Question 1 of 45Geodesy & GNSS · Recall
Geodesy works with three distinct surfaces: the terrain, an ellipsoid of revolution, and the geoid. Which statement correctly identifies the geoid?
Practice · 45 questions
Geodesy & GNSS
Datums, coordinate systems and satellite positioning: the ellipsoid and the geoid, NAD 83 and NAVD 88 and their modernized successors, State Plane, and how GNSS observations are made and processed.
What this subject area expects
- Distinguish ellipsoid height, orthometric height and geoid height, and relate them
- Explain the difference between a horizontal datum, a vertical datum and a projection
- Apply grid, elevation and combined factors between ground and grid distances
- Describe static, RTK and network-RTK observation methods and their error sources
Topics covered here
Ellipsoid, geoid and terrain · Ellipsoid, orthometric and geoid heights · Horizontal and vertical datums · NSRS modernization · State Plane Coordinate System · Grid, elevation and combined factors · Ground and grid distances · Convergence and grid azimuth · UTM and low-distortion projections · US survey foot and international foot · GNSS signals and observables · GNSS field methods and processing · GNSS error sources and quality
Other subject areas
All 7- MathematicsThe algebra, geometry and trigonometry that every other domain assumes — right triangles, the law of sines and cosines, coordinate geometry, areas and volumes.
- Basic sciencesPhysics and applied science a surveyor meets in the field: light and EDM, temperature and tension effects on a tape, statics, hydrology basics and units.
- Geomatics fundamentalsInstruments, field procedures and the data that comes off them: levels, total stations, differential levelling, traverse field work, notes and data reduction.
- Plane surveyingThe computational heart of the exam: traverse computation and adjustment, area, curves both horizontal and vertical, earthwork, and construction staking.
- Boundary conceptsGeneric, nationally applicable boundary principles — the PLSS as described in the BLM Manual of Surveying Instructions, the hierarchy of calls, retracement, riparian concepts and record research. No state-specific statutes.
- Measurement analysisError theory as an exam actually tests it: systematic versus random error, standard deviation, propagation through sums and products, weights, and closure tolerances.