SIGGRAPH 2004 - The 31st international conference on computer graphics and interactive techniques
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The Invisible Train: A Handheld Collaborative Augmented-Reality Demonstrator
The Invisible Train is a multi-player game that illustrates the capabilities of a framework for rapidly developing self-contained, distributed graphics applications on a variety of commercially available handheld computers.

Life Enhancement
As handheld devices become more widespread, the need for software tools to develop a new range of mobile applications is likely to increase. This software framework forms a sound basis for development of a variety of mobile software applications, ranging from handheld location-based information systems to miniaturized versions of "classic" mobile augmented-reality applications.

Hardware-accelerated mobile graphics solutions are generating a need for a software infrastructure that permits development of applications that go beyond simple games and multimedia gimmicks. The Invisible Train development team focuses mainly on systems/framework design, so we will be able to utilize upcoming hardware-accelerated mobile graphics systems (from which we expect tremendous quality and performance improvements) in order to engineer more involving mobile applications.

The goal of this project is to strike an optimal balance between mobility and performance criteria, so it focuses on personal digital assistants as hardware platforms. This PDA-based approach is unique because it builds upon the PDA as a central system component that is unconstrained in terms of infrastructure requirements instead of just using it as a thin client or a mere server-controlled input/output device.

The Invisible Train installation illustrates how augmented-reality applications can be built with a high-level mobile AR framework. The framework's core components are:

Graphics subsystem
This mobile AR framework uses KLIMT, a software renderer that implements a subset of the OpenGL and OpenGL|ES API. Klimt is being developed with portability and performance in mind and is available under the GPL for Linux, Windows, and WindowsCE. We also ported the well known Coin library (an OpenInventor reimplementation by Systems In Motion) to the handheld platform to allow for rapid data-driven application development with scene-graphs.

Tracking subsystem
The framework includes an integrated fiducial-based visual-pose tracking system. We further enhanced tracking accuracy with a multi-marker relaxation algorithm. The use of vision-based tracking is a natural choice because of the increasing availability of cameras for and in mobile devices.

Communications subsystem
To handle synchronization tasks mandated by distributed systems, the communications layer is based on ACE (the Adaptive Communications Environment being developed at Washington University).

Sunday, 8 August
1:45 - 3:30 pm
Room 404AB

Thomas Pintaric
Vienna University of Technology

Dieter Schmalstieg
Daniel Wagner
Vienna University of Technology

emerging technologies jury and committee
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Conference 8-12 August, Exhibition 10-12 August.  In Los Angeles, CA