EARTH - MAP RELATIONSHIPS

1. EARTH - MAP RELATIONSHIPS The Size and Shape of the Earth

3. EARTH - MAP RELATIONSHIPS The Size and Shape of the Earth

5. Globe

6. Flat Map

7. EARTH-MAP RELATIONSHIPS 1. Definition of Geodesy 2. Shapes of the Earth 3. Geographic Coordinates 4. The Graticule 5. Geodetic Control Points

8. EARTH-MAP RELATIONSHIPS 1. Definition of Geodesy 2. Shapes of the Earth 3. Geographic Coordinates 4. The Graticule 5. Geodetic Control Points

9. 1. GEODESY • The science concerned with determining the size and shape of the Earth • Establishment and maintenance of a global three-dimensional network of geodetic control points. • Measuring Geodynamic Phenomena (Geodynamics) • To Determine: • The exact positions of points on the earth’s surface • The size and shape of the earth • The variations in terrestrial gravity

10. EARTH-MAP RELATIONSHIPS 1. Definition of Geodesy 2. Shapes of the Earth 3. Geographic Coordinates 4. The Graticule 5. Geodetic Control Points

11. 2. THE SHAPES OF THE EARTH • SPHERE • ELLIPSE • ELLIPSOID • GEOID • GEOID SEPARATION

12. THE SHAPES OF THE EARTH • SPHERE: • A body of space bounded by one surface all points of which are equally distant from a point (center). • Constant radius

13. THE SHAPES OF THE EARTH • ELLIPSE: The path of a point the sum of whose distances from two fixed points (the foci) is constant

14. THE SHAPES OF THE EARTH • ELLIPSE: Flattening:

15. THE SHAPES OF THE EARTH • ELLIPSE: Flattening: World Geodetic System ‘84 WGS ‘84 a = 6,371,137 meters b = 6,356,752.2142 meters f = 298.25722

16. THE SHAPES OF THE EARTH • ELLIPSOID (SPHEROID): Surface developed by rotating an ellipse about its minor axis (oblate spheroid - tomato shaped) or major axis (prolate spheroid - cigar shaped).

17. THE SHAPES OF THE EARTH • ELLIPSOID (SPHEROID):

18. THE SHAPES OF THE EARTH • GEOID: The equipotential surface of the Earth’s gravity field which coincides with the surface the oceans would have if they were motionless and affected only by the Earth’s gravity field.

19. THE SHAPES OF THE EARTH • GEOID: An exaggerated view of the geoid in relation to the ellipsoid and the sphere

20. GEOID ‘96A view of the Continental US

21. GEOIDA view of the world

22. GEOID SEPARATION • GEOID SEPARATION: The perpendicular distance from the reference ellipsoid to the geoid. + The Geoid is above the Ellipsoid - The Geoid is below the Ellipsoid WGS ‘84 Ellipsoid and Geoid ‘96: Maximum separation worldwide  100 meters In Continental U.S.  - 20 meters

23. Geoid Height = Geoid Separation  Geoid Undulation

24. THREE EARTH SURFACES Geoid Height

25. GEOID SEPARATION

26. “The Four Corners of the Earth” 1 2 4 3

27. GEOID UNDULATION

28. Ellipsoid Datum Fit with Geoid

29. EARTH SURFACES

30. GEOID - ELLIPSOID RELATIONSHIP STATION “DURHAM 1943” : • Located behind Kendall Hall • Geoid Height (Geoid 93 Model) = - 27.184 meters •  10 cm (3’ by 3’ Lat., Long. Grid) ( 100 km) • Geoid ‘96:  3 cm (1) (2’ by 2’ Lat., Long.) • Geoid ‘99: • Elevation 106.46’ (above “mean sea level”)

31. GEOID - ELLIPSOID RELATIONSHIP STATION “DURHAM 1943” :

32. GEOID - ELLIPSOID RELATIONSHIP STATION “DURHAM 1943” :

33. GEOID - ELLIPSOID RELATIONSHIP

34. EARTH-MAP RELATIONSHIPS 1. Definition of Geodesy 2. Shapes of the Earth 3. Geographic Coordinates 4. The Graticule 5. Geodetic Control Points

36. 3. GEOGRAPHIC COORDINATES • LATITUDE:  • LONGITUDE: 

37. 3. GEOGRAPHIC COORDINATESLatitude and Longitude

38. 3. GEOGRAPHIC COORDINATES • LATITUDE:  The north-south position on the Globe “A Parallel”

39. 3. GEOGRAPHIC COORDINATES • LONGITUDE:  The east - west position on the Globe “AMeridian”

40. Orthogonal vs. Geographic Coordinates Ellipsoid Sphere Geographic Coordinates Orthogonal Coordinates “Authalic” Coordinates

41. 3a. GEODETIC COORDINATES • LATITUDE Angle formed by a line from the equator to the center of the earth, and a second line perpendicular to ellipsoid’s surface at your location. Point

42. 3a. GEODETIC COORDINATES • LONGITUDE Angle between a “prime” meridian and your “local” meridian. Point

43. REVIEW OF TOPICS EARTH-MAP RELATIONSHIPS 1.Definition of Geodesy 2. Shapes of the Earth 3. Geographic Coordinates 4. The Graticule 5. Geodetic Control Points

44. EARTH-MAP RELATIONSHIPS 1. Definition of Geodesy THE SCIENCE CONCERNED WITH DETERMINING THE SIZE AND SHAPE OF THE EARTH 2. Shapes of the Earth SPHERE, ELLIPSE, ELLIPSOID, GEOID, GEOID SEPARATION 3. Geographic Coordinates LATITUDE, LONGITUDE: GEOGRAPHIC (AUTHALIC) VS. GEODETIC, X,Y,Z