1. A computer-readable storage medium having stored therein an overhead map resource generation program which is executed by a computer of an overhead map resource generation apparatus for generating a resource for displaying an overhead map corresponding to a virtual three-dimensional space, the overhead map resource generation program causing the computer to function as: shooting means for shooting an overhead image of a region in the virtual three-dimensional space with a virtual camera provided in the virtual three-dimensional space; determination means for determining whether or not information about a color included in the overhead image shot by the shooting means satisfies a predetermined condition; and resource data generation means for generating resource data by accumulating, in a predetermined storage medium, image data of the overhead image which the determination means determines does not satisfy the predetermined condition, and processing performed by the shooting means, the determination means, and the resource data generation means being repeated until all overhead images corresponding to a predetermined region in the virtual three-dimensional space are shot by the shooting means.