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 related to the building model and 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, with each other.