SUBCOURSE EDITION - Modern Prepper

(1) For all large and medium scale mapping between the latitudes of 84°N and 80°S, theTransverse Mercator Projection is used. Beyond those parallels, the Polar Stereographic Projection isused.(2) For standard small-scale maps, the Lambert Conformal Conic Projection is used between84°N and 80°S; the Polar Stereographic Projection is used beyond those parallels.the map.(3) The projections used on special purpose small-scale maps vary to suit the requirements of(4) In the few areas of the world where British grids are still used, the projections specifiedfor them in TM 5-241-1 apply. British grids, however, are being gradually replaced by the UTM gridthroughout the world, and maps of these areas will be based on the standard projections listed inparagraph a above.b. The characteristics of the three principal projections used for military mapping are describedand illustrated in TM 5-241-1. A brief summary of these characteristics is given in the followingparagraphs.(1) Transverse Mercator Projection. Although mathematically derived, this projection may bevisualized as a cylindrical projection, but with the axis of the cylinder perpendicular to the polar axis ofthe earth instead of coincident with it, as in most cylindrical projections. The cylinder is tangent to theearth along a selected meridian; the scale of the projection is true along this meridian, with distortionincreasing east and west of the meridian. Thus, the Transverse Mercator Projection is most accurate formaps of areas of greater north-south extent, but with relatively narrow east-west proportions. Thischaracteristic has been exploited in the application of the projection to medium and large-scale militarymapping, by employing a series of 60 cylinders with each cylinder secant instead of tangent to thespheroid. Each cylinder (or zone) in turn is 60 wide, and each with its own central meridian. As aresult of this modification, scale distortions are minimized. The Universal Transverse Mercator Grid,paragraph 4-5, is developed from this system of 60 secant cylinders.(2) Polar Stereographic Projection. The Polar Stereographic Projection is developed on aplane surface tangent at either pole, with the projection rays originating at the opposite pole. Themeridians appear as straight lines radiating from the pole, while the parallels are concentric circles whosespacing increases with the distance from the pole. In its military application, the plane is made secant atapproximately 81° 07', thus minimizing scale distortion.128