Latitudes and longitudes of first and second points on a measured map image are recorded together with an image file. First, a beginning of position information data of the map image is shown. Subsequently, it is shown that information of the first point is started. Subsequently, an X coordinate of the first point on the map image is shown. Subsequently, a Y coordinate of the first point on the map image is shown. Subsequently, the latitude of the first point is shown. Subsequently, the longitude of the first point is shown. Subsequently, it is shown that information of the second point is started. Subsequently, an X coordinate of the second point on the map image is shown. Subsequently, a Y coordinate of the second point on the map image is shown. Subsequently, the latitude of the second point is shown. Subsequently, the longitude of the second point is shown.