June 11, 2003
I just spent the last week in Stockholm as an invited opponent on a licentiate thesis in interactive drama. While there I was able to visit with a number of folks in the Swedish Institute for Computer Science, the IT University of Kista, and the mobility studio of the Interactive Institute.
A licentiate thesis is sort of a cross between a master’s degree and a Ph.D. proposal. Unlike the U.S. system, in which the questioning is done by a committee, in the Swedish system an external person is brought in to be an official Opponent. After the student’s presentation, the opponent gives a short presentation situating the student’s work in the field and then questions the student for 45 minutes or so. At the final Ph.D. defense, the opponent actually presents the work! The student is then given a few minutes to add any corrections to the presentation, then the opponent again questions the student for 45 minutes. The idea behind the opponent giving the presentation is that, in order to show that they are capable of asking good questions and being a worthy opponent, they should be able to present the student’s work in full detail. This makes sense, though it is obviously more work for the opponent. It was fun being an opponent on the licentiate thesis – I look forward to being an opponent on the full thesis.
The most interesting direction in Jarmo’s Laaksolahti’s thesis is his approach to drama management. Brenda Laurel, in her seminal thesis on interactive drama, introduced the abstract interactive drama architecture consisting of a simulation world containing autonomous characters, and a drama manager (she called it a Playwright) that observes the concrete activity in the simulation world and tweaks it to help make a story happen. The drama manager might manipulate the minds of the autonomous characters (e.g. giving them new goals, plans and motivations), change the physical world behind a player’s back (e.g. make a prop appear or disappear) or make an event happen (e.g. an explosion, rain, etc.). Building a drama manager involves figuring out how to represent the desired story, defining the set of drama manager moves with which the drama manager can manipulate the world, and defining a mechanism for computing a story policy. A story policy is a function that, given the history of activity in the story world so far, the representation of the desired story (or stories) and the collection of drama management moves, decides which move to make when. Some past approaches to drama management include:
- specifying an evaluation function that, given a total story sequence (at the scene level), returns a “goodness” rating. Given a partial, in progress story, game-tree search is used to project all possible story futures. The evaluations of the projected total stories are backed up (using average-max rather than mini-max) to assign ratings to the next possible drama manager moves (This method was developed in Peter Weyhrauch’s Oz Project thesis and introduced here).
- using a story-grammar-like rule system to specify the rules of “good” stories – the rule system filters the possible actions of the autonomous characters (e.g. ID Tension).
- distributing story knowledge among the story pieces (beats or scenes) and using this knowledge to maintain a probabilistic agenda of story moves (Andrew’s and my approach in Façade).
- the ever popular null drama manager, in which there is no drama manager, only a simulation world that the author tunes so as to make stories emerge (some problems with this approach are discussed on this thread).
- monolithic systems in which the story and characters are represented within a single framework, perhaps using planning to determine sequences of detailed character action necessary to make a story happen (Liquid Narrative, Erasmatron).
Jarmo’s approach is to represent the story as a finite state machine in which nodes correspond to scenes. Transitions are labeled with conditions over story state (including character state such as emotional state). The main new idea is to forward simulate the autonomous characters to determine if an undesired story state happens in the near future. If an undesired story state is likely to happen, the drama manager takes action to correct this state. What’s interesting about forward simulating the characters (running the autonomous characters faster than real time without effecting the world) is that the authorial work of specifying the characters is reused in drama management. The author spends a lot of effort to craft the personalities of the characters (typically in a reactive planning framework) such that their personalities manifest in their moment-by-moment interactions with the player. Then the author has to specify completely different knowledge at the story level to capture “goodness” of story (for the particular story world). It is interesting if the moment-by-moment knowledge encoded in the characters can somehow be reused at the story level for computing the drama management policy. Also, it makes intuitive sense that characters can help create a higher quality story experience by looking ahead at their own activity (planning is a special case of forward simulation). I and others have discussed this idea over the years, and Oz Project member Scott Neal Reilly even did some unpublished work in forward simulation of characters by combining Hap (a reactive planning framework for characters) with the Prodigy planner. But Jarmo’s work is the first published work I’ve seen pursing this idea specifically for drama management. While there are many conceptual difficulties to overcome, I look forward to seeing what Jarmo does with this idea.
During my trip I finally got to meet Jarmo’s advisor Kristina Höök, who I’ve known virtually for several years. Kristina has done interesting work in social navigation, and is currently interested in affective devices.
Jonas Söderberg at SICS has built magical devices for live role playing games. The magical devices include old spell books containing small computers and magic mirrors made out of flat-panel displays.
At the Mobility Studio of the Interactive Institute, I met with Liselott Brunnberg and Oskar Juhlin. They are currently working on portable devices for situated story generation and lightweight social interaction among bikers. In the story generation project, Lise is building a system that generates stories for children riding around in a car with their parents. As they drive around, the system incorporates the physical locations they pass in the car into the story. The biker project is grounded in an ethnographic study of social interaction among bikers on road trips. Oskar and I had a nice conversation about ethnography and design – I used to work as an ethnographer and concept designer at Intel Labs. We talked about how, in my current work in AI-based art, I’m hoping to bring ethnography back into my art practice by situating it relative to site-specific art, but where the site becomes a cultural rather than physical site.
I spent time hanging out with Loren Terveen, another opponent from the U.S. that Kristina had invited over for a different thesis. We had great fun together. One of the hilights of the trip was being taken herring fishing in the Baltic Sea by Kristina’s family. At this time of year the herring schools are so dense that you can pull three or four herring out at a time almost as fast as you drop the line in. Loren had the record in our boat by pulling out five at a time.