A realtime computer-based viewing system comprising a database of first software objects in registration with one another, wherein at least one of the first software objects corresponds to a physical structure which is to be viewed by the system and at least one of the first software objects corresponds to a graft which is to be deployed adjacent to the physical structure, an endoscope for acquiring data about the physical structure when the physical structure is located within the endoscope's data acquisition field, wherein the endoscope is capable of being moved about relative to the physical structure, generating apparatus for generating a second software object using data acquired by the endoscope, wherein the second software object corresponds to the physical structure currently being viewed by the endoscope, registration apparatus for positioning the second software object into the database in proper registration with the first software objects already contained in the database, and processing apparatus for generating an image from the software objects contained in the database, based upon a specified point of view.