1. A computer-readable, non-transitory medium that stores therein a computer program for analyzing a panorama image that is created by processing a series of picture frames, the computer program making a computer execute: extracting a partial image to constitute a part of the panorama image, from one picture frame among the picture frames; calculating optical flows of the one picture frame from the one picture frame and an adjacent picture frame; associating each of the optical flows with each pixel in the partial image; calculating a distance from a camera to a subject appearing in the partial image based on the associated optical flows; identifying the subject based on a distance pattern corresponding to the calculated distance; inputting a route of a mobile object on which a camera to obtain the series of the picture frames is mounted; and correcting the input route based on a result of identification at the identifying.