1. A 3D modeling apparatus comprising: an accepting unit configured to accept a plurality of pairs of images that are obtained by capturing a subject at different angles using a stereo camera; a generator configured to generate a plurality of 3D models of the subject based on the pairs of images, wherein each of the 3D models corresponds to one of the pairs of images; a selector configured to select a first 3D model and a second 3D model from the plurality of 3D models, wherein the second 3D model is to be superimposed on the first 3D model; an extracting unit configured to extract a plurality of first feature points from the first 3D model and extract a plurality of second feature points from the second 3D model; an acquiring unit configured to acquire coordinate transformation parameters for transforming coordinates of the second 3D model into coordinates in a coordinate system of the first 3D model, based on the first and second feature points; a transformation unit configured to transform the coordinates of the second 3D model into coordinates in the coordinate system of the first 3D model, based on the coordinate transformation parameters; and a combining unit configured to superimpose the second 3D model having the transformed coordinates on the first 3D model.