Desktop virtual reality in the assessment of tidal effect

This paper describes a system that builds desktop virtual reality models based on topographic maps, and an application to tidal dynamics analysis is shown. The virtual reality model allows the user to explore the scene from any possible point of view, also permitting one to alter the level of the sea simulating all possible tides. With each tide level, flooded and dry areas are visible and the flooding pattern can be observed. Tides can be simulated with the use of an interface that creates cyclic situations. The system allows the choice of texture and colors, the creation of routes and the placement of marking objects such as buoys etc. The application receives a (possibly irregular) digital elevation model, and builds a virtual reality description using the virtual reality modeling language, which allows good interaction between the user and the model. The application only requires a major Internet browser with a free plug-in. A case study is performed with synthetic aperture radar data acquired near the city of Bremerhaven, an intertidal zone along the German coast. This zone is temporarily flooded and it is separated into tidal flats that fall dry and tidal channels that remain filled with water during a tidal cycle. The topography over this area is usually flat over tenths of kilometers. Height variations depend on the distribution of the tidal inlets and the distribution of the sediments. Due to these currents and wave action the topography of these area is highly dynamic