Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

GEOG 222 > Coordinate System and Projection System > Flashcards

Coordinate System and Projection System Flashcards

1
Q

coordinate systems

A

a system which uses one or more numbers to uniquely determine the position of a point or other element within a space

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

properties that define a coordinate system

A

definition of axis: number, name, order/sequence

definition of measurements: unit, direction (positive/negative)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

3 kinds of coordinate systems

A

observer based - azimuth and altitude
earth based - latitude and longitude
celestial - declination and right ascension

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

earths rotation

A

counter clockwise

  • provides an axis connecting north and south poles
  • provides the basis for a system to determine location
  • geographic coordinate systems or geographic grid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

one rotation takes

A

a solar day (24hrs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

parallels define

A

degrees latitude relative to the equator

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

meridians define

A

define degrees longitude relative to prime meridian

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

network of lines

A
  • east-west (parallels)

- north-south (meridians)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

construction of parallels

A

Starting point is the axis of rotation
Equatorial plane
Imaginary plane through center of the earth
Perpendicular to the axis of rotation
Latitude
The angular distance towards north or south of the equator from the equatorial plane
00 at the equator and +900 at the North pole and -900 at the South pole

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

concept of small circles

A

circles produced by a plane passing through a sphere anywhere except its center are referred to as small circles
all parallels except the equator are small circles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

concept of great circles

A

if a sphere is divided exactly in half by a plane passing through its centre, the intersection of the plane with the sphere represents the largest circle that can be drawn on the sphere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

properties of great circles

A
  1. great circles are the largest circles that can be drawn on a spherical surface
  2. an infinite number of great circles can be drawn on a sphere
  3. Only one great circle can be drawn to pass through two points on the surface of a sphere – unless
    the two points are the ends of the same diameter
  4. An arc of a great circle is the shortest distance of two points on the surface of a spheroid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Construction of meridians

A 
Construction of meridians
Meridians are halves of great circles
Extend from north pole to south pole
No convenient place to start
Arbitrary starting point 
Meridian passing through Greenwich, England is the 0 meridian or prime meridian
Longitude
Angle between prime meridian plane and the meridian plane from the point of interest.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

longitude is expressed in

A 
degrees, minutes and seconds 
Indicate east-west position
West of prime meridian: W
East of prime meridian: E
Prime meridian 0o
Meridians are between 0o -180o
Western hemisphere
Eastern hemisphere
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

shortest distance between two points always

A

lies on a great circle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

distance from the lat/long

A 
Along the meridian (north-south) 
	= Earth’s Circumference/360	= 111 Km (approx.)
Along the parallel (east-west)
	= depends of the latitude
	= cos(latitude in degree) * (111)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what is projection

A

is a method of transferring features of the spherical Earth to a flat surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

map projections define

A

the spatial relationship between locations on earth and their relative locations on a flat map

19
Q

methods of projection

A

A method of projection provides an orderly system of parallels and meridian that is used to model the relative location of earth surface features on a two dimensional media.

i. e., mathematica system - Robinson projection, mollweide projection
i. e., geometric - lambert conformal conic, north pole azimuthal equidistan projection
i. e., Mercator projecting

20
Q

conceptual model of deriving map projections

A
  1. a transparent globe with geographical grid and may be continents are drown on it
  2. a light source placed inner side (center…) of the globe
  3. a paper placed on the surface of the globe in flat or conical or cylindrical shape
21
Q

why different types in conic, planar and cylindrical projection systems

A

Mapmakers and mathematicians have devised almost limitless ways to project the image of the globe onto papers to serve various purposes 
For Navigation (Mercator)
To show different parts of the world more accurately
To show world map more accurately
To show distribution patterns (Robinson)
For Administration………
ArcGIS supports 66 different types of map projections

22
Q

Which projection is the best?

A

No matter how we model our Earth, as spheroid, or on a two-dimensional flat surface, - each a less accurate than the preceding shape.
Every projection has its own set of advantages and disadvantages.
There is no “the best” projection.

23
Q

Spatial properties of earth surface features

A

No single projection can preserve, simultaneously, all of the main spatial properties –
angle, direction, distance, shape, area
On a map, the direction is correct means the bearing between two points is correct on anywhere on the map
If a projection preserves shape and area on the map, an area is uniformly proportional to the real world that they represent.

24
Q

Conformal Projection

A

– preserves the correct shapes of small areas.

25
Q

Equal Area Projection

A
  • quadrilaterals formed by meridians and parallels have an area on the map proportional to their area on the globe.
26
Q

Equidistant Projection

A
  • distance from a single location to all other locations are preserved.
27
Q

Azimuthal Projection

A

– directions from a single location to all other locations are preserved

28
Q

Compromise Projection

A

attempt to balance between the above characteristics, and is often used in thematic mapping.

29
Q

popular map projections

A

Mercator (Cylindrical)
Lambert conical conformal (Conical)
Transvers Mercator (transvers Cylindrical)

30
Q

Some projections cannot be expressed geometrically, have only mathematical descriptions

A

Goodes
Robinson
Molleweide
Eckert

31
Q

Gerardus Mercator Projection

A

a cylindrical projection with rectangulargrid
Distance between parallel increase with latitude
Polar cut-of at 800 N and 800 S
High distortion of shape and area toward pole,e.g.: Greenland shows same size as Africa
Scale on 600 latitude is 2 times (on 800, it 6X)of that on the equator
Impotent properties preserves direction (bearing), which makes it Indispensable for navigation
Other uses  to show linier features like wind flow line, ocean currents, global temperature and pressure patterns

32
Q

Polar Projection

A

Can be centred on either the North or South Pole
Meridians are straight lines radiating outward from the pole
Parallels are nested circles centred on the pole
Parallels with the meridians intersect at right angles
The space between the parallels increases outward from the centre
shows the true shapes of small areas,such as islands
Scale increases away from the centre
shapes look disproportionately larger toward the edge of the map

33
Q

Goodes Projection

A

Uses two sets of mathematical curves to form its meridians

Between the 40th parallels, it uses sine curves

Beyond the 40th parallel, towards the poles, it uses ellipses

Ellipses converge to meet at the pole, so the entire globe can be shown

Commonly used to show regional distributions of geographical features such as socials and vegetation.

Shows area in correct proportion.

It distorts the shapes of areas, particularly in high latitudes.

34
Q

Why is projection necessary?

A

Data often comes in geographic, or spherical coordinates (latitude and longitude) and cant be used for area calculations in most GIS software applications

35
Q

Angular Parameters

A

Central meridian or longitude of origin

Latitude of origin or central parallel

Longitude of center

Latitude of center

Standard Parallel

36
Q

Linear Parameters

A

False easting

False northing

Scale factor

37
Q

How to choose projections

A

Follow the lead of people who make maps of the area you are interested in.

For a map of Canada Lambert Conical Conformal projection is commonly used.

State plane is a common projection for all states in the USA.

UTM is commonly used and is a good choice hen the east-west width of area does not exceed degrees.

38
Q

Commonly used Datum Systems in Canada

A

WGS84 (World Geodetic System of 1984) - geodetic coordinate reference system (datum) developed and used by GPS. No physical monuments.

NAD83 (North American Datum of 1983) - developed based on GRS 1980.
The ellipsoid defined through the use of satellites.

Tied to the North American tectonic plate, meaning over time it diverges from WGS84.

NAD27 (North American Datum of 1927)-developed based on the Clarke Ellipsoid of 1866.
Discontinued from use but there are still use.
It coordinate difference from NAD83 depends on the location
~20 m around Thunder Bay.

39
Q

Transverse Mercator

A

Whole Earth can be shown, but all distances, direction, shapes, and areas are reasonably accurate within 15 degrees of the central meridian.

Distances are true only along the central meridian selected by the mapmaker or else along two lines parallel to it

This is an ellipsoid cylindrical projection that divides the world into numbered zones in longitude.

20 latitudinal zones from 80 degrees south to 84 degrees north denoted by letters C to X, omitting the letters I & O.

Each zone is 8 ^^0 south-north (except the “X” is 12 degrees)

Areas are referenced by quoting the longitudinal zone number, followed by the latitudinal zone letter.

40
Q

UTM Coordinates - Northern Hemisphere

A

UTM projection use easting and northing in metres for coordinates.

The central meridian’s coordinate is always 500,000

The Equators coordinate is designated 0 for quadrangles in the Northern Hemisphere

41
Q

UTM Coordinates - Southern Hemisphere

A

The central meridian’s coordinate is always 500,000

The equator’s coordinate is designated 10,000,000 for quadrangles in the southern hemisphere

42
Q

UTM Accuracy

A

Each zone is separately projected using the ellipsoidal form of the transverse Mercator projection with a secant case:
- scale of the central meridian is reduced by 0.04% so two lines about 1 degree 37” east and west of it have true scale

The UTM grid was designed for large-scale topographic mapping in separate sheet, not for world or regional maps

43
Q

Earth Orbital Revolution

A

An elliptical path around the Sun

Earth-Sun distance varies between aphelion and perihelion points

23.5 degrees with the ecliptic plane

44
Q

Celestial Coordinate System

A

North & South celestial pole - point in sky directly about north/south pole on Earth

Celestial Equator - circle surrounding earth

Ecliptic - a path followed by the sun through the sky over the course of the year.

Declination - angle from celestial equator (0^^0), positive UP, negative going DOWN

Celestial Prime Meridian - point where sun is located
at the vernal equinox (Spring)

Right Ascension (RA) - angle (degree) form the celestial “Prime Meridian” (equivalent of celestial longitude)

GEOG 222 (5 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions