A framework for interactive responsive animation

The availability of high‐performance 3D workstations has increased the range of application for interactive real‐time animation. In these applications the user can directly interact with the objects in the animation and direct the evolution of their motion, rather than simply watching a pre‐computed animation sequence. Interactive real‐time animation has fast‐growing applications in virtual reality, scientific visualization, medical training and distant learning. Traditional approaches to computer animation have been based on the animator having complete control over all aspects of the motion. In interactive animation the user can interact with any of the objects, which changes the current motion path or behaviour in real time. The objects in the animation must be capable of reacting to the user's actions and not simply replay a canned motion sequence. This paper presents a framework for interactive animation that allows the animator to specify the reactions of objects to events generated by other objects and the user. This framework is based on the concept of relations that describe how an object reacts to the influence of a dynamic environment. Each relation specifies one motion primitive triggered by either its enabling condition or the state of the environment. A collection of the relations is structured through several hierarchical layers to produce responsive behaviours and their variations. This framework is illustrated by several room‐based dancing examples that are modelled by relations. Copyright © 2000 John Wiley & Sons, Ltd.     

Hybrid motion graph for character motion synthesis

ObjectiveThis paper proposes a novel framework of Hybrid Motion Graph (HMG) for creating character animations, which enhances the graph-based structural control by motion field representations for efficient motion synthesis of diverse and interactive character animations.MethodsIn HMG framework, the motion template of each class is automatically derived from the training motions for capturing the general spatio-temporal characteristics of an entire motion class. Typical motion field for each class is then constructed. The smooth transitions among motion classes are then generated by interpolating the related motion templates with spacetime constraints. Finally, a hybrid motion graph is built by integrating the separate motion fields for each motion class into the global structural control of motion graph through smooth transition.ResultsIn motion synthesis stage, a character may freely ‘switch’ among different motion classes in the hybrid motion graph via smooth transitions between motion templates and ‘flow’ within each class through the continuous space of motion field with agile and the continuous control process.ConclusionExperimental results show that our framework realizes the fast connectivity among different motion classes and high responsiveness and interactivity for creating realistic character animation of rich behaviors with limited motion data and computational resources.     

The virtual interactive presenter: a conversational character for interactive television

This paper describes the development of a conversational interface for interactive TV. With the advent of multi-channel digital TV, accessing Electronic Programme Guides (EPGs) will become increasingly complex. We claim that a conversational interface can support incremental refinement of user selections, thus assisting user choice without requiring extensive knowledge of the editorial categories used in the EPG. We present the system architecture and describe the building blocks of this system in terms of underlying technologies, namely speech recognition, Natural Language Processing, dialogue modelling, character animation and multi-modal presentation. The use of an animated character appears to influence the implementation of each of these basic techniques. After giving an overview of the system behaviour and architecture, we describe the various building blocks of a conversational agent as implemented in our system and to what extent each of the underlying technologies are influenced by the use of a conversational character. We report current results by describing example dialogues from the system. Finally, we compare our approach with other interface agents' paradigms.     

A preliminary poetics for interactive drama and games

Interactive drama has been discussed for a number of years as a new AI-based interactive experience. While there has been substantial technical progress in building believable agents and some technical progress in interactive plot, no work has yet been completed that combines plot and character into a full-fledged dramatic experience. Part of the difficulty in achieving interactive drama is due to the lack of a theoretical framework guiding the exploration of the technological and design issues surrounding it. This paper proposes a theory of interactive drama integrating Laurel's Aristotelian structural model with Murray's concept of agency. The resulting theory illuminates the general conditions under which a user will experience agency in any interactive experience and provides design and technology guidance for the particular case of building interactive dramatic worlds.     

Gated neural network framework for interactive character control

Multimedia Tools and Applications - Recently, interactive character control models based on neural network have become a hot research topic in computer graphics and motion synthesis. A real-time...     

4D video textures for interactive character appearance

4D Video Textures (4DVT) introduce a novel representation for rendering video‐realistic interactive character animation from a database of 4D actor performance captured in a multiple camera studio. 4D performance capture reconstructs dynamic shape and appearance over time but is limited to free‐viewpoint video replay of the same motion. Interactive animation from 4D performance capture has so far been limited to surface shape only. 4DVT is the final piece in the puzzle enabling video‐realistic interactive animation through two contributions: a layered view‐dependent texture map representation which supports efficient storage, transmission and rendering from multiple view video capture; and a rendering approach that combines multiple 4DVT sequences in a parametric motion space, maintaining video quality rendering of dynamic surface appearance whilst allowing high‐level interactive control of character motion and viewpoint. 4DVT is demonstrated for multiple characters and evaluated both quantitatively and through a user‐study which confirms that the visual quality of captured video is maintained. The 4DVT representation achieves >90% reduction in size and halves the rendering cost.     

Re-using digital narrative content in interactive games

This paper presents a model, called Scene-Driver, for the re-use of film and television material. We begin by exploring general issues surrounding the ways in which content can be sub-divided into meaningful units for re-use and how criteria might then be applied to the selection and ordering of these units. We also identify and discuss the different means by which a user might interact with the content to create novel and engaging experiences. The Scene-Driver model has been instantiated using content from an animated children's television series called Tiny Planets, which is aimed at children of 5–7-year old. This type of material, being story-based itself, lends itself particularly well to the application of narrative constraints to scene reordering, to provide coherence to the experience of interacting with the content.We propose an interactive narrative-driven game architecture, in which a user generates novel narratives from existing content by placing “domino” like tiles. These tiles act as “glue” between scenes and each tile choice dictates certain properties of the next scene to be shown within a game. There are three different game-types, based on three different ways in which tiles can be matched to scenes. We introduce algorithms for generating legal tile-sets for each of these three game-types, which can be extended to include narrative constraints. This ensures that all novel orderings adhere to a minimum narrative plan, which has been identified based on analysis of the Tiny Planets series and on narrative theories. We also suggest ways in which basic narratives can be enhanced by the inclusion of directorial techniques and by the use of more complex plot structures. In our evaluation studies with children in the target age-range, our game compared favourably with other games that the children enjoyed playing.     

Optimal and interactive keyframe selection for motion capture

Computational Visual Media - Motion capture is increasingly used in games and movies, but often requires editing before it can be used, for many reasons. The motion may need to be adjusted to...     

An interactive tool for mobile robot motion planning

This paper presents an interactive tool aimed at facilitating the understanding of several well-known algorithms and techniques involved in solving mobile robot motion problems. These range from those modelling the mechanics of mobility to those used in navigation. The tool focuses on describing these problems in a simple manner in order to be useful for education purposes among different disciplines. By highlighting interactivity, the tool provides a novel means to study robot motion planning ideas in a manner that enhances full understanding. Furthermore, the paper discuses how the tool can be used in an introductory course of mobile robotics.     

基于时间的角色动作调整方法

针对目前基于运动捕捉的角色运动控制方法中动作的不可调整问题,提出一种基于时间的角色动作调整方法。利用角色模型已有的基本动作,通过分析这些动作的时空特性得到动作各个阶段的时间参数;然后根据控制信息和环境约束,实时计算角色运动过程中的目标位置,再结合基本动作的时空特性,实时计算出运动关节参数,最终使角色能够在基本动作的基础上根据需要做出新动作。最后利用Unity平台加载角色模型,仿真实现了角色在转向和上台阶时腿部动作的调整过程。     

Sensuous Geographies: a multi-user interactive/ responsive installation

This paper discusses key issues which arose during the creation of Sensuous Geographies, a multi-user interactive/responsive installation created in 2003/4. In particular it will refer to the way in which the design of the installation was intended to draw attention to bodily sensation, facilitate collaborative interactivity between participants and bring about an emergent choreography, and to the collaborative methodology used in developing this work.     

Determination of camera parameters for character motions using motion area

We propose a method to determine camera parameters for character motion, which considers the motion by itself. The basic idea is to approximately compute the area swept by the motion of the character’s links that are orthogonally projected onto the image plane, which we call “motion area”. Using the motion area, we can determine good fixed camera parameters and camera paths for a given character motion in the off-line or real-time camera control. In our experimental results, we demonstrate that our camera path generation algorithms can compute a smooth moving camera path while the camera effectively displays the dynamic features of character motion. Our methods can be easily used in combination with the method for generating occlusion-free camera paths. We expect that our methods can also be utilized by the general camera planning method as one of heuristics for measuring the visual quality of the scenes that include dynamically moving characters.     

Interactive motion mapping for real‐time character control

It is now possible to capture the 3D motion of the human body on consumer hardware and to puppet in real time skeleton‐based virtual characters. However, many characters do not have humanoid skeletons. Characters such as spiders and caterpillars do not have boned skeletons at all, and these characters have very different shapes and motions. In general, character control under arbitrary shape and motion transformations is unsolved ‐ how might these motions be mapped? We control characters with a method which avoids the rigging‐skinning pipeline — source and target characters do not have skeletons or rigs. We use interactively‐defined sparse pose correspondences to learn a mapping between arbitrary 3D point source sequences and mesh target sequences. Then, we puppet the target character in real time. We demonstrate the versatility of our method through results on diverse virtual characters with different input motion controllers. Our method provides a fast, flexible, and intuitive interface for arbitrary motion mapping which provides new ways to control characters for real‐time animation.     

严肃游戏中虚拟角色行为建模综述

严肃游戏是计算机游戏一个新的发展方向,可以提供形象互动的模拟教学环境,已经广泛应用于科学教育、康复医疗、应急管理、军事训练等领域。虚拟角色是严肃游戏中模拟具有生命特征的图形实体,行为可信的虚拟角色能够提升用户使用严肃游戏的体验感。严肃游戏中的图形渲染技术已经逐步成熟,而虚拟角色行为建模的研究尚在初级阶段。可信的虚拟角色必须能够具有感知、情绪和行为能力。本文分别从游戏剧情与行为、行为建模方法、行为学习和行为建模评价等4个方面来分析虚拟角色行为建模研究。分析了有限状态机和行为树的特点,讨论了虚拟角色的行为学习方法。指出了强化学习的关键要素,探讨了深度强化学习的应用途径。综合已有研究,归纳了虚拟角色行为框架,该框架主要包括感觉输入、知觉分析、行为决策和动作4大模块。从情感计算的融入、游戏剧情和场景设计、智能手机平台和多通道交互4个角度讨论需要进一步研究的问题。虚拟角色的行为建模需要综合地考虑游戏剧情、机器学习和人机交互技术,构建具有自主感知、情绪、行为、学习能力、多通道交互的虚拟角色能够极大地提升严肃游戏的感染力,更好地体现寓教于乐。     

An interactive data-driven driving simulator using motion blending

Compared to the motion equations the data-driven method can simulate reality from sampling of real motions but real-time interaction between a user and the simulator is problematic. Existing data-driven motion generation methods simply record and replay the motion of the vehicle. Character animation technology enables a user to control motions that are generated by a motion capture database and an appropriate motion control algorithm. We propose a data-driven motion generation method and implement a driving simulator by adapting the method of motion capture. The motion data sampled from a real vehicle are transformed into appropriate data structures called motion blocks, and then a series of motion blocks are saved into the motion database. During simulation, the driving simulator searches for and synthesizes optimal motion blocks from the motion database and generates motion streams that reflect the current simulation conditions and parameterized user demands. We demonstrate the proposed method through experiments with the driving simulator.     

Procedural rhythmic character animation: an interactive Chinese lion dance

The creation of a stylistic animation through the use of high‐level controls has always been a design goal for computer animation software. In this paper, we propose a procedural animation system, called rhythmic character animation playacting (RhyCAP), which allows a designer to interactively direct animated characters by adjusting rhythmic parameters such as tempo, exaggeration, and timing. The motions thus generated reflect the intention of the director and also adapt to environmental obstacle constraints. We use a sequence of martial‐art steps in the performance of a Chinese lion dance to illustrate the effectiveness of the system. The animation is generated by composition of common motion elements, concisely represented in an action graph. We have implemented an animation control program that allows Chinese lion dance to be choreographed interactively. This authoring tool also serves as a useful means for preserving this part of world cultural heritage. Copyright © 2006 John Wiley & Sons, Ltd.     

A grasp‐based motion planning algorithm for character animation

The design of autonomous characters capable of planning their own motions continues to be a challenge for computer animation. We present a novel kinematic motion‐planning algorithm for character animation which addresses some of the outstanding problems. The problem domain for our algorithm is as follows: given a constrained environment with designated handholds and footholds, plan a motion through this space towards some desired goal. Our algorithm is based on a stochastic search procedure which is guided by a combination of geometric constraints, posture heuristics, and distance‐to‐goal metrics. The method provides a single framework for the use of multiple modes of locomotion in planning motions through these constrained, unstructured environments. We illustrate our results with demonstrations of a human character using walking, swinging, climbing, and crawling in order to navigate through various obstacle courses. Copyright © 2001 John Wiley & Sons, Ltd.