Pie slice sectoring algorithm for computer generated imagery

A graphics-database-sectoring algorithm has been developed and used to realize real-time computer-generated imagery for helicopter simulator outside-the-window visual displays. The main considerations in the development of the database were: frame rates high enough for smooth real-time animation, and high scene detail to achieve maximum realism. These two objectives are conflicting and tradeoffs are required. Maximum scene realism is achieved by using texturing, pop-up detail, shadows and fading of the sky. High frame speed is maintained by sectoring the database and displaying only the sectors in the direction of the pilot´s heading, with the near ones in high detail and those far away in low detail. The display of the sectors in the pilot´s field of view is done by dividing the database into 12 pie-shaped slices where the origin of the frame of reference of the pie slices is attached to the pilot and moves with him. Frame time is further reduced by accomplishing hidden surface removal using an indexing technique in which each object is displayed according to an assigned index number dependent on physical location in the database