Chapter 2 Flashcards

1
Q

Define ‘geodesy’

A

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

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2
Q

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

A

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

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3
Q

Define & explain ‘classic geodesy’

A

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

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4
Q

Define & explain ‘modern geodesy’

A

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

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5
Q

What is accuracy in GIS?

A

Ability to hit a target

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6
Q

What is precision in GIS?

A

Ability to repeat results

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7
Q

What is error in GIS?

A

The linear distance between represented data & reality

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8
Q

Define & explain ‘GNSS’

A

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!

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9
Q

Define ‘topographic surface’

A

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

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10
Q

How is the topographic surface defined?

A

Using landforms and relief.

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11
Q

What is relief in GIS?

A

Difference between highest and lowest point within a particular area.

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12
Q

What are landforms in GIS?

A

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

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13
Q

Define and explain ‘geoid’

A

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.

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14
Q

Explain why geoids are used in GIS & cartography

A

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

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15
Q

Define “ellipsoid”

A

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

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16
Q

Define “ellipse”

A

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]

17
Q

When is an ellipsoid a spheroid?

A

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

18
Q

Define “spheroid”

A

An ellipsoid with 2 of its 3 measurements equal

19
Q

Define “oblate spheroid”

A

A spheroid wider than it is tall

20
Q

Define “prolate spheroid”

A

A spheroid taller than it is wide

21
Q

What 3D shape best represents earth?

A

Oblate spheroid

22
Q

What is the “ellipsoid of revolution”?

A

Another name for a spheroid

23
Q

Define “reference ellipsoid”

A

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

24
Q

Define “global reference ellipsoid”

A

Reference ellipsoids that are drawn to best fit the entire geoid

25
Q

Define “local reference ellipsoid”

A

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