Improv is a system for the creation of real-time behavior-based animated actors. There have been several recent efforts to build network distributed autonomous agents. But in general these efforts do not focus on the author's view. To create rich interactive worlds inhabited by believable animated actors, authors need the proper tools. Improv provides tools to create actors that respond to users and to each other in real-time, with personalities and moods consistent with the author's goals and intentions. Improv consists of two subsystems. The first subsystem is an Animation Engine that uses procedural techniques to enable authors to create layered, continuous, non-repetitive motions and smooth transitions between them. The second subsystem is a Behavior Engine that enables authors to create sophisticated rules governing how actors communicate, change, and make decisions. The combined system provides an integrated set of tools for authoring the "minds" and "bodies" of interactive acto...

This paper describes methods and data structures used to leverage motion sequences of complex linked figures. We present a technique for interpolating between example motions derived from live motion capture or produced through traditional animation tools. These motions can be characterized by emotional expressiveness or control behaviors such as turning or going uphill or downhill. We call such parameterized motions "verbs" and the parameters that control them "adverbs." Verbs can be combined with other verbs to form a "verb graph," with smooth transitions between them, allowing an animated figure to exhibit a substantial repertoire of expressive behaviors. A combination of radial basis functions and low order polynomials is used to create the interpolation space between example motions. Inverse kinematic constraints are used to augment the interpolations in order to avoid, for example, the feet slipping on the floor during a support phase of a walk cycle. Once the verbs and...

Recent years have witnessed the birth of a new paradigm for learning environments: animated pedagogical agents. These lifelike autonomous characters cohabit learning environments with students to create rich, face-to-face learning interactions. This opens up exciting new possibilities; for example, agents can demonstrate complex tasks, employ locomotion and gesture to focus students'attention on the most salient aspect of the task at hand, and convey emotional responses to the tutorial situation. Animated pedagogical agents offer great promise for broadening the bandwidth of tutorial communication and increasing learning environments' ability to engage and motivate students. This article sets forth the motivations behind animated pedagogical agents, describes the key capabilities they offer, and discusses the technical issues they raise. The discussion is illustrated with descriptions of a number of animated agents that represent the current state of the art.

Real-time control of three-dimensional avatars is an important problem in the context of computer games and virtual environments. Avatar animation and control is difficult, however, because a large repertoire of avatar behaviors must be made available, and the user must be able to select from this set of behaviors, possibly with a low-dimensional input device. One appealing approach to obtaining a rich set of avatar behaviors is to collect an extended, unlabeled sequence of motion data appropriate to the application. In this paper, we show that such a motion database can be preprocessed for flexibility in behavior and efficient search and exploited for real-time avatar control. Flexibility is created by identifying plausible transitions between motion segments, and efficient search through the resulting graph structure is obtained through clustering. Three interface techniques are demonstrated for controlling avatar motion using this data structure: the user selects from a set of available choices, sketches a path through an environment, or acts out a desired motion in front of a video camera. We demonstrate the flexibility of the approach through four different applications and compare the avatar motion to directly recorded human motion.

The Behavior Expression Animation Toolkit (BEAT) allows animators to input typed text that they wish to be spoken by an animated human figure, and to obtain as output appropriate and synchronized nonverbal behaviors and synthesized speech in a form that can be sent to a number of different animation systems. The nonverbal behaviors are assigned on the basis of actual linguistic and contextual analysis of the typed text, relying on rules derived from extensive research into human conversational behavior. The toolkit is extensible, so that new rules can be quickly added. It is designed to plug into larger systems that may also assign personality profiles, motion characteristics, scene constraints, or the animation styles of particular animators.

Animated pedagogical agents that inhabit interactive learning environments can exhibit strikingly lifelike behaviors. In addition to providing problem-solving advice in response to students ’ activities in the learning environment, these agents may also be able to play a powerful motivational role. To design the most effective agent-based learning environment software, it is essential to understand how students perceive an animated pedagogical agent with regard to affective dimensions such as encouragement, utility, credibility, and clarity. This paper describes a study of the affective impact of animated pedagogical agents on students ’ learning experiences. One hundred middle school students interacted with animated pedagogical agents to assess their perception of agents ’ affective characteristics. The study revealed the persona effect, which is that the presence of a lifelike character in an interactive learning environment—even one that is not expressive— can have a strong positive effect on student’s perception of their learning experience. The study also demonstrates the interesting effect of multiple types of explanatory behaviors on both affective perception and learning performance.

This paper describes a framework that allows a user to synthesize human motion while retaining control of its qualitative properties. The user paints a timeline with annotations — likewalk, run or jump — from a vocabulary which is freely chosen by the user. The system then assembles frames from a motion database so that the final motion performs the specified actions at specified times. The motion can also be forced to pass through particular configurations at particular times, and to go to a particular position and orientation. Annotations can be painted positively (for example, must run), negatively (for example, may not run backwards) orasa don’t-care. The system uses a novel search method, based around dynamic programming at several scales, to obtain a solution efficiently so that authoring is interactive. Our results demonstrate that the method can generate smooth, natural-looking motion. The annotation vocabulary can be chosen to fit the application, and allows specification of composite motions (run andjump simultaneously, for example). The process requires a collection of motion data that has been annotated with the chosen vocabulary. This paper also describes an effective tool, based around repeated use of support vector machines, that allows a user to annotate a large collection of motions quickly and easily so that they may be used with the synthesis algorithm.

Modeling a city poses a number of problems to computer graphics. Every urban area has a transportation network that follows population and environmental influences, and often a superimposed pattern plan. The buildings appearances follow historical, aesthetic and statutory rules. To create a virtual city, a roadmap has to be designed and a large number of buildings need to be generated. We propose a system using a procedural approach based on L-systems to model cities. From various image maps given as input, such as land-water boundaries and population density, our system generates a system of highways and streets, divides the land into lots, and creates the appropriate geometry for the buildings on the respective allotments. For the creation of a city street map, L-systems have been extended with methods that allow the consideration of global goals and local constraints and reduce the complexity of the production rules. An L-system

This paper describes an agent-based approach to realizing interactive pedagogical drama. Characters choose their actions autonomously, while director and cinematographer agents manage the action and its presentation in order to maintain story structure, achieve pedagogical goals, and present the dynamic story to as to achieve the best dramatic effect. Artistic standards must be maintained while permitting substantial variability in story scenario. To achieve these objectives, scripted dialog is deconstructed into elements that are portrayed by agents with emotion models. Learners influence how the drama unfolds by controlling the intentions of one or more characters, who then behave in accordance with those intentions. Interactions between characters create opportunities to move the story in pedagogically useful directions, which the automated director exploits. This approach is realized in the multimedia title Carmen's Bright IDEAS, an interactive health intervention designed to impro...

this paper we discuss our research and development towards creating an architecture, and a story design using this architecture, that integrates a broad and shallow approach to natural language processing, a novel character authoring language and a novel drama manager, in order to build an interactive drama about human relationships. Faade: an experiment in interactive drama In Faade, you, the player, using your own name and gender, play the character of a longtime friend of Grace and Trip, an attractive and materially successful couple in their early thirties. During an evening gettogether at their apartment that quickly turns ugly, you become entangled in the high-conflict dissolution of Grace and Trips marriage. No one is safe as the accusations fly, sides are taken and irreversible decisions are forced to be made. By the end of this intense oneact play you will have changed the course of Grace and Trips lives motivating you to replay the drama to find out how your interaction could make things turn out differently the next time. Figure 1. Real-time rendered characters Grace and Trip in Faade, with player-typed text and hand cursor. Faade is an attempt to create a real-time 3D animated experience akin to being on stage with two live actors who are motivated to make a dramatic situation happen. Instead of providing the player with 40 to 60 hours of episodic action and exploration in a huge world, we want to design an experience that provides the player with 20 minutes of emotionally intense, unified, dramatic action. The player's actions should have a significant influence on what events occur, which are left out, and how the drama ends. The experience should be varied enough that it supports replayability; only af...