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Cylindrical Projections Introduction to Cylindrical Projections Cylindrical Projections are made by wrapping paper in Cylindrical Shape around the Reduced Earth Paper touches reduced earth at the equator in a normal cylindrical projection Equator is the parallel of tangency or origin since the paper touches the reduced earth at the Equator Scale is correct only at equator since light travels correct length at equator Scale of Cylindrical Projections Scale of all perspective projections is correct at its parallel of tangency Scale is correct at the equator since it is the parallel…

Projections Introduction to Projections Projections are used to make maps and charts by projecting spherical (3D) earth on a paper (2D) Traditionally, map preparation was done in three steps Step 1 – A 3D transparent model of earth with latitudes and longitudes called reduced earth is made to scale Step 2 – Light is projected from inside the reduced earth on a wrapped photographic paper Step 3 – The wrapped paper is then cut opened to show latitudes and longitude Perspective projections are obtained by projecting light and are used…

Departure Departure Distance between two Meridians Departure is the distance between two meridians at a given parallel of latitude One minute of latitude would be one nautical mile along the equator and all meridians The rule does not apply to distances between meridians at other latitudes Distance between meridians is maximum at equator and reduces to zero at the poles Departure follows a cosine curve of latitude Parallels of latitude are rhumb lines hence it is a rhumb line distance Rhumb lines do not represent the shortest distance between two…