Masatoshi Arikawa

Navitime: Supporting Pedestrian Navigation in the Real World

Almost 2 million Japanese citizens use Navitime, a mobile phone-based navigation service that incorporates various modes of transportation. User experiences reveal implications for designing urban-computing services. Location-based services are a key pervasive computing application that could deeply influence urban spaces and their inhabitants. Recent advances in mobile phones, GPS, and wireless networking infrastructures are making it possible to implement and operate large-scale location- based services in the real world.

Dynamic LoD for QoS management in the next generation VRML

A high speed computer network will provide us with new broadband multimedia applications. This paper discusses new functions for the next generation VRML (Virtual Reality Modeling Language) over high speed computer networks. The LoD (Level of Detail) of 3D objects is the most important function for rendering scenes dynamically while managing the QoS (Quality of Service). New requirements for the next generation VRML are discussed. We present Differential VRML (DVRML) in order to update scene graphs dynamically, and describe principles of the LoD function based on the DVRML.

An Intelligent System for Integrating Autonomous Nomenclature Databases in Semantic Heterogenity

We developed a new integration algorithm for autonomous nomenclature databases in the presence of semantic heterogeneity over international computer networks. First, the algorithm requires users to assign priority according to order of belief for each one of the accessible nomenclature databases. Integration is achieved by increasing the kernel database, selected by the algorithm as the one with the highest priority among the databases. Complex problems are included to recognize consistent parts that can be incrementally added to the kernel database in the remainder of the accessible nomenclature databases through the use of tree structures. The algorithm with relational operators, was proposed after considering both structural and cooperative constraints useful in managing single and multiple databases. In addition, we present a nomenclature database system including the useful algorithm. The system is also accessible from remote users through World-Wide Web and is implemented in SQL programming and CGI (Common Gateway Interface) scripts of World-Wide Web. The system can be useful in both integrating and managing biological taxonomy databases over international computer networks.

Spatial media fusion project

Most information includes some kinds of spatial data such as the address of a restaurant and the position of a person carrying a portable phone. The spatial data are useful as meta data of multimedia data because they provide spatial connections between multimedia data. The spatial data are called spatial keys because they join different contents with spatial relationships. The spatial media fusion project started last year (2000) to construct a framework of multimedia content circulation based on spatial keys. A geographic coordinate (x,y) is one kind of spatial data, but there are other kinds of spatial data, called spatial referenced data, which can be converted to geographic coordinates. We particularly focus on Japanese addresses and camera parameters as spatial referenced data. Using two kinds of spatial referenced data, we integrated text data and photo/video data in the form of spatial keys.

Dynamic maps as composite views of varied geographic database servers

This paper presents new style maps, called dynamic maps, based on view functions of geographic databases. The dynamic maps contain two basic components, (1) queries applied to geographic databases and (2) visualization methods for data derived by the queries. There are three major factors to change the content of dynamic maps, (1) data (unlike conventional geographic systems, we assume that up-to-date data are always used to generate maps), (2) query (a map for a specific purpose is generated by a query), (3) visualization method (even if a set of objects to be displayed is determined, the resulting map cannot be uniquely determined, since we have to distinguish important geographic objects and there is a limit caused by the size of a display). A prototype system GeoProxy was developed in order to prove that the dynamic maps are feasible and useful. This paper also describes the system organization and object management, and presents the demonstrations of interactions with users in GeoProxy.

Dynamic map synthesis utilizing extended thesauruses and reuse of query generation process

In this paper, we will discuss a map synthesis system which handles static information (geographic objects) as well as dynamic information (traffic conditions, weather, etc.). The system is considered to be general purpose and can generate arbitrary maps according to the user specification, It is very difficult for a user to specify a exact query which corresponds to the required map. Furthermore even selected objects are appropriate, the map may not be proper to be displayed. The system automatically generates missing information or find errors in the user specification. The result is feedback-ed to the user and further refinement is made. For the purpose we use geographic domain thesaurus which contains aggregation and other semantic relationships as well as conventional thesaurus hierarchy. Especially compatibility levels of objects play important roles to generate maps and ilnd errors in the specification, We will also discuss methods to reuse similar map generation processes.

A 3-D Photo Collage System for Spatial Navigations

This paper proposes a new style tool, a 3-D photo collage system, to manage new style of digital cities. This system allows ordinary people to create, publish, share and navigate pseudo 3-D spaces using perspective photos on the Web. We present a framework of the 3-D photo collage system and characteristics of a prototype system based on it. Finally, some experiments using it are shown.

A Dynamic QoS Adaptation Mechanism for Networked Virtual Reality

In this paper, we propose a dynamic QoS adaptation mechanism for the networked virtual reality (VR) system to improve responsiveness to the users and introduce a live video into an networked VR system. To keep presentation quality as much as possible from point of view of user’s perception when network and local system resources are going to starve, we introduce the notion of an importance of presence (IoP) of objects. In case of the resource starvation, our VR system reduces QoSs of both Computer Graphic (CG) objects and Video objects based on IoP. That is, the quality of the object whose IoP is the lowest in the virtual space is reduced.

Personal dynamic maps based on distributed geographic information servers

Current commercial computer maps, including the maps of car navigation systems, have become popular. They are basically an extension of conventional paper maps and do not make use of computer networks. This paper presents new style maps, called dynamic maps, which are based on the view functions of geographic databases. The dynamic maps are defined by two components: (1) queries to geographic databases; and (2) visualization methods for data derived by the queries. The dynamic maps provide three main characteristics: (1) specialized maps defined by ad hoc queries; (2) automatic updates of maps; and (3) adaptive changes of appearances of maps.<<ETX>>

A ubiquitous photo mapping considering users' lines of sight

This paper proposes a new framework for mapping and retrieving photographs, maps and cyberspaces to each other. Our target photographs are enhanced with spatial metadata such as geographic coordinates where they were taken and directions where they focused on. We assume photographs having such spatial metadata become popular. In a common framework, such photographs are mapped to their viewpoints by using their location information generated by GPS. We think this framework has less function for practical spatial queries. For example, even if a photograph is mapped to a certain point on a map, a scene of the point may not be shown in the photograph. It may show a different direction than user wants to see. A problem is that though locations or objects shown in photographs are important for users, viewpoints are not positions of them but positions of cameras from which photographs were taken. We therefore map each photograph to a vector from its viewpoint to its gazing point, and named the vector as photo vector. A prototype system based on our framework provides functions such as handling advanced spatial queries for retrieving photographs, visualizing how many photographs show each location, and mapping text labels having URLs and geographic coordinates to the appropriate positions on photographs. In this framework, photographs, maps and cyberspaces are mapped to each other.