An approach to the efficient rendering of terrain surfaces through the use of continuous level of detail but with maintenance of the integrity of added transportation features such as roads, bridges, railways, bus stops, and traffic lights is explored. A quadtree structure was developed to define the terrain surface as a gridded height field and, in the rendering process, to project transportation features in three dimensions onto the terrain surface on the fly. Also, with the viewpoint moving, the connected strips and fans between transportation features and terrain meshes were dynamically adjusted to reduce the projected pixel error. Consequently, the massive terrain and transportation features can be visualized simultaneously in an efficient way. This approach is illustrated with several snapshots, and the efficiency of the algorithms is also demonstrated.
Abstract