Designation of district boundaries. The district boundary lines are intended generally to follow the center lines of streets, the center lines of railroad rights-of-way, existing lot lines, the center line of streams and other waterways, or Village boundary lines, all as shown on the Zoning Map; but, where a district boundary line does not follow such a line, its position is shown on said Zoning Map by a specific dimension expressing its distance in feet from a street center line or other boundary line as indicated. Where no dimensions are given, the Zoning Officer shall scale the dimensions.