Coordinate Systems

Question 1

What is the best model of the Earth?

Answer 1

A globe since it has the only true scale

Question 2

What are the Three types of Coordinate Systems?

Answer 2

• Rectangular (Cartesian)
• Geographic
• Astronomic

Question 3

What is the purpose of the Coordinate systems?

Answer 3

• simplify the earths surface
• surveying applications
• naviagtion

Question 4

Who created the rectangular coordinate system?

Answer 4

Rene Descartes

Question 5

What is Geographical Coordination

Answer 5

• Define position and Orientation, relative distance between two points
• Equator: formed by the intersection of a right angle to the axis of rotation
• Meridians: formed by vertical planes passing through the center. (0-180d)
• Parallels: 0-90d
• Latitude(n,s) and longitude(e,w) are points from the centre of the earth

Question 6

Where is the Prime Meridian Located?

Answer 6

Greenwich, England

Question 7

Astronomical Coordinates

Answer 7

• early form of mapping

- determined on a celestial sphere with Earth at the centre

Question 8

What is a Map Projection?

Answer 8

a method for mapping spatial patterns from a curved surface to a flat surface.

Question 9

What are some valuable properties of a map? (SADD)

Answer 9

• Shape
• Area
• Distance-(Scale of distances)
• Direction-(Compass Directions)

Question 10

What is Conformal?

Answer 10

When a map preserves shape over a small area. Means “right” in Greek

Question 11

What are three surfaces you can project a map on?

Answer 11

Plane, Cone and Cylinder

Question 12

On a plane projection map, what are three possibilities for the projection centre?

Answer 12

• Gnomonic (oldest map Projection)
• Stereographic
• Orthographic

Question 13

Gnomonic Projection:

Answer 13

-projection from centre of the earth onto the plane

• Great circles show up as straight lines
• (Will look like a compass)

Question 14

Stereographic Projection:

Answer 14

• Projection center opposite to the point of plane tangency. (projects through the earth onto a plane)
• (will look like a stretched bed sheet at the corners)

Question 15

Orthographic:

Answer 15

• Projection centre at infinity
• (projected from the edges of the earth)
• (will look like a circle with a straight line down the centre and curved lines radiating outwards)

Question 16

What are the two types of conical map projections? (light still projected from centre of earth)

Answer 16

• Secant (cone that passes through the edges of the earth)

- Tangent (cone that sits on top of the sphere, does not enter the surface)

Question 17

Tangent Conical Maps:

Answer 17

• STANDARD PARALLEL: to scale where the cone would touch the surface, distorts as you move away from this point.
• As the height of the cone increases, the standard parallel moves closer to equator
• When standard parallel reaches the equator it becomes a cone, when it hits the north pole it becomes a plane

Question 18

Secant (Lambert Conformal Conic):

Answer 18

• has 2 standard parallels since it passes through the surface of the globe that intersect at 1/6 of distance of top and south of map.
• Parallels: arcs of concentric circles with centre at apex
• Meridians: straight lines
• Scale true at both standard parallels

Question 19

Mercator Map Projection:

Answer 19

• will look like a stretched grid map, shows a constant bearing. These are called rhumb lines or loxodrome
• Meridians have equal spaced lines, while the parallels are horizontal lines whose spacing increases towards the poles

Question 20

Universal Transverse Mercator Map Projection (UTM):

Answer 20

• Similiar to the Mercator map but the projection is rotated 90d.
• looks like 4 ellipsoids, two from the poles and two from the equator.
• Can have one or two meridians with true scale
• projection zones are 6d wide

Question 21

What shape is the Earth?

Answer 21

An oblate ellipsoid and also a spheroid

Question 22

What Axis does the Earth rotate about?

Answer 22

Its short Axis (Minor Axis)