4. The three-dimensional model retrieval apparatus according to claim 1 , wherein said model describing unit generates an image descriptor for each of said two-dimensional images, and sets a collection of the image descriptors of all two-dimensional images as the model descriptor of the three-dimensional model.
4. The three-dimensional model retrieval apparatus according to claim 1 , wherein said model describing unit generates an image descriptor for each of said two-dimensional images, and sets a collection of the image descriptors of all two-dimensional images as the model descriptor of the three-dimensional model. 6. The three-dimensional model retrieval apparatus according to claim 4 , wherein said three-dimensional model retrieval apparatus takes a two-dimensional image as the query, and said retrieving unit calculates, based on the model descriptor of the three-dimensional model in the model database, a distance between the two-dimensional image serving as the query and the three-dimensional model in the model database to perform the retrieval based on the distance.