Showing papers by "Ana Paiva published in 2007"

FearNot!: an emergent narrative approach to virtual dramas for anti-bullying education

Abstract: FearNot! is a story-telling application originally created in the EU FP5 project VICTEC and now extended in the FP6 project eCIRCUS [eCIRCUS 07]. It has applied ideas from Forum Theatre [Boal 79] to the domain of education against bullying. In Forum Theatre, sections of an audience take responsibility for a specific character in the unfolding drama, played by an actor who always stays in role. Episodes in which the actors improvise within an overall narrative framework are broken by interaction sections in which the audience sections talk over with 'their' character what they should do in the next dramatic segment. The actor is free to reject advice that seems incompatible with their role, and may also suspend a dramatic episode if it seems necessary to get further advice.

Expression of Emotions in Virtual Humans Using Lights, Shadows, Composition and Filters

Abstract: Artists use words, lines, shapes, color, sound and their bodies to express emotions. Virtual humans use postures, gestures, face and voice to express emotions. Why are they limiting themselves to the body? The digital medium affords the expression of emotions using lights, camera, sound and the pixels in the screen itself. Thus, leveraging on accumulated knowledge from the arts, this work proposes a model for the expression of emotions in virtual humans which goes beyond embodiment and explores lights, shadows, composition and filters to convey emotions. First, the model integrates the OCC emotion model for emotion synthesis. Second, the model defines a pixel-based lighting model which supports extensive expressive control of lights and shadows. Third, the model explores the visual arts techniques of composition in layers and filtering to manipulate the virtual human pixels themselves. Finally, the model introduces a markup language to define mappings between emotional states and multimodal expression.

I Know What I Did Last Summer: Autobiographic Memory in Synthetic Characters

Abstract: According to traditional animators, the art of building believable characters resides in the ability to successfully portray a character's behaviour as the result of its internal emotions, intentions and thoughts. Following this direction, we want our agents to be able to explicitly talk about their internal thoughts and report their personal past experiences. In order to achieve it, we look at a specific type of episodic long term memory. This paper describes the integration of Autobiographic Memory into FAtiMA, an emotional agent architecture that generates emotions from a subjective appraisal of events.

An authoring tool for an emergent narrative storytelling system

Abstract: In this paper we present the initial conceptual design of an authoring tool for the emergent narrative agent architecture FAtiMA that powers the virtual bullying drama FearNot!. We explain that the process of authoring emergent narrative to a large part consists of designing a planning domain for a virtual character planner and explain the difficulties this task poses to the non-technical author. After reviewing existing authoring tools and evaluating them in terms of their applicability to FAtiMA, we introduce a novel concept of approaching the authoring task, in which the author is playing through example story lines that are used to gradually increase the knowledge and intelligence of a virtual character. This concept is extended by a mixed initiative feature, which allows the author to cooperate with the character planners while providing the example stories. Finally we concretize our idea and explain our intended implementation of it within the FearNot! Framework. We believe that our design, although being specified with a particular architecture (FAtiMA) in mind, may provide some interesting ideas to others, who are trying to solve the authoring problem for interactive storytelling sys-

What can i do with this?: finding possible interactions between characters and objects

Abstract: Virtual environments are often populated by autonomous synthetic agents capable of acting and interacting with other agents as well as with humans. These virtual worlds also include objects that may have different uses and types of interactions. As such, these agents need to identify possible interactions with the objects in the environment and measure the consequences of these interactions. This is particularly difficult when the agents never interacted with some of the objects beforehand. This paper describes SOTAI - Smart ObjecT-Agent Interaction, a framework that will help agents to identify possible interactions with unknown objects based on their past experiences. In SOTAI, agents can learn world regularities, like object attributes and frequent relations between attributes. They gather qualitative symbolic descriptions from their sensorial data when interacting with objects and perform inductive reasoning to acquire concepts about them. We implemented an initial case study and the results show that our agents are able to acquire valid conceptual knowledge.

Agents that remember can tell stories: integrating autobiographic memory into emotional agents

Abstract: For the past few years many new applications are being developed featuring interactive environments populated with autonomous virtual agents capable of acting according to their goals, beliefs and even social relations. Such agents must be able to interact with each other, and more importantly with the user, thus involving the users in an engaging narrative experience. To achieve these, in this paper we describe the essential event structure in an autobiographic memory, event reconstructions in memory retrieval process and the influences of such past events in interpersonal relations.

FearNot! demo: a virtual environment with synthetic characters to help bullying

Abstract: This demo features FearNot!, a school-based Virtual Learning Environment (VLE) populated by synthetic characters representing the various actors in a bullying scenario. FearNot! uses emergent narrative to create improvised dramas with those characters. The goal is to enable children to explore bullying issues, and coping strategies, interacting with characters to which they become affectively engaged. Through their appearance, behaviours and affect, these characters are able to trigger empathic relations with the user. FearNot! is used for Personal and Health Social Education (PHSE) for children aged 8--12, in the UK, Portugal and Germany.

Authoring emergent narrative-based games

Abstract: In this article, we address the particular issue of authoring interactive narrative with respect to video-games and interactive storytelling . We first introduce the narrative paradox between interactivity and narrative content in virtual environments and consider its impact on game design and development. We then introduce the concept of the Emergent Narrative (EN) and the particular phil osophy it has been developed upon. Finally, we describe an authoring process for this approach that reflects on the characteristics of interacting within such a narrat ive framework.

Are We Telling the Same Story? Balancing Real and Virtual Actors in a Collaborative Story Creation System.

Abstract: Interactive Drama applications aim at offering interactive experiences to the participants by empowering them with active participation and engagement in the development and solution of a story. However, introducing this interactivity leads to a natural conflict between the participant’s freedom of interaction and the system’s control, or, more precisely, the author’s expectations in the development of the story. As such, favouring one over the other, leads to different experiences and perhaps even different genres. This balance has been extensively discussed amongst researchers in the community, and yet achieving such balance is still regarded not only as a challenge but also as an art itself. In this paper we discuss a system, I-Shadows that is an Interactive Drama based on Autonomous Affective Characters and Drama theory. In this system we tried to reach such balance through considering the storytelling experience as the “collaboration” that emerges from the real actors (the users) and the virtual actors (some Chinese shadow puppets). Supported by improvisation theory, our actors (shadows) act as if they are collaborating with the user in achieving the story. However, to achieve that, the virtual actors need to have an agent architecture that supports emotion reactions, goal oriented behaviour and social interactions. Aspects such as role taking, waiting for the right time to say their line, have a coherent personality, turn taking, and others, are considered in the minds of the virtual actors, allowing for this balance to be reached. Furthermore, and to complement this aspect of autonomy of the agents, the coordination problem between the actors is also helped by the presence of a specific agent (a story director) that allows for agents to appear or disappear from the scene of the story. This approach was used in the construction of I-shadows, which, although not yet evaluated, has revealed its power.

The user in the group: evaluating the effects of autonomous group dynamics

Abstract: Autonomous characters in virtual environmentshave the potential to improve the interaction experience of users, specially, their social experience.This effect is driven by the interactions occurring between users and the autonomous characters, that in certain scenarios can be in the context of a group.However, for these group interactions to be successful, it is not enough to assure that the autonomous charactersbehave in a coherent manner from an individual perspective,but it is also necessary that they exhibit behavioursthat are coherent with the group composition, context andstructure. Therefore, we have developed a model to support believable group dynamics of autonomous characters, inspired in theories developed in human social psychological sciences. This model defines the knowledge that eachindividual should build about the others and about the group it belongs, and how this knowledge drives their interactions in the group. The model was integrated in the mind of the autonomous characters that perform a collaborative task, in a computer game, with a human player. The game was used in a study that showed that players' interaction experience was better when interaction with groups that followed our model, namely, regarding trust and social identification with the group. In addition, we found some evidence that players prefer playing in groups that have higher level of conflict.

eCIRCUS: building voices for autonomous speaking agents.

Abstract: This paper describes our work integrating automatic speech generation into a virtual environment where autonomous agents are enabled to interact by natural spoken language. The application intents to address bullying problems for children aged 9-12 in the UK and Germany by presenting improvised dramas and by asking the user to act as an “invisible friend” of the victimised character. As we are addressing an elementary school environment one specification of the resulting voice was building agecorresponding young school kids voices. The second specification addresses building a low-resource speech generation system which is capable to run on older school computers but is still fast enough in response time to guaranty a fluent conversation between the agents. Third requirement was integrating the speech-module with the agents. We focus on the speech generation system itself, pointing out possible implementation issues in building non-controlled speech interaction in virtual environments Furthermore we describe the problems arising in building unit-selection based child’s' voice TTS and shows alternative methods to child’s voice recording by deploying voice transformation methods.

Telling stories with a synthetic character: understanding inter-modalities relations

Abstract: Can we create a virtual storyteller that is expressive enough to convey in a natural way a story to an audience? What are the most important features for creating such character? This paper presents a study where the influence of different modalities in the perception of a story told by both a synthetic storyteller and a real one are analyzed. In order to evaluate it, three modes of communication were taken into account: voice, facial expression and gestures. One hundred and eight students from computer science watched a video where a storyteller narrated the traditional Portuguese story entitled "O Coelhinho Branco" (The little white rabbit). The students were divided into four groups. Each of these groups saw one video where the storyteller was portrayed either by a synthetic character or a human. The storyteller's voice, no matter the nature of the character, could also be real or synthetic. After the video display, the participants filled a questionnaire where they rated the storyteller's performance. Although the synthetic versions used in the experiment obtained lower classifications than their natural counterparts, the data suggests that the gap between synthetic and real gestures is the smallest while the synthetic voice is the furthest from its natural version. Furthermore, when we used the synthetic voice, the facial expressions of both characters (the virtual and the real) were rated worse than with the real voice. This effect was not significant for the gestures, thus suggesting that the importance of building synthetic voices as natural as possible is extremely important as it impacts in the perception of other means of communication (such as the perception of the facial expression).

It's All in the Anticipation

Abstract: Since the beginnings of character animation, anticipationhas been an effective part of the repertoire of tricks used to create believable animated characters. However, anticipation has had but a secondary role in the creation of synthetic virtual life forms. In this paper, we describe how a simple anticipatory mechanism that generates an affective signal resulting from the mismatch between sensed and predicted values -- the emotivector-- can help in the creation of consistent believable behaviour for intelligent virtual characters.

I-Sounds

Abstract: I-Sounds aims to increase the Affective Bandwidth of an Interactive Drama system called I-Shadows, implementing a fully emergent system that generates affective music, based on musical theory and on the emotional state of the characters.

From IVAs to Comics Generating Comic Strips from Emergent Stories with Autonomous Characters

Abstract: Emergent narrative systems create stories which are always different from each other. Creating summaries of these stories is a challenge especially if we want to capture the richness of the characters. Our goal is to automatically generate summaries from emergent narrative using comics as the visual medium for the summary. We identify the most important situations in the story log looking at the emotional state of the characters, transform the resulting summary into a comics description and create the comic. We believe that a good summarization of a story that maintains the emotions of the characters together with an expressive visual representation is essential for the user to remember the story.