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3.9. Geodesy (GEO)

This knowledge area covers the science of measuring and representing the Earth's shape, orientation, and gravity field: geodetic reference systems and datums, control network design and adjustment, physical geodesy, and satellite-based precise positioning.

Knowledge Area (KA)	Core Tier1	Core Tier2
3.9.1 Geodetic Fundamentals and Reference Systems	Elective
3.9.2 Geodetic Control Networks	Elective
3.9.3 Physical Geodesy and the Gravity Field	Elective
3.9.4 Satellite Geodesy and Precise Positioning	Elective

3.9.1. GEO/Geodetic Fundamentals and Reference Systems ↑ Back to top

Earth shape models, geodetic datums, and the coordinate and reference-frame systems that underlie every geodetic measurement.
Topics:
Core

• Earth shape models: the reference ellipsoid and the geoid
• Horizontal geodetic datums and their realization
• Vertical geodetic datums and height reference surfaces
• Global reference frames (ITRF, WGS84) and their realization and maintenance
• Geodetic, geocentric, and projected coordinate systems and conversions between them

Learning Outcomes:
Core:

1. Distinguish the reference ellipsoid from the geoid and explain their respective roles [Familiarity]
2. Select an appropriate horizontal and vertical datum for a given project [Usage]
3. Transform coordinates between global reference frames (e.g. ITRF realizations) [Assessment]
4. Convert coordinates between geodetic, geocentric, and projected coordinate systems [Usage]
5. Explain how a geodetic datum is realized and maintained over time [Familiarity]

3.9.2. GEO/Geodetic Control Networks ↑ Back to top

Design, adjustment, and accuracy classification of the horizontal and vertical control networks that densify a country's national geodetic framework.
Topics:
Core

• Geodetic control network design: configuration, redundancy, and point selection
• Least-squares network adjustment and error ellipse interpretation
• National geodetic control networks and their institutional maintenance (e.g. Peru's IGN network)
• Control network densification for local and project-level surveys
• Geodetic accuracy standards and classification of control points

Learning Outcomes:
Core:

1. Design a geodetic control network with appropriate configuration and redundancy [Usage]
2. Adjust a geodetic network by least squares and interpret the resulting error ellipses [Assessment]
3. Describe the structure and maintenance of a national geodetic control network [Familiarity]
4. Densify a national control network for a local or project-level survey [Usage]
5. Classify a control point against its applicable geodetic accuracy standard [Assessment]

3.9.3. GEO/Physical Geodesy and the Gravity Field ↑ Back to top

The Earth's gravity field, geoid determination from gravimetric data, and the distinction between orthometric and ellipsoidal height systems that this field makes necessary.
Topics:
Core

• Gravity field fundamentals and normal gravity formulas
• Geoid models and geoid undulation determination
• Gravimetric surveying methods and instrumentation
• Orthometric versus ellipsoidal height systems and the role of the geoid in converting between them
• Application of geoid undulation to obtain orthometric heights from GNSS data

Learning Outcomes:
Core:

1. Explain the Earth's gravity field and the normal gravity formula [Familiarity]
2. Apply a geoid model to determine geoid undulation at a point [Usage]
3. Conduct a gravimetric survey and process the resulting data [Assessment]
4. Distinguish orthometric from ellipsoidal heights and explain when each is used [Familiarity]
5. Convert ellipsoidal heights from GNSS to orthometric heights using a geoid model [Usage]

3.9.4. GEO/Satellite Geodesy and Precise Positioning ↑ Back to top

Satellite orbit fundamentals and the precise GNSS positioning techniques -static baseline processing and precise point positioning- used to carry out a geodetic-grade GNSS campaign.
Topics:
Core

• GNSS geodetic positioning: static baseline processing for control-quality accuracy
• Satellite orbit fundamentals and broadcast versus precise ephemerides
• Precise Point Positioning (PPP) principles and applications
• Planning and execution of a geodetic-grade GNSS observation campaign
• GNSS error sources affecting geodetic-grade positioning and their mitigation

Learning Outcomes:
Core:

1. Process static GNSS baselines to achieve control-quality positioning accuracy [Usage]
2. Explain satellite orbit fundamentals and the difference between broadcast and precise ephemerides [Familiarity]
3. Apply Precise Point Positioning to a geodetic observation [Assessment]
4. Plan a geodetic-grade GNSS observation campaign [Usage]
5. Mitigate GNSS error sources affecting geodetic-grade positioning [Assessment]