1. A three-dimensional (3D) urban modeling apparatus, comprising: a calibration unit for calibrating data about a translation and a rotation of at least one capturing device at a time that input aerial images and terrestrial images were captured; a building model generation unit for generating at least one 3D building model based on the aerial images and the terrestrial images to which results of the calibration by the calibration unit have been applied; a terrain model generation unit for generating a 3D terrain model by converting an input digital elevation model into a 3D mesh; a texture extraction unit for extracting textures of buildings projected orthogonally from each face constituting the building model and textures of terrain related to the terrain model from the aerial images and the terrestrial images; and a model matching unit for generating a 3D urban model by matching the building model with the terrain model, which are based on the textures of buildings and terrain, with each other.