Basic Geodesy (Cartographic Fundamentals) Flashcards Preview

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Flashcards in Basic Geodesy (Cartographic Fundamentals) Deck (21)
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1

Geodesy

Science of Earth measurement

2

Pythagoras (6th Century B.C.)

Humans live on a perfect sphere

3

Aristotle (4th Century B.C.)

Sailing ships disappeared hull first and mast last..

4

Late 1600's

Conclusion : the Earth is not a perfect sphere, but rather a prolate spheroid

5

Issac Newton (1687)

Oblate spheroid

6

The Graticule (Geographic Grid)

Combination of latitude and longitude

7

Lines of Latitude (parallels)

Run east to west but are labeled north or south of the Equator

8

Lines of Longitude(Meridians)

Run North to South but are labeled east or west of the prime meridian

9

Reference Ellipsoid

a mathematically defined surface that approximates the geoid

10

Worldwide used Ellipsoids

Geodetic reference System (GRS)1980
World Geodetic System 1984 (WGS84)

11

Geoid model

Most precise shape of Earth, approximates mean sea level, is the shape that the surface of the oceans would take under the influence of Earth gravitation and rotation alone(no current, wind, tides, waves)

12

Datums

Defines the size and shape of the Earth(reference ellipsoid) and some tie point that fixes the ellipsoid on the surface of Earth or the the center of Earth
(A datum also describe the origin and orientation of the coordinate system used)

13

Horizontal datum

Specifies locations in terms of geodetic latitude and longitude computed from a reference ellipsoid

14

Vertical Datum

determines elevation regarding the mean sea level>relates to the geoid

15

NAD

North American Datum

16

NAD27

Clarke 1866 Ellipsoid
Tie point at Meades Ranch (KS)

17

NAD83

Geodetic Reference System GRS80
Tie point at the center of Earth

18

Geographic Coordinate System (GCS)

Defines the shape of the earth>3D of the earth
Datum, ellipsoid, angular units of measure, prime meridian

19

Projected coordinate systems(PCS)

Used to show the 3d Earth into 2D flat sheet using projection(Does not work without GCS)

20

State Place Coordinate System (SPC)

Each zone (usually referred by the name of the State) is assigned its own coordinate system and projection

21

Universal Tranverse Mercator (UTM) Coordinate System

60 six degree zones elongated in North/South direction