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Polar Stereographic Projection Azimuthal Projections Azimuthal projections are obtained by projection on a horizontal or flat sheet of paper Since the paper is kept flat the projection forms a circular chart The reduced earth touches the paper at the pole called point of tangency Scale is correct only at the pole and expands away from the poles Scale Expansion of Azimuthal Projections Scale expansion is constant in all directions making the projection orthomorphic Latitudes are concentric circles and longitudes are radial straight lines from the poles Meridians and parallels intersect…

Lamberts Projection Lamberts Modification Lamberts is a non-perspective, orthomorphic, modified conical projection Lamberts modified the simple conic mathematically to make the cone go inside the reduced earth The parallel of origin is hence inside the reduced earth The parallels where the cone touches reduced earth are called its standard parallels Lambert modified the simple conic projection to make it usable for more latitudes Scale distortion was to limited to less than 1% for more greater latitude coverage Lambert’s Standard Parallels Standard parallels are latitudes where cone touches reduced earth Lamberts…

Conical Projections Introduction to Conical Projections Conical projections are made by wrapping the paper in a conical shape When the cone is cut open the projection is a circle with a sector missing Parallel of tangency is the latitude where the cone touches reduced earth Scale is correct only at the parallel of tangency and expands rapidly at higher as well as lower latitudes Scale expansion in all directions around a point is same and hence the projection is orthomorphic or conformal Latitudes are concentric arcs and longitudes are radial…

Oblique Mercator Introduction to Oblique Mercator Oblique Mercator is useful for flying specified great circle routes A datum great circle called false equator is taken as the parallel of tangency Scale is within 1% error up to 480 NM on either side of the Datum Great Circle Scale expansion is constantly equal to the secant of distance from datum great circle The projection is orthomorphic since the scale expansion same in all directions and Meridians and parallels cut at right angles Properties of Oblique Mercator Meridians and parallels are complex…

Transverse Mercator Introduction to Transverse Mercator Transverse Mercator is useful for mapping countries or air-routes with large north-south extent Unlike Normal Mercator, a meridian is selected as the parallel of tangency Scale of Transverse Mercator is correct in a vertical band of 480 NM either side of the datum meridian Scale expansion in all directions is proportional to secant of angular distance from datum meridian Transverse Mercator is orthomorphic projection, since it meets the two requirements for orthomorphism Scale expansion same in all directions around a point and meridians and…

Normal Mercator Projection Introduction to Mercator Cylindrical Projection Mercator modification equalised the North-South and East-West scale expansion making it orthomorphic Scale expansion of a Mercator chart in the the North-South and East-West is proportional to secant latitude Scale at Any Latitude = Scale (Equator) x Secant Latitude Mercator is a Non-Perspective Orthomorphic Cylindrical projection Scale Expansion and Orthomorphism of Mercator Charts Large Areas and High Latitudes distorts shape of natural features in a Mercator Chart Chart convergence is zero everywhere making it correct only at equator but constant throughout the…