We have investigated the bottleneck in web-based MORPG system and proposed a load-distribution method using multiple web servers. This technique uses a dynamic data allocation method, called the moving home. This paper describes the evaluation of our method using 4, 8, 16 web servers. We evaluated it on both the single-server system and multi-server system. And we confirm that the effect of the moving home through the comparison between the multi-server system without the moving home and that with the moving home. Our experimental result shows that the upper bound of the number of avatars in the eight-server system with the moving home becomes 380 by contrast that in the single-server system is 200.

This letter proposes a prototyping tool for Web-based Multiuser Online Role-Playing Game (MORPG). The design goal is to make this tool simple and powerful. The tool is comprised of a GUI editor, a translator and a runtime environment. The GUI editor is used to edit state-transition diagrams, each of which defines the behavior of the fictional characters. The state-transition diagrams are translated into C program codes, which plays the role of a game engine in RPG system. The runtime environment includes PHP, JavaScript with Ajax and HTML. So the prototype system can be played on the usual Web browser, such as Firefox, Safari and IE. On a click or key press by a player, the Web browser sends it to the Web server to reflect its consequence on the screens which other players are looking at. Prospected users of this tool include programming novices and schoolchildren. The knowledge or skill of any specific programming languages is not required to create state-transition diagrams. Its structure is not only suitable for the definition of a character behavior but also intuitive to help novices understand. Therefore, the users can easily create Web-based MORPG system with the tool.

This letter presents the connectivity number of 1-voxels in a 3-D digitized binary picture, and gives the necessary and sufficient condition that a 1-voxel in a 3-D picture is deletable. A shrinking algorithm for a 3-D object is suggested by using these results.

This paper proposes a new emphasizing three-dimensional pointing device considering user friendliness and lack of cable clutter. The proposed method utilizes five degrees of freedom via the medium of non-verbal voice of human. That is, the spatial direction of the sound source, the type of the voice phoneme and the tone of the voice phoneme are utilized. The input voice is analyzed regarding the above factors and then taking proper effects as previously defined for human interface. In this paper the estimated spatial direction is used for three-dimensional movement for the virtual object as three degrees of freedom. Both of the type and the tone of the voice phoneme are used for remaining two degrees of freedom. Since vocalization of nonverbal human voice is an everyday task, and the intonation of the voice can be quite easily and intentionally controlled by human vocal ability, the proposed scheme is a new three-dimensional spatial interaction medium. In this sense, this paper realizes a cost-effective and handy nonverbal interface scheme without any artificial wearing materials which might give a physical and psychological fatigue. By using the prototype the authors evaluate the performance of the scheme from both of static and dynamic points of view and show some advantages of look and feel, and then prospect possibilities of the application for the proposed scheme.

This letter presents definitions of connectivity among volume cells of a three-dimensional (3-D) digitized binary picture, and an explicit formula to calculate the Euler number of a 3-D object in a given 3-D picture.

This paper reports our study of how to gain consistency of states in a ball-game typed Distributed Virtual Environment (DVE) with lag, in peer-to-peer (P2P) architecture. That is, we are studying how to reduce in real-time the difference of states between the participating terminals in a virtual ball game caused by transmission lag or update interval. We are also studying how to control shared objects in real-time in a server-less network architecture. Specifically, a priority field called Allocated Topographical Zone (AtoZ) is used in P2P for DVE. By implementing this function, each terminal can compute which avatar holds the ownership of a shared object by calculating mutually the state of the local avatar predicted by the remote terminals. The region for ownership determined by AtoZ allows an avatar to access and control an object dominantly, so that a geometrical property is dynamically changed depending upon the relative arrangement between the object and avatars. Moreover considering the critical case, defined as inconsistent phenomena between the peers, caused by the network latency, a stricter ownership determination algorithm, called dead zone is introduced. By using these protocols in combination, a robust and effective scheme is achieved for a virtual ball game. As an example of the application, a real-time networked doubles air-hockey is implemented for evaluation of the influence of these protocols on interactivity and on consistency.

We developed a Web-based education system called "Web-Com". It supports synchronous and asynchronous learning. It consists of an interactive web browser and voice server. Web-Com provides a multi-layer drawable canvas on which the user can draw annotations. Each layer can be shared with other users in real-time via the Internet to enable synchronous learning. In conjunction with the voice server, Web-Com can support voice communication. It can also replay the process of annotation in order, which enables asynchronous learning. Finally, a subject experiment is conducted to evaluate the scheme's workability and explore various issues that arise during the course of learning. The experimental results show that learners can learn fairly interactively with an instructor in a Web-Based class using Web-Com's synchronous style.

Performing a musical session via networks requires real-time interaction. There exists, however, the problem of delay between the network nodes, which causes musical sessions become an impediment. To overcome this problem, we have proposed a new protocol for musical session called Mutual Anticipated Session (M.A.S.), which is a type of ensemble that controls appropriate timing of sounds. In the M.A.S, one player's performance precedes the other players', thus this performance is called a "precedent musical performance," and we call a time lapse between the players' performance as "precedent time." In the current M.A.S, it is assumed that the tempo during the performance is constant. In such a case, however, players' requirements to perform more expressively or more emotionally by varying the tempo are sacrificed. Thus, in this paper, enhancement of function that accommodates changes of the tempo by predicting tendency of it is realized. Finally we evaluate the enhancement both by system performance test and by task performance of subject experiments.

An experimental test has been done on the suitability of box splines for the estimation of color images from their observation through the honeycomb color filter. The estimation is made by following the framework of consistent sampling by Unser and Aldroubi. Numerical evaluation of the estimation errors has shown that the best estimation may be made by choosing the box splines which are twice locally averaged along each of the three axes consisting of the unilateral triangular mesh. A close look at estimated images has indicated that those box splines are almost free from directional jaggy noises that the traditional B-splines suffer from.