation algorithms. Besides introducing the model of the regularizer, we present a numerical algorithm to efficiently solve the occurring optimization problem while maintaining complete compatibility...

A Taxonomy of Integration Techniques for Spatial and Non-Spatial Visualizations

Johannes Sorger, Thomas Ortner, Harald Piringer, Gerd Hesina & Eduard Gröller
Research on visual data representations is traditionally classified into methods assuming an inherent mapping from data values to spatial coordinates (scientific visualization and real-time rendering) and methods for abstract data lacking explicit spatial references (information visualization). In practice, however, many applications need to analyze data comprising abstract and spatial information, thereby spanning both visualization domains. Traditional classification schemes do not support a formal description of these integrated systems. The contribution of this paper is a...

Vector-to-Closest-Point Octree for Surface Ray-Casting

Ismail Demir & Rüdiger Westermann
GPU voxel-based surface ray-casting has positioned as an interesting alternative to rasterization-based rendering approaches, because it allows using many processing units simultaneously, can effectively exploit thread level parallelism, and enables fine-granularity occlusion culling on the pixel level. Yet voxel-based techniques face the problem that an extremely high resolution is necessary to avoid block artifacts at high zoom levels. In this work, we propose a novel improvement of voxel-based ray-casting to overcome this limitation. By using...

COLOUR SECTION

COLOUR SECTION

Dynamic Management of 3D Scenes

Gerard Hegron
When simulating a moving observer or sensor in a 3D scene which contains a large number of objects, only the objects lying in the field of view or of interaction, named the local data base, have to be taken into account in order to decrease, at each step, computation time necessary for either image generation or various processings. This paper presents an algorithm which achieves the dynamic management of the local data base, that is...

HIRASP: A Hierarchical Interactive Rastergraphics System Based on Pattern Graphs and Pattern Expressions

Wim J.M. Teunissen & Jan Van Den Bos
To exploit the full capabilities of raster graphics, two and three dimensional drawing primitives should play a preponderant role in the specification of a graphics standard. In addition there should be facilities for modeling and hierarchy. HIRASP presents an integrated language system fulfilling these requirements. The pattern is used as the basic drawing primitive. It consists of a colour function defined over an arbitrary OD to 3D domain. There are a number of basic pattern...

An Automatic Interpolation Method of Grayvalued Images Utilizing Density Contour Lines

Takeshi Agui, Minoru Saito, Masayuki Nakajima & Yukihiro Arai
This paper presents an automatic method of interpolation or inbetweening for gray valued images, which have been difficult to be processed automatically. The method consists of three parts. The first i s the extraction of density contour lines from a pair of gray valued key frame images, the second i s the interpolation of the contour lines and the l a s t is the generation of in-between gray valued images. In the second part,...

Grafields: Field-Directed Dynamic Splines for Interactive Motion Control

Xavier Pintado & Eugene Fiume
This paper presents an interactive system for motion control that emphasizes object interaction. The fundamental mechanism provided to support interaction between objects is the field. We present a new technique called dynamic splines which dynamically generates a trajectory under field control. Dynamic splines mimic the kinematic behaviour of a particle moving in a field, yet, it is computationally inexpensive compared to full physical dynamic approaches. We also show how to extend the field approach to...

Construction and Animation of a Synthetic Actress

N. Magnenat-Thalmann & D. Thalmann
This paper describes a method for creating and animating a synthetic actress. It emphasizes the methodology used to generate realistic images and motions. In particular, points which are often ignored in the literature are explained in detail: for example, the planning and preparation of models for digitizing, composition, skeleton installation and the animation process itself.

Conic Beta-Splines with Local Tension Control for Interactive Curve Fitting

Binh Pham
Polynomial Beta-splines were introduced by Barsky as an extension of polynomial B-splines with bias and tension parameters which allow more flexibility in controlling shape in curve fitting. It is possible to show that a quadratic Beta-spline segment is equivalent to a quadratic B-spline segment with suitably modified control vertices. This provides a simple method for evaluating quadratic Beta-splines using De Boor's algorithm for calculating polynomial B-splines. A representation for conic Beta-splines with one tension parameter...

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