A generation method is disclosed. Two-dimensional (2D) images that are generated by photographing a space from different viewpoints with at least one camera are obtained. Resolutions of the 2D images are reduced to generate first images, respectively. Second images are generated from the 2D images, respectively such that a resolution of each of the second images is higher than a resolution of any one of the first images. First three-dimensional (3D) points are generated based on the first images. The first 3D points indicate respective first positions in the space. A second 3D point is generated based on the second images. The second 3D point indicates a second position in the space. A 3D model of the space is generated based on the first 3D points and the second 3D point.