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Geodesy Basics for Kentucky GIS

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Geodesy Basics for Kentucky GIS

  1. 1. Ross Mackay Kentucky Geodetic Advisor Geodesy Basics for Kentucky GIS 2009 Kentucky Geospatial Summit Frankfort, Kentucky September 10, 2009
  2. 2. ellipsoid Datum
  3. 3. geoid Datum
  4. 4. <ul><li>Latitude </li></ul><ul><li>Longitude </li></ul><ul><li>Height </li></ul><ul><li>Scale </li></ul><ul><li>Gravity </li></ul><ul><li>Orientation </li></ul>National Spatial Reference System NSRS Geodesy layer and how these values change with time Datum
  5. 5. h Land Surface h = Ellipsoidal Height Ellipsoid Geoid model H H = “elevation” N = Geoid height H ≈ h - N Datum N ?
  6. 6. Passive Control
  7. 7. TRANSCONTINENTAL ARC OF TRIANGULATION http://www.holoscenes.com/cgi-bin/moin.cgi/TranscontinentalTriangulation Map courtesy of Jim Irwin
  8. 8. Datum KGRN (NSRS 2007) 863 Horizontal 2079 Vertical 10123
  9. 9. Active Control
  10. 10. National CORS Network 1381 National CORS September 1, 2009 CORS
  11. 11. <ul><li>Paducah, KYTA </li></ul><ul><li>Jackson, KYTJ </li></ul><ul><li>Morehead, KYMH </li></ul><ul><li>Cumberland, KYCB </li></ul><ul><li>Somerset, KYSC </li></ul><ul><li>Campbellsville, KYCB </li></ul><ul><li>Taylor Lake, Lou5 </li></ul><ul><li>Madisonville , KYTB </li></ul><ul><li>Bowling Green, KYTC </li></ul><ul><li>Elizabethtown, KYTD </li></ul><ul><li>Louisville, KYTE </li></ul><ul><li>Covington, KYTF </li></ul><ul><li>Lexington, KYTG </li></ul><ul><li>Somerset, KYTH </li></ul><ul><li>Flemingsburg, KYTI </li></ul><ul><li>Manchester, KYTK </li></ul><ul><li>Pikeville, KYTL </li></ul><ul><li>Greenbo Lake SRP, KYGB </li></ul><ul><li>Dale Hollow SRP, KYDH </li></ul><ul><li>Rough River SRP, KYRR </li></ul>CORS
  12. 12. Hyperactive Control
  13. 13. NSRS
  14. 14. NSRS
  15. 15. NAD 83 vs. ITRF00 2.2 meters NAD 83 origin ITRF 00 origin Earth’s Surface h 83 h 00 Identically shaped ellipsoids (GRS-80) a = 6,378,137.000 meters (semi-major axis) 1/f = 298.25722210088 (flattening) NSRS
  16. 16. NAVD 88 Referenced to Father’s Point NSRS
  17. 17. GRAV-D NGS 10-Year Plan NSRS
  18. 18. Ten-Year Milestones (2018) <ul><li>NGS will redefine the NSRS vertical datum based on GNSS and a gravimetric geoid. </li></ul><ul><li>NGS will redefine the NSRS horizontal datum, removing disagreement with the ITRF. </li></ul>NSRS
  19. 19. Predicted positional changes for datums in 2018 (Florida example) NSRS Horizontal = 0.82 m (2.7 ft) Ellipsoid Height = - 1.55 m (- 5.1 ft) Predicted with HTDP Orthometric Height = - 0.04 m (- 0.1 ft) Predicted with HTDP and USGG2009
  20. 20. Ross Mackay Kentucky Geodetic Advisor [email_address] on the web at ngs.ky.gov (502) 564-1474

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