1. A system for reconstructing a three-dimensional (3D) model, the system comprising: a low resolution reconstruction unit that comprises: a scale adjuster that converts a first depth map, acquired by scanning a scene with a depth camera, into a second depth map having a low resolution by downsizing the first depth map, a first map converter that converts depth data in the second depth map into point cloud data in a coordinate system in 3D space, a first sensor tracker that matches point cloud data in the second depth map with point cloud data in a previous second depth map by using an iterative closest point (ICP) algorithm and extracts pose change information about a pose change of the depth camera based on the result of matching, and a first volume constructor that integrates together point cloud data in the second depth map and the previous second depth map and generates, a low resolution 3D model in real-time, based on the pose change information of the depth camera; and a high resolution reconstruction unit that processes the first depth map by using the pose change information of the depth camera that is extracted from the second depth map and reconstructs a high resolution 3D model.