Spyros Vosinakis

Hermes – a framework for location-based data management

The aim of this paper is to demonstrate Hermes, a robust framework capable of aiding a spatio-temporal database developer in modeling, constructing and querying a database with dynamic objects that change location, shape and size, either discretely or continuously in time. Hermes provides spatio-temporal functionality to state-of-the-art Object-Relational DBMS (ORDBMS). The prototype has been designed as an extension of STAU [6], which provides data management infrastructure for historical moving objects, so as to additionally support the demands of real time dynamic applications (e.g. Location-Based Services – LBS). The produced type system is packaged and provided as a data cartridge using the extensibility interface of Oracle10g. The offspring of the above framework extends PL/SQL with spatio-temporal semantics. The serviceableness of the resulting query language is demonstrated by realizing queries that have been proposed in [9] as a benchmarking framework for the evaluation of LBS.

SimHuman: A Platform for Real-Time Virtual Agents with Planning Capabilities

In this paper, we present SimHuman, a platform for the generation of real-time 3D environments with virtual agents. SimHuman is highly dynamic and configurable, as it is not based on fixed scenes and models, and has an embedded physically based modelling engine. Its agents can use features such as path finding, inverse kinematics and planning to achieve their goals. The paper explains in detail design and implementation issues and presents the architecture of the system as well as an illustrative example.

A Tool for Constructing 3D Environments with Virtual Agents

The use of Virtual Environments as a user interface is essential for certain types of applications, both in education and entertainment. These worlds are even more attractive for the user when they are neither static nor pre-scripted, but have dynamic characteristics and are populated by autonomous entities, also called virtual agents. There has been a lot of research concerning visualization, animation and behavior of virtual agents, but there are no generic architectures, methodologies and tools for the development of intelligent virtual environments, i.e. 3D environments with autonomous virtual agents. In this paper, we present SimHuman, a tool for the construction of virtual worlds with autonomous entities, targeted for a specific group of applications, such as simple simulation systems, virtual environments, educational applications, multimedia presentations, etc. It consists of a programming library and two utilities and it is highly dynamic and configurable, as it is not based on fixed scenes and models. It has embedded characteristics such as Inverse Kinematics, Physically Based Modeling, Collision Detection and Response, and Vision. SimHuman incorporates some important features for designing and building virtual environments and turns out to be an effective tool for interactive 3D applications with virtual agents.

An Intelligent Agent Framework in VRML Worlds

Agent-based technologies have been rapidly emerging since the beginning of the 1990s [1–5]. J.P. Muller, [4], states that ‘Agents are autonomous or semi-autonomous hardware or software systems that perform tasks in complex, dynamically changing environments’. This means that Intelligent Agents observe the environment, maintain an internal representation of the world, make decisions and perform tasks (executing actions).

Programmable Agent Perception in Intelligent Virtual Environments

In this paper, we propose a perception model for virtual agents based on a two-layered architecture. Each agent is equipped with a sensing mechanism that retrieves the objects in its field of view and stores them in its memory, and with a perception module that applies a set of rules on them and generates its beliefs. We propose a scripting language for defining such perception rules using condition->assertion statements, and describe in detail an example of a perception case.

Synthetic Characters with Emotional States

A new trend that has emerged in the field of applied artificial intelligence in the past few years is the incorporation of emotion emulation mechanisms in situated agent systems. Several researchers in the field of psychology and neural science agree that emotion is an essential aspect of human intelligence, diverging from the traditional treatment of emotion as something that inhibits rational thinking. This argument has also influenced the area of artificial intelligence and especially the young, yet vibrant field of Intelligent Virtual Agents, where it has become accepted that emotion is a key issue to achieve believable agent behaviour. The increased interest for emotions has resulted in several computational emotional models having been presented, with diverse approaches, generically classified into cognitive and non-cognitive, inspired by areas such as neural science. Hybrid approaches have also appeared, combining both cognitive and non-cognitive elements in an attempt to accurately describe the inner workings of emotional mechanisms. Such a hybrid model is the one we adopt in this paper, aiming to apply it to SimHuman, an intelligent virtual agent platform, in order to introduce emotion awareness and affective behaviour to the agent architecture.

Visualising logic programs in virtual worlds

In this paper we present an architecture and a methodology for visualising the output of Logic Programs and integrating different technologies such as Logic Programming, Object — Oriented Programming and Virtual Reality. We are currently working on developing a generic tool for 3D visualisation of Logic Programs.