Lecture #2

Question 1

What shape is Earth?

Answer 1

Oblate

Question 2

What is Geodesy?

Answer 2

The study of the shape of the Earth

Question 3

What are ellipsoids?

Answer 3

A sphere that possess variable radius’ from the centre providing a better representation of a sphere

Question 4

What is a geoid and how are they captured?

Answer 4

The geoid is the shape of the earth using gravitational data

Question 5

What is mean sea level used to describe?

Answer 5

Describes the shape of the planet to refer to geodetic

Question 6

What is a datum?

Answer 6

A reference point in which position measurements are made from

Question 7

What is a geodetic datum?

Answer 7

A reference to use and determine the size and shape of the earth and coordinate system

Question 8

What is a geocentric datum?

Answer 8

When the centre mass of the earth is aligned to the centre of an ellipsoid

Question 9

What is a reginal datum?

Answer 9

When there is an offset between the geoid and ellipsoid

Question 10

What is a geocentric and regional frame of reference and what are both good at representing?

Answer 10

A geocentric F.O.R . is a good approximation for the geoid while the regional is best used in a regional context

Question 11

What is NAD27?

Answer 11

A regional datum used in 1866 based of a reference ellipsoid

Question 12

What is NAD83?

Answer 12

A geocentric datum based of a reference ellipsoid from 1980. GPS is based of NAD83 (WGS83)

Question 13

What is the problem with using the wrong datum?

Answer 13

The incorrect system will result in mapping errors

Question 14

Name two coordinate systems

Answer 14

Planar and Latitude/Longitude

Question 15

What are the disadvantages and advantages of using each coordinate system?

Answer 15

Planar is convenient but least accurate while Lat/Long is least convenient but most accurate

Question 16

What is the geographical grid?

Answer 16

The geographical grid is used to determine the location of things on a latitude (horizontal) and longitudinal (pole connecters) system

Question 17

What is the degree of longitude at the equator and how does this differ the closer you get to the equator?

Answer 17

A degree of longitude is 111km at the equator and it gets smaller as you go farther from the equator because they end up meeting at the poles

Question 18

How do you convert decimal coordinates to degrees, minutes and seconds?

Answer 18

If degree is 30.4545, you follow this equation
30 degrees = 30 degrees
(0.4545x60) = 27.27 = 27 minutes
(0.27x60) = 16.2 = 16 seconds

Question 19

Why might we use planar maps?

Answer 19

The angles are more simplistic and UTM uses planar

Question 20

What is UTM?

Answer 20

A way of dividing the earth into 60 longitudinal zones and 20 latitude zones

Question 21

How does UTM work

Answer 21

Each degree of longitude is 6 degrees wide and it covers the earths surface. You will encounter them in datums and projections

Question 22

What is a projection?

Answer 22

A transformation of earths surface into a flat surface where all meridians and parallels, human and physical features are transformed in the process

Question 23

What is the significance of map projections?

Answer 23

Distortion is inevitable, although the projection you use should distort the least important parts and amplify the focus