maps,projections,charts,scale Flashcards
Types of projections and the charts derived from them
1) Cylindrical projection— Mercator chart
2) Conical projection—Lambert conformal chart
3) Azimuthal projection—Polar stereographic chart
Ideal projection qualities
1) Gc and RL lines -straight lines
2) orthomorphic(brg on chart=brg on earth)
3) correct shape
4) adjacent sheet- fit each other
5) scale -constant& correct
Categories of projection
Non perspective -Mercator &lambert
Perspective- polar stereographic ONLY
Cylindrical projection planes
Vertical -Direct Mercator
Horizontal-Transverse Mercator
Diagonal- Oblique Mercator
Direct/standard Mercator RL and GC lines ?
RL-straight line
GC-concave to the equator
standard Mercator scale
Scale - correct at equator &expands @sec theta when moving away from Equator
In direct Mercator Earth convergency and Chart convergency at equator and away from equator?
EC=CC at equator (0)
EC>CC away from eq
Direct Mercator qualities
Orthomorphic
Non perspective
Direct Mercator chart coverage
70degrees NORTH/ SOUTH
Direct Mercator light source and use
Light source -centre
Use - countries CLOSE TO THE EQUATOR
Transverse Mercator RL and GC ?
RL-concave to poles
GC -concave to equator and datum meridian
Transverse Mercator scale ?
Scale - correct at datum meridian
Transverse Mercator EC,CC ie CONVERGENCY
convergency correct @ equator and poles
EC=CC @ poles and eq
Transverse Mercator qualities
Orthomorphic
Non perspective
Transverse Mercator coverage
5degrees E/W to datum meridian
Transverse Mercator light source and use
Light source- is at equator
Use - Countries with large N/S EXPANSIONS