1. An image processing apparatus comprising: one or more processors; and one or more memories storing instructions that, when executed by the one or more processors, cause the image processing apparatus to perform operations comprising: acquiring information for identifying a position of a vertex of a plane in a captured image, the captured image including a structure composed of a plurality of planes as an object; identifying points corresponding to positions of vertexes of the plane on a spherical coordinate that corresponds to an image-capturing range of an image-capturing unit that captures the captured image based on the information acquired by the acquiring; correcting positions of the points on the spherical coordinate to form a three-dimensional shape having the points on the spherical coordinate as the vertexes, into a predetermined three-dimensional shape; and generating an overhead image by making a region in the captured image corresponding to the positions of the points corrected by the correcting, as a region corresponding to the plane.