Data structures for terrain modelling and ground cover data

Modern radio system planning methods require accurate information on the terrain over which the radio signals passes. This information includes terrain height, the nature of the terrain, vegetation type, and details of man made structures. The ideal resolution to which topographic data should be collected and stored is such that both the storage requirements and computing time necessary to process the data can be completely impractical, even assuming that sufficiently detailed data is available. Data models and structures for digital elevation data can be classified into topological models (regular, semi-regular and irregular) in which the elevations are structured into some specific order, taking into account their spatial relationships, and mathematical models (global or local, approximating or interpolating) in which the terrain is described by one or more mathematical functions. The authors describe the main models, illustrate some data structures of these types and compare their performance. Given a data structure that is efficient in all respects except space efficiency, it may be possible to mitigate the problem by a data compression technique