Chapter 2

Question 1

Define ‘geodesy’

Answer 1

Per NOAA, “the science of measuring and monitoring the size and shape of the earth & the location of points on its surface”

Question 2

Geodesy’ is “the science of ___ and ___ the ____ and ___ of the earth & the ___ of ____ on its ___”

Answer 2

“the science of measuring and monitoring the size and shape of the earth & the location of points on its surface”

Question 3

Define & explain ‘classic geodesy’

Answer 3

area of science concerned with: – length of day – measuring size of earth – geometry of earth – creating non-digital location/nav methods

Question 4

Define & explain ‘modern geodesy’

Answer 4

Helpful in studies of climate & environment + geohazards like quakes/tsunamis, the use of geodesy to monitor changes on earth such as: – surface deformation – crustal motion – polar motion – earth rotation – tides – the water cycle – sea levels – ocean circulation patterns – sea ice levels

Question 5

What is accuracy in GIS?

Answer 5

Ability to hit a target

Question 6

What is precision in GIS?

Answer 6

Ability to repeat results

Question 7

What is error in GIS?

Answer 7

The linear distance between represented data & reality

Question 8

Define & explain ‘GNSS’

Answer 8

General term for any system using locational satellites & triangulation to relearn the location of a receiver on the surface of earth. GPS is specifically the USA owner and operated version. It has 31 satellites. The more the better!

Question 9

Define ‘topographic surface’

Answer 9

The ‘real world.’ The surface we walk on daily. The actual place where we want to find and label points.

Question 10

How is the topographic surface defined?

Answer 10

Using landforms and relief.

Question 11

What is relief in GIS?

Answer 11

Difference between highest and lowest point within a particular area.

Question 12

What are landforms in GIS?

Answer 12

Descriptions of landscape features like mountains, valleys, & ridges.

Question 13

Define and explain ‘geoid’

Answer 13

A model of the variation between global mean sea level (GMSL) & local mean sea level (LMSL), based on graviry, used to measure precise elevations on the topographic surface. ALSO: A model of sea level to establish elevation values. ALSO: a model of gravitational acceleration across the earth. ALSO: a way to set zero elevation.

Question 14

Explain why geoids are used in GIS & cartography

Answer 14

To measure precise elevations on the topographic surface, via establishing a zero value for elevation of a feature

Question 15

Define “ellipsoid”

Answer 15

An ellipse with a 3rd dimension added (to make a “fat ellipse”)

Question 16

Define “ellipse”

Answer 16

A curved line forming a closed look where the sum of the distance between 2 points located on the major axis to every point on the line is constant. [IMG]

Question 17

When is an ellipsoid a spheroid?

Answer 17

When 2 of its 3 measurements are equal: “two/thirds of the way to a sphere”

Question 18

Define “spheroid”

Answer 18

An ellipsoid with 2 of its 3 measurements equal

Question 19

Define “oblate spheroid”

Answer 19

A spheroid wider than it is tall

Question 20

Define “prolate spheroid”

Answer 20

A spheroid taller than it is wide

Question 21

What 3D shape best represents earth?

Answer 21

Oblate spheroid

Question 22

What is the “ellipsoid of revolution”?

Answer 22

Another name for a spheroid

Question 23

Define “reference ellipsoid”

Answer 23

An ellipsoid that is drawn to best-fit an area. Global reference ellipsoids are drawn to best-fit the entire geoid; local reference ellipsoids are best fit on one side to a single place of the geoid

Question 24

Define “global reference ellipsoid”

Answer 24

Reference ellipsoids that are drawn to best fit the entire geoid

Question 25

Define “local reference ellipsoid”

Answer 25

Reference ellipsoids that are drawn to best fit on one side to a single place of the geoid