future work will likely involve some degree of automated
reconfiguration of a virtual world.
Experience Adaptation is not Interactive Storytelling. Interactive
Storytelling systems demonstrate how players or learners may
interact with story and scenario content in complex simulation
environments. Typically, an intelligent agent called a Drama
Manager adjusts the virtual environment – including the
behaviors of virtual characters – during execution to meet
dramatic or learning objectives. See Roberts and Isbell [12] and
Riedl et al. [10] for an overview of interactive storytelling and
drama management systems. The distinction between Experience
Adaptation and Interactive Storytelling is that in Interactive
Storytelling adjustments to the virtual world occur at execution
time in order to cope with the real-time actions of the player.
Experience Adaptation, on the other hand, “rewrites” the
objectives of the virtual environment in an offline process. In this
light, Experience Adaptation and Drama Management are
complimentary: the Experience Adaptor configures the Drama
Manager, which oversees the user’s interactive experience.
The Drama Management technique known as Narrative
Mediation is especially relevant. The Automated Story Director
framework [10] in particular makes partially ordered plans
interactive by generating branches and rendering storyline events
into goals that dictate the behaviors of semi-autonomous character
agents. We envision systems such as this can be used in
conjunction with Experience Adaptation to deliver highly
individualized, interactive experiences.
As an offline procedure, Experience Adaptation is a form of story
generation. Story generation is the process of automatically
creating novel narrative sequences from a set of specifications.
The most relevant story generation work is that that uses planning
as the underlying mechanism for selecting and instantiating
narrative events (c.f., [7, 4, 11]). The distinction between our
Experience Adaptor and story planning is that the Experience
Adaptor starts with a complete, sound narrative structure and is
capable of removing events.
4. CONCLUSIONS
This paper addresses the problem of leveraging human-authored
content in order to scale-up the applicability of virtual
entertainment experiences. We assume that experiences are
narratives that describe how the experience is expected to unfold.
We introduce the concept of employing an offline process to
customize experience specifications. Specifically, a player model
determines the desired features of a real-time experience and an
Experience Adaptor automatically customizes a hand-authored
storyline accordingly. To that end, we draw heavily from recent
work on search-based narrative generation, although adaptation is
necessarily different due to the fact that it starts with a complete,
human-authored narrative.
While this paper focuses on offline aspects of Experience
Adaptation, the process is in service of creating compelling
interactive, real-time experiences. Interactive real-time
experiences require autonomous believable characters and the
ability to dynamically adapt the storyline to accommodate the
user’s moment-to-moment decisions. Future work considers the
use of interactive narrative techniques such as that of Riedl et al.
[10], which uses a combination of dynamic narrative re-planning
and semi-autonomous character agents to create a real-time
experience. Ultimately, we believe that a combination of offline
and online AI processes will be required to solve the general
problem of customizing interactive entertainment experiences. As
on-demand and just-in-time entertainment computing becomes
reality, the greater the need for autonomous systems capable of
creativity and expressivity.
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