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GEOG 222 > GEOMATICS > Flashcards

GEOMATICS Flashcards

1
Q

What is Geomatics?

A

Geomatics is the modern scientific term referring to the integrated approach of measurement, storage and display of the descriptions and location of Earth-based data, often termed spatial data.

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2
Q

Earth-based data, of termed spatial data

A
  • space / place

* almost everything around us can be referred to as spatial

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3
Q

Spatial Data

A

Directly or indirectly referenced to a location on the surface of the earth

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4
Q

Non-spatial Data

A

Cannot be related to a location on the surface of the earth is referred as non spatial data

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5
Q

Geomatics combines of three elements

A
  1. geography
  2. mathematics
  3. computer science
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6
Q

Principal subject area comprising Geomatics

A
  • surveying and mapping
  • geodesy and gravimetry
  • land information management
  • positioning and navigation (GPS, GLONASS etc.)
  • Cartography + digital mapping
  • remote sensing (aerial, satellite, ground based)
  • photogrammetry
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7
Q

Where does spatial data come from?

A

This data comes form many sources, including earth orbiting satellites, air and sea-borne sensors and ground based instruments.
GITECHNOLOGIES

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8
Q

Spatial Data - how to manage/use those?

A

It is processed and manipulated with state-of-the-art information technology using computer software and hardware

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9
Q

Application of Geomatics?

A

It has applications in all disciplines which depend on spatial data

  • environmental studies
  • planning
  • engineering
  • navigation
  • geology & geophysics
  • oceanography
  • land development and land ownership
  • tourism
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10
Q

Canadian Resource Sectors Using Geomatics

A

-agriculture
-energy
-mining
-environmental protection and management
-land use planning, development & management
-water resource management
-forestry
-oceans and fisheries
health care
location based services
asset management
recreation and tourism
utilities
emergency planning and management

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11
Q

Value of GIS

A
  • providing access to context
  • spatial analysis
  • spatial modeling
  • spatial prediction
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12
Q

Spatial Analysis

A

using techniques to reveal what is not otherwise visible

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13
Q

Spatial modeling

A

simulating the action of landscape modifying processes

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14
Q

Spatial Prediction

A

forecasting where as well as when

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15
Q

Geospatial technology

A

the sciences, humanities, the general public

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16
Q

GIS is no longer all-encompassing

A

the 4th edition of Longley et al focuses on GI not GIS

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17
Q

Geography as a discipline

A

the principles thast make spatial special
the value of a spatial perspective
the importance of integrating data across layers, disciplines
the importance of ground truth

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18
Q

Geodesy definition

A

A scientific discipline the shape, size, rotation and gravity field of planet Earth including their variations in time

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19
Q

Geodesy important because…

A

surveying, mapping and navigation, remote sensing, mineral exploration, flood risk determination, transportation, land use, ecosystem management

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20
Q

Where does the word Geodesy comes from

A

-derived from the Greek for ‘earth’ and ‘I divide and measure’ and refers back to ancient Egyptian land surveying techniques

21
Q

Ancient measurement of Earth

A
  • plato determined the circumference of the earth to be 40, 000 miles
  • Archimedes estimated 30, 000 miles
  • Eratosthenes made more explicit measurements, 25, 000 miles
  • currently accepted circumference is 24, 901
22
Q

Physical concepts of Geodesy

A

Earth motions, relationship in solar system, plate tectonics, and gravity

23
Q

knowledge sources in geodesy

A

specialized application of several familiar facets of basic mathematics

  • measurements/survey/expeditions
  • modern technologies
24
Q

key terms in geodesy

A
  • datum (circle to sphere, ellipse to ellipsoid / spheroid, geoid)
  • coordinates system
  • projections
25
Q

basic geometry for geodesy

A
  • ellipse -> ellipsoid –> sphere
  • when the revolving oval is a perfect ellipse, the solid generated by the revolution is called the ellipsoid / (Spheroid)
26
Q

defining a spheroid

A

-a spheroid is defined by either the semimajor axis, a, and the semiminor axis, b, or by ‘a’ and the flattening.

27
Q

how is the flattening f derived

A

f = (a-b) / a

  • flattening is a small value, so usually the quantity 1/f is used instead
  • flattening ranges from 0 to 1. a flattening value of 0 means the two axes are equal, resulting in a sphere.
28
Q

what is datum

A

a reference point, surface, or axis on an object against which measurements are made

29
Q

geodetic datum

A

a reference from which spatial measurements are made

30
Q

spheroid of geodetic reference

A

-a spheroid or ellipsoid approx. the shape of the earth, a datum defines the position of the spheroid relative tot he center of the earth

31
Q

older ellipsoids

A

are named for the individual who derives them and the year of development is given

32
Q

international ellipsoid

A

developed by Hayford in 1910 and adopted by the international Union of Geodesy and Geophysics

33
Q

a unified geodetic system for the whole world became essential bcuz

A
  • advancement of space science and astronautics
  • lack if inter-continental geodetic information
  • need for global maps for navigation, aviation and geography and basis for a worldwide geo-data
34
Q

what adopted the GRS80

A

international association of Geodesy (IAG) in 1979

35
Q

what does a datum define

A

how a coordinate system is seated over the ellipsoid / spheroid

36
Q

what is the centre mass of the earth

A

NAD83 system and uses the GRS80 ellipse

37
Q

what is a geoid

A

a hypothetical earth surface representing the mean sea level in the absence of winds, current, and most tides

  • the arithmetic mean of hourly water elevations observations over a specific 19-year cycle and defined as the zero elevation for a local area
  • geodesists once believed that the sea was in balance with the earth gravity and formed a perfectly regular figure
38
Q

earths actual gravity field

A

the earths gravity field differs from the gravity field of a uniform, featureless earth surface
ex. Zero elevation as defined by Spain is not the same zero elevation defined by Canada, which is why locally defined vertical Datums differ from each other.

39
Q

can a geoid surface be directly observed

A

no heights above or below the geoid surface can’t be directly measured

40
Q

how are geoid measured

A

inferred by making gravity measurements and modeling the surface
-Geoid is the equipotential surface of the Earth’s gravity field which best fits, in a least squares sense, global mean sea level- NASA

41
Q

Geoid – Ellipsoid Relationships

A

The angle between a plumb line (perpendicular to the geoid) and the Normal line (the perpendicular to the ellipsoid) is called as the “deflection of the vertical”

42
Q

new Canadian geodetic vertical datum

A

The Canadian Geodetic Vertical Datum of 2013 (CGVD2013) was officially released in November 2013 representing by convention the coastal mean sea level for North America.
It replaces the Canadian Geodetic Vertical Datum of 1928 (CGVD28).

43
Q

what is CGVD28

A

a tidal Datum defined by the mean water level at five tide gauges: Yarmouth and Halifax on the Atlantic Ocean, Pointe-au-Père on the St-Lawrence River, and Vancouver and Prince-Rupert on the Pacific Ocean.

44
Q

horizontal datum

A

used for describing a point on the earth’s surface, in latitude and longitude or another coordinate system.

45
Q

vertical datum

A

used to measure elevations or depths.
-These are either based on sea levels or geoid and use the same ellipsoid models of the earth used for computing horizontal Datum

46
Q

geometric datum

A

records both of above and the UTC (coordinated universal time)

47
Q

what will a change in datum cause

A

a shift in every position the map

48
Q

adjoining sheets may be in different Datum causing

A

a loss or addition of detail at the map’s neat-line

49
Q

when using topo maps with adjoining sheets or with a GPS receiver you should always check..

A

the datum note first

GEOG 222 (5 decks)

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