1. Dr. A‘kif Al_fugara Alalbayt Univerity
Principles of Geodesy
Introduction
Dr. A‘kif Al_fugara
Alalbayt Univerity

2. Introduction What is Geomatics?
Geomatics Engineering is a rapidly developing discipline that focuses on spatial information
Geomatics Engineering includes the disciplines of:
geodesy and geodetic science,
photogrammetry
remote sensing,
mapping,
land and geographic information systems,
spatial computing, computer vision and
all types of surveying.
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

3. What is geodesy? From Greek: “ Dividing the Earth ”.
Geodesy is the branch of applied mathematics concerned with the determination of the size and shape of the Earth, with the exact positions of points on its surface, and with the description of variations of its gravity field.
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

4. Geodesy is answering these questions.
What does this means?
How big is the Earth?
Geodesy is answering these questions.
Which is the shape of the planet?
Where am I?
How far am I from a place?
How tall is a mountain?
Where my property ends?
How big is my property?
In which direction should I go?
Dr. A'kif Al_Fugara, Dept. of Surveying, AABU

5. Introduction Tasks of Geodesy- Determination of: To perform
Size and shape of the Earth
External gravity field of the Earth and other celestial bodies
Earth Rotation
Temporal variations in the shape, rotation and gravity field
To perform
geodetic measurements and
computations
That lead to determination of the coordinates of control stations on the Earth surface.
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

6. Introduction This course: Spherical Earth: Gravity field:
Basic spherical geometry
Spherical coordinates and computations
Gravity field:
Gravity field and potential
Astronomic coordinates
Geoid and level surfaces
Height systems
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

7. Introduction This course: Ellipsoidal Earth:
Concept of best fitting ellipsoid
Ellipsoid parameters
Geodetic coordinates
Radii of curvature
Curves on ellipsoid surface
Coordinate transformations:
Local- global
Astronomic- geodetic
Curvilinear- Cartesian
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

8. Introduction This course: Celestial coordinate systems:
Horizon
Equatorial
Ecliptic
Transformations
Inertial frames and Earth’s rotation
Time systems:
Sidereal, solar, atomic
Dynamic coordinate systems:
Satellites and their orbits
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

9. Importance of geodesy Surveying has a symbiotic relationship
with some other sciences.
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

10. Introduction: Text books and references:
Fundamentals of Geodesy- lecture notes, UoC
Geodetic positioning computations- lecture notes- UoC
Geodesy- W. Torge
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

11. What is geodesy?
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

12. What is geodesy?
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

13. What is geodesy?
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

14. What is geodesy?
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

15. Basic concepts are the same today, GPS are the new ‘stars’
Introduction
Historical development of geodesy
Basic concepts are the same today, GPS are the new ‘stars’
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

16. Historical development
Pythagoras (~ BC)
Suggested earth as sphere.
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

17. Eratosthenes Eratosthenes (276-195 BC) “Father of Geodesy”
First to make measurement of size of earth
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

18. Eratosthenes
Measured length of shadow from a gnomon at noon in Alexandria at the summer solstice.
In Syene, which was assumed to be on same meridian and known to lie under the Tropic of Cancer, sun’s rays reached the bottom of a well.
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

19. Eratosthenes Eratosthenes (215 BC) S = 4400 stadia ~787 km
 = 7.2o, C = km
R  6371 km
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

20. Eratosthenes  N d R S Alexandria Syene N S  d R
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

21. Eratosthenes How was distance measured?
1. Camel caravan traveled 100 stadia/day and took
about 50 days to travel distance.
2. Probably determined by Egyptian cadastral maps made by ‘bematists’ clerks who measured distances by walking evenly and counting their steps).
Calculated distance 5000 stadia therefore circumference of earth 250,000 stadia
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

22. Eratosthenes
Difficulty in converting stadia into meters therefore one estimate is the circumference is too large by 16% and another 0.6% too Small.
Errors:
1. Sun could not be directly overhead at time of
measurement off by about 22′.
2. Alexandria and Syene not on same meridian.
3. Unit conversion problem.
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

23. Newton Isaac Newton (1642-1727 AC) mathematician and physicist
Suggested earth as ellipsoid.
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

24. Newton
Newton demonstrated that the concept of a truly spherical earth was inadequate as an explanation of the equilibrium of the ocean surface. He argued that because the earth is a rotating planet, the forces created by its own rotation would tend to force any liquids on the surface to the equator. He showed, by means of a simple theoretical model, that hydrostatic equilibrium would be maintained if the equatorial axis of the earth were longer than the polar axis.
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

25. The shape of the earth
By the figure of the earth we mean the topographical (physical) and the mathematical surface of the earth. The physical surface of the earth is the border between the solid or fluid masses and the atmosphere.
As the earth's surface is irregular then you should modeling it by mathematical one.
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

26. Spheroid / Ellipsoid
Spheroid is a solid generated by rotating an ellipse about either the major or minor axis.
Ellipsoid is a solid for which all plane sections through one axis are ellipses and through the other are ellipses or circles.
If any two of the three axes of that ellipsoid are equal, the figure becomes a spheroid (ellipsoid of revolution).
If all three are equal, it becomes a sphere.
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

27. 2D Ellipsoid / Spheroid
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

28. 3D Ellipsoid
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

29. Geoid
The real shape of the earth is approximated by the Geoid or mean sea level that is a surface of constant gravity potential (equipotential surface).
What we call the surface of the earth in the geometrical sense is nothing more than that surface which intersects everywhere the direction of gravity at right angles, and part of which coincides with the surface of the oceans.
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

30. Geoid
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

31. Geoid and Ellipsoid
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU

32. Geoid and Ellipsoid
Dr.A'kif Al_Fugara, Dept. of Surveying, AABU