abstracts_siggrad

Real-Time Simulations for Animation and Control of Physical Phenomena

Jos Stam

In this talk I will present some of my research done at Alias Systems in real-time simulations of physical phenomena. In particular I will describe a stable solution of fluid flow. But real-time cloth, hair, caustics and diffraction effects will also be covered. I will then show how these fast simulations can be used to control physical systems to achieve particular effects. For example, I will describe my recent work with Treuille et al from the University of Washington in controlling smoke animations using key frames.

The making of Battlefield 1942

Johan Persson

Come and listen to the story of how Battlefield 1942 was made. Starting with the first steps of coming up with a game-concept and persuading a publisher to sign a deal. Moving on to the huge efforts, complex process and the hurdles that needed to be overcome in production, and ending with the final stages of Alpha and Beta-testing.

Frictional contact problems for rigid multibody systems: a review of models methods.

Claude Lacoursière

Several models and methods for solving frictional contact problems in rigid multibody systems for interactive use are presented within a comparative framework. Analyzes of physical anomalies arising from model approximations are presented and the performance of the solvers is investigated using both random problems as well as actual simulation data from the Vortex toolkits. The performance analysis demonstrates that none of the existing solvers provide a good combination of accuracy, robustness,
and scalability; cases can be found which make any solver behave poorly. New directions for fast, robust and scalable solver development are presented. The review concludes by demonstrating how the methods for frictional contact problems can be used in other applications such as cloth simulation and multi-domain physics simulations.

Perceptual features for computer graphics and visualization

Lars Kjelldahl

Perception has a relation to computer graphics and visualization. The background for this is mainly that the image handling used in graphics and visualization should use the limitations and properties of the human visual system. This includes both features that can't be rendered on a screen such as a complete scale of intensities (generating the tone mapping problem) and features that do not need to be rendered such as some fine details. In this presentation we will give an overview of the area and present some of the perceptual consideration useful for graphics and visualization.

The CGEMS server for educational material

Lars Kjelldahl

At the computer graphics workshop held in july 2002 in Bristol organized jointly by SIGGRAPH and Eurographics the needs for a server for computer graphics educational material were identified. Those needs, which include kind of material wanted, reviewing policy, technical aspects, etcetera has been revised in discussions through email, at SIGGRAPH2003 and Eurographics2003. A server has been implemented. The first contributions to the server have recently been submitted. The aim of the presentation at SIGRAD2003 would be to spread knowledge of the server and the possibilities it offers. Lars Kjelldahl participated in the Bristol workshop and has also given comments later, but the main work was done by Figueiredo, Eber and
Jorge.

Interactive Simulation of Granular Matter

Kenneth Holmlund, Andreas Lind, Rami Morssy

We present a method for interactive simulation of granular matter e.g. sand, gravel and soil, and also examples from a sample implementation in a vehicle simulator system. Our model is based on a particle system with an attractive short-range pair potential, hard core repulsion and inelastic collisions. We use heuristic arguments to show how this model can produce plausible simulations for the dynamics of granular material at an intrinsic mesoscopic length scale. This model system has also been integrated with a rigid-body simulation system. We also present an overview of the physics of granular material in general, and a analysis of the necessary requirements model systems for interactive and computer graphics intense applications. We look at different norms for plausibility based on spatial and temporal considerations, and we also analyze the real-time aspects and scalability issues of the problem.

Examination of the possibility to use OpenSceneGraph for real-time graphics in a CAVE-environment

Odd Tullberg, Linus Valtersson

This paper describes the examination of whether OpenSceneGraph (OSG) can be used to render real-time graphics in a CAVE-environment. It starts by describing the systems used for graphics today and motivates why it is desirable to use OSG instead. After this, the examination itself is described. The result from this examination is that OSG can be used to render real-time graphics in a CAVE-environment, but the task is not trivial. OSG alone is not enough to render graphics satisfactory, it requires an extra layer dealing with all VR-features included in the environment. To solve this, VR Juggler (VRJ) was used on top of OSG. VRJ is not the only option to use together with OSG, but it was the one that proved to work most satisfactory. The combination of OSG and VRJ was used to implement an application displayed at Vetenskapsfestivalen 2003.

Surface intersection for co-located 3D scalar fields

Patric Ljung, Anders Ynnerman

This paper presents new methods for efficient extraction of intersection lines between iso-surfaces of any pair of co-located 3D scalar fields. We have based our first method on the Marching Cubes algorithm which has been augmented to produce an additional data structure that makes it possible to reduce the complexity of the general surface intersection extraction from O(N^2) to O(sqrt(N)) where N denotes the number of triangles in the arbitrary surfaces. The second method directly extracts the intersection lines based on finding intersection points on the faces of the voxels for two implicit surfaces sampled on aregular grid. We use a simple classification scheme to early terminate further testing of voxels that don't have both surfaces intersecting it. We also present efficient methods for fast curve generation through combination of line segments generated by our intersection algorithm. We use an indexing structure to accelerate access and matching of intersection line segments to be combined into closed for open curves. The presented methods have been used to identify and visualize nodal lines in 3D quantum and wave chaos data. These data are represented by a volume of complex values and a nodal line is a connected curve where the complex iso-value Ziso= 0+i0. This type of chaos is believed to represent physical phenomena present in for example quantum mechanics, microwaves, fiber optics, and acoustics.