Christian Geiger

Rapid development of expressive AR applications

We describe our approach of developing AR applications with expressive visual representations and realistic object behavior. We combine concepts from high-level scene graphs, physical simulation libraries and a Java binding for ARToolkit with the ideas of iterative prototyping and show that rapid development of expressive AR applications using Java is possible.

Visual-textual prototyping of 4D scenes

3D-graphics are becoming popular in a steadily increasing number of areas such as entertainment, scientific visualization, simulation, and virtual reality. Despite this rapid growth the generation of animated 3D scenes is by no means trivial. Since animated 3D objects evolve over time the authors denote these objects as 4D. The article presents a novel approach to the rapid prototyping of 4D models. They introduce the AAL (Animated Agent Layer) system. AAL is an interpreter-based approach covering a textual (AAL-PR) as well as a visual command language (AAL-VL) for the specification of the dynamics in 4D scenes. AAL provides support for different levels of abstraction: primitives, structured objects, animated objects, and animated (autonomous) agents.

Visual modeling and 3D-representation with a complete visual programming language-a case study in manufacturing

The main goal of the article is to evaluate the suitability of visual programming languages, i.e., Pictorial Janus (K. Kahn and V. Saraswat, 1990), for the modeling of complex systems and their control strategies. These systems can be seen as networks of communicating objects. Objects select strategies for suitable actions based on incoming messages. Our field of investigation is in computer integrated manufacturing considering the example of a car manufacturing cell. This color sorting assembly buffer (CSAB) schedules jobs in queues. The jobs represent car bodies scheduled in feeder lines for the enameling. Feeder lines collect raw bodies to blocks. Blocks are bodies which are to be enameled by the same color. This organization decreases the cost of expensive change-over-times when changing colors at the enamelling. Blocks of bodies are dislocated from the queue and enameled successively. Contradictory system goals, such as minimizing color changes and preserving the sequence of incoming jobs, have to be regarded by appropriate control strategies. Due to the complexity of this (NP complete) problem and to real time requirements for online control there are no optimal strategies on hand. Consequently, suitable heuristics have to be developed. Often they are designed applying a trial-and-error method. A modeling framework has to support the rapid prototyping of these systems as well as an expressive end user oriented representation. Both are essential requirements since end users need other visualization techniques than experienced designers due to their different knowledge and interests.

The AR-ENIGMA: a PDA based interactive illustration

The AR-ENIGMA combines a PDA (personal digital assistant) with a camera, a high-speed wireless network connection and AR (augmented reality) technology to enable museum visitors to interact with an Enigma encryption machine.

Testable design representations for mobile augmented reality authoring

This paper applies the idea of a continuously testable design representation to authoring of augmented realities for mobile devices.

A visual programming language for qualitative data

Modeling of human knowledge and reasoning requires the formulation of uncertainty in its various forms. Fuzzy logic was introduced to directly support these applications (H. Zimmermann, 1991). Fuzzy control (FC) which is based on fuzzy logic allows one to control complex systems based on qualitative information like human knowledge (C. Geiger and G. Lehrenfeld, 1994). In fuzzy logic, fuzzy sets are usually defined and manipulated by means of complex mathematics, whereas the fuzzy control process is frequently outlined by visual sketches based on set diagrams in order to enhance the comprehension of the inference process. The rule based execution of this process usually follows the lines of rule based visual programming languages (VPLs), i.e., languages comparable to Agentsheets and ChemTrains. This strongly indicates that VPLs are thus well applicable for this use. We first outline the basic concepts of fuzzy logic and fuzzy control. Thereafter, we sketch a visual language which integrates fuzzy set diagrams in the visual representation of rules. The basic concepts are inherited from the complete visual programming language, Pictorial Janus (PJ). However, we significantly simplify PJs visual concepts in order to adapt it for our purpose.

Modellierung intelligenter Strategien in komplexen Systemen mit Concurrent Fuzzy Prolog

Um die Entwicklung von Fuzzy Systemen und Fuzzy Strategien effizienter zu gestalten, ist es notwendig dem Entwickler Werkzeuge in die Hand zu geben, welche ihn schon in der Modellierungsphase effektiv unterstutzen. Als ein solches Modellierungswerkzeug bietet sich ConFuP (Concurrent Fuzzy Prolog) [8, 7] an. ConFuP basiert auf der parallelen logischen Programmiersprache CP (Concurrent Prolog), erweitert mit Konzepten zur Darstellung von Unsicherheit und qualitativem Wissen.