Processes and systems are disclosed for determining attributes of a roof structure of real-world three-dimensional building(s), including providing computer input field(s) for a user to input location data generally corresponding to the location of the building, providing visual access to a nadir image of a region including the roof structure of the building; on the nadir image of the region, providing a visual marker that is moveable on the computer monitor around the region, the visual marker initially corresponding to the location data but which may be moved to a final location, having location coordinates, on top of the building to more precisely identify the location of the building roof structure; providing a computer input capable of signaling user-acceptance of the final location of the marker; and, providing visual access to one or more oblique images of an aerial imagery database corresponding to location coordinates of the final location.