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
Oblique Mercator RL and GC
RL concave to poles
GC concave to DGC(datum great circle)
Oblique Mercator scale
Correct at DGC
Oblique Mercator convergency
Correct @ DGC
Oblique Mercator qualities
Orthomorphic
Non perspective
Oblique Mercator coverage
5deg above below DGC
Oblique Mercator light source and use
LS - centre
Use -TO FLY GC ROUTES
Lambert conical has
2 standard parallels
1 parallel of origin
Lambert conical RL and GC
RL- concave to poles
GC -concave to parallel of origin
Lambert conical scale
Correct at 2 standard parallels
Lambert conical convergency
Correct @ parallel of origin
Lambert qualities
Orthomorphic
Non perspective
Lambert conical coverage
10deg N/S to 70deg N/S
Lambert light source and use
Light source -centre
Use -countries with mid latitudes
Convergency formula (lambert)
Chlong x sin of parallel of origin
Constant of cone (n)
= sin of parallel of origin
Polar stereographic RL and GC ( har cheez poles)
RL- concave to poles
GC -concave to poles
Polar stereographic scale
Correct at poles
The only perspective chart
Polar stereographic
Polar stereographic qualities
Orthomorphic
Perspective
Convergency of polar stereographic
At poles
Coverage polar stereo
70deg N/S to 90deg N/S
Light source and use of polar stereographic
Light source - at opposite pole
Use -countries close to poles
Convergency formula polar stereo
Chlong x sin90deg
ALWAYS TAKE ANGLE AS 90deg in polar stereo
Scale (expressed in cm) is
Chart length/ Earth length Or/And Da/Db=cosA/cosB Where d= denominator A= lat or scale to be found B=lat or scale given
(KW)A perfectly straight line on a lambert chart is
Meridian of longitude
