Challenges to deliver 2D/3D content for multimedia applications in mobile environments

In the context of multimedia and hypermedia systems, the aspect of including mobile links to a stationary infrastructure and the use of mobile data terminals are gaining increasingly in importance. The current advancements of hardware, software, and telecommunications technology allow multimedia systems to be implemented in mobile environments. Nevertheless, in order to fully reach that goal and to meet the end-users’ expectations, specific limitations and usage scenarios of mobile environments have to be taken into consideration. This paper will give a definition of "multimedia" and will describe its major aspects completeness, integration, quality, and interaction which have to be taken into consideration by the implementation of a multimedia system. By using this approach it is possible to classify and to design multimedia applications, both from a technology centered as well as a human centered point of view. After presenting these aspects, a scheme for media representation levels is discussed. This scheme distinguishes between different l ve s of abstractions for media data and it shows a method to analyze different media representations and to describe the features and limitations of each of these levels. This is for example the basis for the distinction between raster and vector graphics formats which will be the main focus in the following parts of the paper. In the case of 2D/3D graphics and animation a new concept is presented for the integrated handling of these media data. The concept of an integrated scene graph and its application in a mobile map service is discussed. The integrated scene graph and its usage as a plugin inside a WWW-based browser allows the creation of new, gr aphics-based services, customized for a mobile platform. The different features introduced by the implementation effort are described, e.g., the overlay and tiling concept, and support for animation on-demand. The plugin is used by the "City Information Service" which is part of the MOMENTS project (AC002, Mobile Media and ENTertainment Services). Besides the handling of 2D/3D graphics and animation, the plugin allows the specification of different interactions for the mobile user. On one hand, interactions adopted to the "City Information Service", e.g., navigation within the maps can be defined. On the other hand interactions can be specified directly in the 3D vector graphics file since those data does not only allow the description of the geometry but can also include their "selfdynamic" and behavior in regard to user interactions. Besides its use as an enhanced viewer for map material, the plugin concept and its implementation can also be adopted for other types of services dealing with 2D and/or 3D vector graphics, up to mobile virtual environments. For this, d ifferent profiles concerning the usage of VRML 2.0, the "Virtual Reality Modeling Language", have to be taken into consideration. We present different content creation and conversion tools which are used for automatic creation of mobile services. These tools can be integrated into the server infrastructure and have been used for automatic graphics and animation creation, as well as the adoption of existing media to the requirements of mobile services. Finally we provide a conclusion and show up directions for future work.