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1. An Architecture for Character-Mediated Interactive Presentations
Rossana Damiano1
, Francesca Biral2
, Vincenzo Lombardo1
, Antonio Pizzo2
1
Dipartimento di Informatica and Centro di Scienza Cognitiva, Università di Torino
c.so Svizzera 185, Torino, Italy
{vincenzo, rossana}@di.unito.it
2
Dipartimento di Discipline Artistiche, Musicali e dello Spettacolo, Università di Torino
via S. Ottavio 9, Torino, Italy
{antonio.pizzo, francesca.biral}@unito.it
Abstract. In this paper, we present the architecture of Cyrano, a system for character-based, drama-like
interactive information presentation in the specific domain of cultural heritage. The theoretical approach,
which follows the interactive drama paradigm, responds to a well-documented need for a drama-based
metaphor to deal with cultural heritage presentation issues. Cyrano is implemented on a PDA-wireless
network infrastructure adapted to the constraints of an historical site environment, and takes into account
visitors’ requirements, as described in literature on PDA applications in museums and historical sites.
1. Introduction
In recent years, much attention has been devoted to artificial characters as a valuable communication metaphor
in information presentation (see papers in Cassel et al. 2000): character-mediated presentations are considered to
be more compelling, especially if they are delivered in the form of drama and entertainment (Gershon & Page
2001). The dramatic component is fundamental, since, as Picard points out (Picard 1997), an appropriate and
well-calibrated level of emotional arousal helps focalizing the attention and facilitates the understanding.
In this paper, we present the architecture of Cyrano, a system for character-based information presentation based
on an interactive drama paradigm (Kelso et al. 1992, Mateas 2001& 2002). Interactive drama relies on believable
agents, i.e. “broad” and shallow agents which display a range of abilities (including reactivity, emotions, social
and language skills) that convey the user the illusion of reality and allow for her/his suspension of disbelief. This
paradigm, created for entertainment purposes, provides a valuable tool in the application design of electronic
guidebooks, an area where research on interaction metaphors is so far lacking.
Cyrano generates interactive presentations acted out by an artificial character who inhabits a virtual space
situated on a portable device. The system architecture, typical of BDI agents, exploits a repository of pre-built
script-units, that can be combined in order to react efficiently to the user’s inputs, mainly speech (natural
language) and hardware buttons pressing. The motivation for having pre-built script-units is that the simulation
of multimodal systems and their synchronization is a very costly task, and their on-line generation may be
ineffective at the current state of the art, i.e. characters may appear un-reactive if not “dumb” (Cassel et al.
2000), therefore conflicting with the interactive drama paradigm.
The paper is organized as follows: in the next section after a brief survey of electronic guidebook applications
we point out the lack of a communication metaphor in the application design; then we illustrate the Cyrano
architecture; finally, we show a quick overview of the DRAMA-Tour application, developed in the context of an
historical site.
2. The context: a brief survey of PDA applications in museums and historical sites
Applications featuring hand-helds in a museum context date as far back as 1993, the year the first P.D.A.
(Personal Digital Assistant), the Apple Newton, was launched on the market. Major drawbacks reportedly cursed
early prototypes: the Newts were heavy, fragile, expensive and museum staff was even reluctant to give them out
fearing “equipment malfunction and theft” (Amirian 2001). The same range of problems, though, can be
encountered in reviewing even recent applications: PDAs are still quite expensive, fragile and their use in a
museum context can prove a real challenge for designers and visitors (Electronic Guidebook Forum, 2001).
Nevertheless, the PDA has been labelled the next killer app in museums (Schwarzer 2001). Research on the
subject is thriving. Computer scientists and the IT community in general regard the museum visitor as the typical
specimen of mobile computing user. Since research on the subject mainly streams from the concern of testing
emerging technologies such as wireless networks and mobile computing devices, the museum is often regarded
as the mere environment where to test a one-off, short-lived prototype. However, museums strive to attract a
larger, and more socially diverse, public, as their role in modern society is shifted from being a repository to

2. being communicator of culture. The most enlightened museum directors and curators are aware of the challenges
this role shift involves and look upon technology as a useful tool to implement effective communication
strategies. Spalding has vividly described a futuristic scenario where museums take advantage of mobile
computing technologies in order to efficiently perform story-telling on the invaluable and fascinating objects that
they own (Spalding 2002).
The technological possibilities to make Spalding’s scenario come true already exist (see Biral & Lombardo
2003) for a review. However, there is a need to further investigate the application design in the terms of
constructing an effective metaphor for the visit. Most applications do not feature a general metaphor for the visit
and rely on a browser metaphor for the interface design, a choice liable of generating confusion for the user, e.g.
reportedly, users who followed links to exhibitions they were not at experienced a “lost in hyper-reality”
phenomenon (Fleck et al. 2002).
Xerox PARC researchers can be said to be the only team who has come up with an effective metaphor for hand-
helds use in a museum context (historical site). They adopted an innovative perspective by giving the electronic
guidebook a conversationalist role, in order to enhance socialisation between visiting companions, and
developed a prototype that permitted eavesdropping on the audio content of a companion's guidebook. The
conversationalist metaphor (and eavesdropping) proved effective for “building stronger interactional ties
between companions (encouraging more natural conversations) as well as increasing awareness of the room and
its contents” (Grinter et al. 2002).
Moving on from this successful conversationalist metaphor we are developing an application for an historical
site visit where the ‘conversationalist’ is embodied in an artificial character who, according to loose dramatic
constraints, performs the role of a former inhabitant of the site. A drama-based metaphor is able to address
critical problems in the often “lifeless” and “squalid” presentation of cultural heritage sites (Waterfield, 1998). It
is well-known that theatre is an ideal metaphor to enhance visits in an historical site setting, as it is currently
used in exhibition design at various levels, because of the intrinsic, mute nature of objects (Maure, 1995).
Moreover, costume drama and ‘ghost’ performances, massively employed in historical sites, heritage centres,
period rooms and the like to “bring the past back to life” are hugely popular amongst the public, although at
times criticized by historians on account of being attempts in re-writing history more than re-enacting it
(Buckley 1996).
3. System architecture
The system is intention-driven, as the interactional and dramatic goals of the system are explicitly represented,
and drive the behaviour generation process. The system works by selecting a script according to its presentation
goals (Cohen & Levesque 1990, Bratman et al. 1988) and monitoring its execution so as to react to user input
(Wooldridge & Parsons 1999). A script consists of a sequence of pre-recorded audiovisual units (script-units), a
set of pre-conditions, that determine the applicability of the script, and a set of effects, that hold after the script
execution. Scripts are stored in a script library, the Script-KB (see Figure 1). The system is reactive: if the current
script - previously selected as contextually appropriate to the system goals - is not appropriate anymore, the
system switches to a new script. However, the system can react only within a set of well-identified conditions, in
order to preserve the dramatic coherence encoded in scripts by the application designer. During the deliberation
phase, the system will abandon the execution of the current script only if a set of “interrupt” conditions hold: if
the user has abruptly changed location or has shifted attention through the appropriate input devices. Now we
first describe the basic structure of script-units and then the Cyrano architecture.
Proceeding bottom-up, we define Clip any multimedia item, containing audio-video information, graphics or
animation. A Script-unit is an elementary behavioral unit featuring a single character (Character clip), plus any
additional audio-visual information (e.g. Context-clips provide extra information, like background or sound
effects). Script units are concatenated to form sequences (Scripts in the system terminology) by interleaving
Script-units and Transitions-units. The role of Transition-units is twofold: they produce the system behavior
while waiting for the user input, and guarantee a smooth transition between subsequent Character-clips. In this
way, the developer is not constrained to worry about graphical coherence when designing Character-clips, and
Character-clips can be sequenced to form different Scripts with some degree of freedom.
The system architecture is structured as a cascade of modules (see Figure 1). Each module takes into account the
output representation of the previous module and the interaction already occurred in the current session
(interaction history - IH), and produces a new representation while upgrading the interaction history.
The Input Manager takes as input various signals from the input devices (user requests expressed via
text/speech, tapping, buttons, and the information about the device current location), and converts it into a logic
representation. Based on this representation, the Understanding Module identifies the user's goals: for example,
the user may desire to obtain more information about a certain item (information seeking goals), ask for
clarification about a system turn (interaction handling goals), or simply signals the willing to attend the
remaining presentation. Then, the Goal Manager generates the system goals in response to the identified user’s

3. goals by consulting the Goal-KB, a set of rules which select the interactional and dramatic goals of the system
based on the interaction context and on the advancement of the drama.
The Script Manager, the deliberative core of the system, exploits the knowledge encoded in the Script-KB, and
the input from the previous modules (Interaction History, User’s and System’s goals) to deliberate about the
currently selected script, by continuing its execution with the next script-unit, switching to a new script, or
retrieving a script (if no script has been previously selected). If a new script has to be selected, the Script
Manager consults the Script-KB in search for a new script with applicable preconditions. Finally, the
Presentation Module identifies a suitable transition (transition-unit) from the previous script-unit to the current
one. The Action Scheduler receives a pair <transition-unit, script-unit> from the Presentation Module and
dispatches it to the multimedia output devices for synchronised execution.
Figure 1: Architecture of the Cyrano system
4. An application in an historical site context
We are currently developing a prototype application for the visit of the Appartamenti Reali de La Mandria
(Royal Apartments of La Mandria) in Venaria, Turin, Italy. It is a bourgeois 14-room apartment where Vittorio
Emanuele II, the first of re-united Italy’s kings, spent 30 years. The application infrastructure is made of PDAs
(equipped with head-phones and micro-phones) and a wi-fi LAN, with all the pre-packed clips residing on the
PDAs and all the architectural components hosted on the site’s server. We have relinquished plans to tag
Input devices:
LOCATION
PEN POINTING
SPEECH
BUTTONS
Input
Manager
Understanding
Module
Goal
Manager
Script
Manager
Action
Scheduler
Output devices:
CHAR ANIMATION
GRAPHICS
SPEECH
TEXT
Hardwired reactions
Presentation
Module
GOAL-
KB
System
Goal
SCRIPT-KB
User
Goal
Script-unit
Input
Representation
Transition-unit +
Script-unit
Units
Execution
Interaction
History
TRANSITIONS
POOL

4. individual exhibits (a solution that is seldom feasible in historical sites) and settled on a more coarse-grained
localisation mechanism that uses strength of wi-fi signal (closeness to access points) to triangulate the visitor’s
location. On perceiving the visitor’s location the system executes one of the Scripts relative to the Goal of
presenting that particular location.
We provide here a brief example of a drama-based presentation of a room in the king’s residence, the Billiards
Room. In the system execution the current location of the user is the Billiards Room; the current system goal is
the presentation of the Billiards Room where this presentation can be conveyed throughout several Scripts.
We describe the Script-units of a specific Script, called “PlayBilliards”, where the king character Vittorio
Emanuele II exhibits a playful and competitive attitude towards the user. Let L.S., M.S. and C.U. stand for long
shot, medium shot and close-up, respectively. The description of the first Script-unit and the following
Transition-unit are in figures 2 and 3 (see the pictures from our Macromedia Flash implementation).
SCRIPT UNIT 1
CONTEXT CLIP CHARACTER CLIP
THE KING ENTERS
FROM RIGHT AND
STOPS IN THE MIDDLE
OF THE STAGE
START
M.S. OF THE KING
WITH BILLIARDS CUE
IN HIS HANDS
THE KING
DO YOU PLAY BILLIARDS? BODY
A WALZER MUSIC.
BACKGROUND:
BILLIARD ROOM
TAPESTRY
THE KING RAISES HIS
EYEBROW QUIZZICALLY
(M.S.)
END
Figure 2 –Script-unit 1 and three frames from the Character clip.
TRANSITION UNIT 1: LOOPABLE CLIP “CHALK”
CONTEXT CLIP CHARACTER CLIP
THE KING HAS HIS
EYEBROW RAISED
QUIZZICALLY
(C.U.)
START
THE KING PUTS CHALK ON
THE TOP OF HIS
BILLIARD CUE
BODY
BACKGROUND:
BILLIARD ROOM’S
TAPESTRY
“EMPTY CLIP” END
Figure 3 – Start-clip and Body-clip for Transition-unit 1
The Body-clip of Transition-unit 1 is a Loopable-clip, that takes into account the user’s interaction time (in this
case the system awaits for a positive or negative answer) and the eventual inertia of the system in calculating the
best dramatically suited Script-unit to follow in response of the user’s selection.

5. 5. Conclusions
The functioning of the system is modelled on the the way script writers work. The task of writing a drama can be
divided into two main steps: the author first creates the characters by implicitly defining their behavior in a given
set of situations, then sets up a sequence of events to which they react, thus obtaining the drama. Similarly, in
our system, the developer of a drama application first encodes the system's possible behaviors into a set of
scripts, leaving to the system the task of generating an intentional behavior by selecting a script among the
available ones.
From the viewpoint of the development of applications, this approach presents some advantages which derive
from its resemblance to the human authoring process. At the script-unit level, encoding the system's behavior
into pre-built, elementary units, enforces the tendency of script writers to reason in terms of complex behavioral
units, and, at the same time, it alleviates the difficulty of generating basic behaviors through a number of
coordinated cognitive system. At the script level, the necessity to organize the behavioral units into a coherent
sequence, allows the developer to follow those well-established narrative and interactional macro-structures
which drive both the authoring and understanding processes.
The obvious drawback of this approach is that the system, due to the prominent role of off-line behavior
definition, manifests a certain amount of rigidity with respect to the agent-based systems, like Oz (Mateas 2001,
2002).
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