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What is the convergency factor on a Direct Mercator projection?
  • A
    0
  • B
    It varies as it is dependent on the latitude.
  • C
    The convergency factor is infinite.
  • D
    1

PROPERTIES OF A MERCATOR CHART  

Scale

Correct on the Equator.
Elsewhere increases as the secant of the latitude. Within 1% up to 8° from the Equator.

Orthomorphic

Yes. All charts used for navigation must be.

Graticule

Meridians are straight parallel lines, evenly spaced.
Parallels are straight parallel lines with the space between them increasing with the secant of the latitude.

Shapes

Reasonably correct over small areas.
Distortion over large areas, especially at high latitudes.

Chart Convergence

Zero everywhere. Correct at the Equator.
Constant across the chart.

Rhumb lines

Straight lines Always! Everywhere!

Great circles

Equator and meridians are straight lines (because they are also rhumb lines). All other great circles - curves, with a track nearer the Pole (or concave to the Equator).

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