maps,projections,charts,scale Flashcards

1
Q

Types of projections and the charts derived from them

A

1) Cylindrical projection— Mercator chart
2) Conical projection—Lambert conformal chart
3) Azimuthal projection—Polar stereographic chart

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2
Q

Ideal projection qualities

A

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

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3
Q

Categories of projection

A

Non perspective -Mercator &lambert

Perspective- polar stereographic ONLY

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4
Q

Cylindrical projection planes

A

Vertical -Direct Mercator
Horizontal-Transverse Mercator
Diagonal- Oblique Mercator

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5
Q

Direct/standard Mercator RL and GC lines ?

A

RL-straight line

GC-concave to the equator

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6
Q

standard Mercator scale

A

Scale - correct at equator &expands @sec theta when moving away from Equator

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7
Q

In direct Mercator Earth convergency and Chart convergency at equator and away from equator?

A

EC=CC at equator (0)

EC>CC away from eq

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8
Q

Direct Mercator qualities

A

Orthomorphic

Non perspective

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9
Q

Direct Mercator chart coverage

A

70degrees NORTH/ SOUTH

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10
Q

Direct Mercator light source and use

A

Light source -centre

Use - countries CLOSE TO THE EQUATOR

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11
Q

Transverse Mercator RL and GC ?

A

RL-concave to poles

GC -concave to equator and datum meridian

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12
Q

Transverse Mercator scale ?

A

Scale - correct at datum meridian

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13
Q

Transverse Mercator EC,CC ie CONVERGENCY

A

convergency correct @ equator and poles

EC=CC @ poles and eq

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14
Q

Transverse Mercator qualities

A

Orthomorphic

Non perspective

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15
Q

Transverse Mercator coverage

A

5degrees E/W to datum meridian

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16
Q

Transverse Mercator light source and use

A

Light source- is at equator

Use - Countries with large N/S EXPANSIONS

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17
Q

Oblique Mercator RL and GC

A

RL concave to poles

GC concave to DGC(datum great circle)

18
Q

Oblique Mercator scale

A

Correct at DGC

19
Q

Oblique Mercator convergency

A

Correct @ DGC

20
Q

Oblique Mercator qualities

A

Orthomorphic

Non perspective

21
Q

Oblique Mercator coverage

A

5deg above below DGC

22
Q

Oblique Mercator light source and use

A

LS - centre

Use -TO FLY GC ROUTES

23
Q

Lambert conical has

A

2 standard parallels

1 parallel of origin

24
Q

Lambert conical RL and GC

A

RL- concave to poles

GC -concave to parallel of origin

25
Q

Lambert conical scale

A

Correct at 2 standard parallels

26
Q

Lambert conical convergency

A

Correct @ parallel of origin

27
Q

Lambert qualities

A

Orthomorphic

Non perspective

28
Q

Lambert conical coverage

A

10deg N/S to 70deg N/S

29
Q

Lambert light source and use

A

Light source -centre

Use -countries with mid latitudes

30
Q

Convergency formula (lambert)

A

Chlong x sin of parallel of origin

31
Q

Constant of cone (n)

A

= sin of parallel of origin

32
Q

Polar stereographic RL and GC ( har cheez poles)

A

RL- concave to poles

GC -concave to poles

33
Q

Polar stereographic scale

A

Correct at poles

34
Q

The only perspective chart

A

Polar stereographic

35
Q

Polar stereographic qualities

A

Orthomorphic

Perspective

36
Q

Convergency of polar stereographic

A

At poles

37
Q

Coverage polar stereo

A

70deg N/S to 90deg N/S

38
Q

Light source and use of polar stereographic

A

Light source - at opposite pole

Use -countries close to poles

39
Q

Convergency formula polar stereo

A

Chlong x sin90deg

ALWAYS TAKE ANGLE AS 90deg in polar stereo

40
Q

Scale (expressed in cm) is

A
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
41
Q

(KW)A perfectly straight line on a lambert chart is

A

Meridian of longitude