Map Projections Flashcards
What is map projection?
The process of transferring images from the 3D surface of the Earth or other round body onto a 2D plane.
What are non-conformal projections?
- Non-conformal projections are ways of projecting the globe onto 2D but cannot be used for navigation as they are only accurate scale for 1 particular point.
What are conformal projections?
- Any angles on earth are preserved on the projection. Distances over small areas are correct to a scale.
- Used for aeronautical navigation
What are the two types of conformal projections?
- Conic and cylindrical
What are Mercator projections? What are the three types?
- They are cylindrical projections
1) Normal
2) Oblique
3) Transverse
What are the characteristics of normal Mercator projections?
1) The meridians and parallels are drawn as straight lines at right angles
2) Scale is only correct along the equator
3) Meridians of longitude are equally spaced apart
4) Parallels of latitude increase in spacing towards the poles
5) Shapes are correct
6) The size of countries distorts toward the poles
What is the universal transverse Mercator coordinate system?
It is a way of dividing up the earth and is useful for Joint Operational Graphic and Topographical Charts.
What are rhumb lines and great circles represented on mercator projections?
1) Rhumb lines are straight lines
2) Great circle lines are curved lines
What are lambert projections?
They are a type of conical projections
What are rhumb lines and great circles represented on lambert projections?
1) Rhumb lines are curved lines
2) Great circle lines are straight lines
What are the properties of an ideal aeronautical chart?
1) True shape of all surface features
2) Angles on the chart should equate to angles on the earth
3) Scale should be constant such that distance measured anywhere is accurate anywhere on earth.
What is the WGS 84 Reference ?
This is the reference coordinate system used or GPS navigation
How is the WGS 84 Reference frame realized?
Through a number of ground based monitoring stations that enable corrections for tectonic plate drift.
Are all countries compliant with WGS 84?
No
Are web based applications compatible for aircraft?
No as they use non conformal projections
