Mapping the environment through three-dimensional space and time

Abstract

Traditional geographical information systems (GIS) employ a two-dimensional or at best 2.5-dimensional framework, suitable for many applications. However, mapping the environment introduces certain problems not easily managed within existing systems. The natural environment is constantly changing and this requires a more dynamic way of handling such data. Environmental media, such as the oceans and the atmosphere, complicate matters further as processes that occur within them vary through three-dimensional space and through time. In nearly all conventional GIS, time and depth have been handled as attributes to a geographical object (e.g. point, line, area). This can be very limiting, as there is no ready dimensional structure against which such objects can be displayed or manipulated relative to time and depth. This paper describes the Spatio-Temporal Environment Mapper (STEM), a GIS system that handles time or depth visualization of an entity in addition to mapping the entity horizontally. This treats time or depth as a dimension rather than an attribute, which is a prerequisite to effective multidimensional visualization and analysis. This is true three-dimensional data ( xy with a time or depth dimension) and is not to be confused with the modelling of three-dimensional solids. STEM has been developed for Land–Ocean Interaction Study (LOIS), a UK research project investigating forms and processes in the coastal zone. STEM is a GIS data viewer fronting a database containing the highlights of LOIS. STEM owes its flexibility to two key design objectives: a simple yet powerful query expression, retrieval and visualization interface and, secondly, a generic database design that provides the core of the data-driven system. The database represents the real world in terms of objects (‘features’) and properties (‘attributes’). Features and attributes can vary in both space and time.