SGa map which shows all the roads, paths, hills etc of an area in detail 〔精细准确的〕地形测量图
Examples from the Corpus
Ordnance Survey map• Lorton paused to consult his Ordnance Survey map.• Filling a substantial amount of skyline and covering six full squares of the Ordnance Survey map.
OriginOrdnance Survey map
(1800-1900) Because the maps were originally made for the department responsible for ordnance: ordnance “military materials”((14-20 centuries)), from Old Frenchordenance