Representing Random Terrain on Resource Limited Devices

Random terrain generation is the procedural creation of a set of data that represents closely a believable landscape. Common techniques of achieving this include the use of fractals and noise. Such techniques usually require a large volume of memory, as the geometry of the terrain needs to be calculated and stored at run time. Given the limited memory available on mobile devices, such as mobile telephones, the storage of the data required to represent massive terrains can be difficult. In this paper, we propose a novel method of storing terrain data on devices with limited memory. This method involves placing pre-computed blocks of terrain, known as terrain tiles, together in a psuedo-random manner as governed by a noise function known as Perlin noise. This allows large amounts of terrain data to be represented while still giving the appearance of a randomly generated terrain. Traditionally, Perlin noise is used in the procedural generation of textures and the modeling of naturally occurring phenomena. Using Perlin noise, only a subset of the overall data generated by the function needs to be stored at any one time. The approach outlined in this paper associates a tile of terrain with each value generated by the Perlin Noise function, meaning that only a subsection of the total terrain is stored in memory at any one time. We show how this process can be executed in real time on a resource limited device known as the Game Boy Advance, and also illustrate a significant reduction in the memory requirements of terrain storage when compared with traditional methods

System support for client-server based interactive applications in ad hoc networks

With the emergence of wireless communications and mobile computing. new ways for people to interact with each other and their surrounding environment are emerging. Mobile devices, such as Personal Digital Assistants (PDAs) with wireless communication interfaces are able to communicate directly with each other if they are "close enough". If such devices are also able to act as message relays (routers), then a very powerful facility in the form of a mobile ad hoc network can be made available to applications. Although present day PDAs have sufficient networking and processing capabilities to support interesting interactive applications, as yet, there is hardly any software available for constructing and maintaining ad hoc networks and not many practical interactive applications have been built and tested. Rather, much of the research work is still at simulation and modelling stage. Thus it is difficult at this stage to decide what system support (middleware) for interactive applications a PDA should contain. This work is a step in the direction of remedying the situation by considering a class of applications where interactions between users can be supported by one of the nodes in the ad hoc network acting as a server. The thesis presents the design, implementation and evaluation of three such applications on PDAs, and based on that experience, describes what system support (middleware) for such applications is required. These applications are: Auction, Bingo game and Chatting that work over ad hoc networks. The work presented here can be used as a basis for deciding how the current generation of PDA operating systems can be extended for supporting ad hoc networking and what additional services are required for interactive applications.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Guidelines and infrastructure for the design and implementation of highly adaptive, context-aware, mobile, peer-to-peer systems

Through a thorough review of existing literature, and extensive study of two large ubicomp systems, problems are identified with current mobile design practices, infrastructures and a lack of required software. From these problems, a set of guidelines for the design of mobile, peer-to-peer, context-aware systems are derived. Four key items of software infrastructure that are desirable but currently unavailable for mobile systems are identified. Each of these items of software are subsequently implemented, and the thesis describes each one, and at least one system in which each was used and trialled. These four items of mobile software infrastructure are: An 802.11 wireless driver that is capable of automatically switching between ad hoc and infrastructure networks when appropriate, combined with a peer discovery mechanism that can be used to identify peers and the services running and available on them. A hybrid positioning system that combines GPS, 802.11 and GSM positioning techniques to deliver location information that is almost constantly available, and can collect further 802.11 and GSM node samples during normal use of the system. A distributed recommendation system that, in addition to providing standard recommendations, can determine the relevance of data stored on the mobile device. This information is used by the same system to prioritise data when exchanging information with peers and to determine data that may be culled when the system is low on storage space without greatly affecting overall system performance. An infrastructure for creating highly adaptive, context-aware mobile applications. The Domino infrastructure allows software functionality to be recommended, exchanged between peers, installed, and executed, at runtime