intro Flashcards
(15 cards)
What are the three main goals of geodesy?
1) Establish 3D geodetic networks,
2) Measure geodynamic phenomena,
3) Determine Earth’s gravity field.
What is a one-dimensional geodetic network?
A network based on elevation (height) above mean sea level.
What instrument is primarily used in vertical (1D) geodetic networks?
The levelling instrument.
tide gauges.
What is the vertical datum commonly based on in 1D networks?
The geoid (mean sea level).
When and where was Kenya’s first tide gauge installed?
In 1933 at Kilindini, Mombasa.
What are two modern tide gauge locations in Kenya?
Liwatoni Jetty (Mombasa) and Lamu.
What is a two-dimensional geodetic network?
A network based on horizontal coordinates (latitude and longitude).
What traditional method is used to establish 2D geodetic networks?
Triangulation.
What is the current trend in establishing geodetic networks?
Transitioning to GNSS-based 3D networks.
What is three-dimensional geodesy?
A method that integrates horizontal and vertical positioning into one model.
Who first proposed the idea of 3D geodesy?
Bruns (1878) and Villarceau (1868).
Why was 3D geodesy not initially practical?
Due to unreliable height measurements and lack of geoidal data.
What technology enabled practical 3D geodesy?
Satellite positioning systems like GPS and GNSS.
What are common observation types in 3D geodesy?
Spatial distances, angles, zenith angles, and astronomical measurements.
What are current challenges in geodesy?
Integrating classical 1D/2D networks with GNSS-based global systems and mapping the geoid.
