A Distributed Visualisation Tool for Digital Terrain Models

Comet is an interactive visualisation tool, which supports real-time visualisation and exploration of very large Digital Terrain Models (DTMs) on commodity workstations. Comet is designed to be portable across a range of different hardware architectures and network environments, and has been implemented using a novel combination of standard software components. A tile-based Distributed Shared Memory (DSM) is used to maintain and distribute a large DTM across a number of different machines. The soft real-time performance requirements of an interactive application were a significant challenge, and have caused us to employ a range of optimisation techniques. In particular, a series of caching strategies is used in conjunction with multi-threading to maximise client rendering performance. This technical report outlines the design and structure of Comet, and discusses a number of implementation issues. It also presents a limited set of performance measurements, and some recommendations for future development.