Coastline optimization and real-time rendering based on raster data sets

In 3D visual simulation because aerial photos and digital terrain elevation data always don´t match exactly, the coastline areas in the graphics generated by computer hardware are not always correct, especially in flight simulation where large-scale terrain scene is rendered. This paper proposes a new scheme to uniform coastline information between raster data sets. This method is base on coastline extraction, in which coastline is extracted from aerial photos to be applied as templates so that the difference of coastline position between aerial photo and digital elevation data can be forced to decay to zero. To make a better dynamic effect and to reduce the static visual error, a tidal modal is introduced to produce veridical intertidal zone. Coastline map is defined to hold coastline information which is pre-calculated. Also, ocean water was created with dynamic mesh, and depth-based transparency, caustics effects were produced for coastal waters. The performance of the method is verified through simulation.