Autonomous pedestrians

We address the challenging problem of emulating the rich complexity of real pedestrians in urban environments. Our artificial life approach integrates motor, perceptual, behavioral, and cognitive components within a comprehensive model of pedestrians as individuals. Featuring innovations in these components, as well as in their combination, our model yields results of unprecedented fidelity and complexity for fully autonomous multihuman simulation in a large urban environment. We represent the environment using hierarchical data structures, which efficiently support the perceptual queries that influence the behavioral responses of the autonomous pedestrians and sustain their ability to plan their actions on local and global scales.     

An artificial life approach for the animation of cognitive characters

This paper addresses the problem of cognitive character animation. We propose the use of finite state machines for the behavioral control of characters. Our approach rests on the idea that the cognitive character arises from the evolutionary computation embedded in the artificial life simulation, which in our case is implemented by the finite state machine. We present some of the results of the WOXBOT/ARENA research project. This project to build virtual worlds is aimed at the graphic simulation of an arena, where small mobile robots can perform requested tasks while behaving according to their own motivation and reasoning. Each robot is an intelligent agent that perceives the virtual environment through a simulated vision system and reacts by moving away from or approaching the object it sees. The conception and specification of the robots and environment are being done very carefully to create an open distributed object architecture that could serve as a test-bed freely available and ready to use for testing theories in some computational areas such as evolutionary computation, artificial life, pattern recognition, artificial intelligence, cognitive neurosciences and distributed objects architectures. Furthermore, it is a first step towards building a cognitive animated character.     

Competition and evolution in virtual plant communities: a new modeling approach

This article presents studies on plants and their communities through experiments with a multi-agent platform of generic virtual plants. Based on Artificial Life concepts, the model has been designed for long-term simulations spanning a large number of generations while emphasizing the most important morphological and physiological aspects of a single plant. The virtual plants combine a physiological transport-resistance model with a morphological model using the L-system formalism and grow in a simplified 3D artificial ecosystem. Experiments at three different scales are carried out and compared to observations on real plant species. At the individual level, single virtual plants are grown in order to examine their responses to environmental constraints. A number of emerging characteristics concerning individual plant growth can be observed. Unifying field observation, mathematical theory and computer simulation, population level experiments on intraspecific and interspecific competition for resources are related to corresponding aggregate models of population dynamics. The latter provide a more general understanding of the experiments with respect to long-term trends and equilibrium conditions. Studies at the evolutionary level aim at morphogenesis and the influence of competition on plant morphology. Among other results, it is shown how the struggle for resources induces an arms race that leads to the evolution of elongated growth in contrast to rather ample forms at ground-level when the plants evolve in isolation.     

虚拟环境下并联坐标测量机几何建模与运动仿真

与普通直角型坐标测量机相比,并联坐标测量机具有结构简单、测量精度高、测头位姿灵活等一系列优点。但因该坐标测量机的驱动参量与测头输出位姿之间的非线性对应关系,致使其实体样机的设计工作变得十分复杂。该文以3-RPS型三自由度并联机构坐标测量机为研究对象。在虚拟环境下对其进行了三维实体造型和运动过程仿真,从而为新型坐标测量机实体样机的开发奠定了理论基础。     

The back-buffer algorithm: An extension of the radiosity method to dynamic environments

An efficient algorithm is introduced for the production of realistic image sequences of dynamic environments. The practicality of the radiosity method, which computes the interreflection of light within complex diffuse environments independent of viewpoint, is extended to dynamic environments where the paths of moving objects have been predefined. The algorithm takes advantage of the object coherence between static portions of an environment. A preprocessing stage executes once for a given image sequence and precalculates constant geometrical relationships in the environment. When the environment geometry changes, an update stage determines the global illumination using information provided by the preprocessor and the current positions of all moving objects. Test environments show speedups of at least twenty-five times over previous radiosity methods.     

Pen-to-mime: Pen-based interactive control of a human figure

In this paper a pen-based intuitive interface is presented, that controls a virtual human figure interactively. Recent commercial pen devices can detect not only the pen positions but also the pressure and tilt of the pen. We utilize such information to make a human figure perform various types of motions in response to the pen movements manipulated by the user. The figure walks, runs, turns and steps along the trajectory and speed of the pen. The figure also bends, stretches and tilts in response to the tilt of the pen. Moreover, it ducks and jumps in response to the pen pressure. Using our interface, the user controls a virtual human figure intuitively as if he or she were holding a virtual puppet and playing with it.

In addition to the interface design and implementation, this paper describes a motion generation engine to produce various motion based on varying parameters that are given by the pen interface. We take a motion blending approach and construct motion blending modules with a set of small number of motion capture data for each type of motions. Finally, we present the results from user experiments and comparison with a transitional gamepad-based interface.     

The use of virtual environments based on a modification of the computer game Quake III Arena in psychological experimenting

We investigated whether newly developed virtual 3D environments (VEs) based on a modification of the computer game Quake III Arena^® are suitable for psychological experimenting. Internal validity of data collected in VEs may be threatened due to a priori individual differences in general performance in VE navigation and in susceptibility to cybersickness. The main question was whether individual differences in performance can be diminished by means of training. Additionally, the susceptibility of different subsamples to cybersickness when moving within VEs was examined. 85 participants took part in an experiment where they had to fulfill simple tasks in three VEs. Navigation performance was measured as the time participants needed to make their way through the VEs. Differences in navigation performance between different levels of experience were diminished by training, indicating that internal validity can be obtained. A classification tree reveals that game-inexperienced female participants aged over 31 years have the highest risk of experiencing cybersickness. VEs based on modifications of computer games seem to be an extremely promising and inexpensive possibility for the administration of psychological experiments.     

Virtual marionettes: a system and paradigm for real-time 3D animation

This paper describes a computer graphics system that enables users to define virtual marionette puppets, operate them using relatively simple hardware input devices, and display the scene from a given viewpoint on the computer screen. This computerized marionette theater has the potential to become a computer game for children, an interaction tool over the Internet, enabling the creation of simultaneously viewed and operated marionette show by users on the World Wide Web, and, most importantly, a versatile and efficient professional animation system.