1. A real-time computer-based viewing system comprising: a database of pre-existing software objects, wherein at least one of said software objects corresponds to a physical structure which is to be viewed by said system and at least one of said software objects corresponds to a graft which is to be deployed adjacent said physical structure; a real-time sensor for acquiring data about said physical structure when said physical structure is located within that sensor's data acquisition field, wherein said sensor is capable of being moved about relative to said physical structure; generating means for generating a real-time software object corresponding to said physical structure using data acquired by said sensor; registration means for positioning said real-time software object in registration with said pre-existing software objects contained in said database; and processing means for generating an image from said software objects contained in said database, based upon a specified point of view.