A Multi-client architecture for hybrid terrain rendering on mobile devices

Abstract

Mobile devices such as Personal Digital Assistants (PDAs) or smart phones are rapidly increasing their graphics and networking capabilities. However, real-time rendering of large terrains is still a challenging task to accomplish in such limited devices. In this paper we describe the principles involved in the design and development of a scalable client-server architecture for hybrid rendering of terrains over wireless networks on mobile devices. We have developed a hybrid adaptive streaming and rendering method based on a server-client approach. The rendering workload is distributed between a server and the clients and the terrain is partitioned into the close-range geometry and the background. The close-range geometry is downloaded from the database and rendered on the mobile client, and the background is portrayed as a view-dependent panoramic impostor and rendered by the server on demand then it is sent on request to the server for display. The system architecture is organized in three levels: the main server, the panorama server and the mobile device client. This architecture provides support for efficient delivery of geometry and impostors to mobile clients according to their capabilities. As a proof of concept, we have implemented a prototype and carried out exhaustive experiments considering different network scenarios and different number of connected clients. The analysis of the server workload and response times shows that our architecture achieves a great scalability and performance even when using low-end mobile devices.