US Patent 7187377 Three-dimensional virtual tour method and system

A method and system that archive a three-dimensional site in a highly-compact manner such that real-time, three-dimensional exploration and interaction with the site with high-resolution graphics is enabled. During authoring, information is collected about a site, and processed into a walkmap comprising a number of maps. A visibility map indicates which ones of the many polygons that make up a site are potentially visible from a given region. A collision map establishes where a can navigate in the site. A ground map tracks the terrain for reproducing camera heights and viewing angles, and a trigger map causes scripts to be fired from locations in the site. During navigation, only the maps relevant to a user's current position are active, whereby rapid rendering of an appropriate image for the user's current perspective is possible in real-time, providing a first person, perspective tour of the site in a perceived three-dimensional environment.