To provide a virtual map generating method in an optional size by stacking graphic images and piecing together virtual map fragments.

A virtual map generator is configured to establish a plurality of basic landform graphic data blocks each representing a graphic image of a corresponding landform layer and to select at least two of the basic landform graphic data blocks. The virtual map generator is also configured to make virtual map fragments. The virtual map generator is configured to stack the graphic images corresponding to the selected basic landform graphic data blocks and to send a plurality of virtual map fragments to an electronic device via a network. The electronic device is configured to form a virtual map by piecing together the virtual map fragments, received from the virtual map generator.