Geodesy is the science concerned with accurately measuring and mapping the shape, size and gravity field of the Earth. In construction, geodesy is the basis for dimensional accuracy, setting out buildings and determining heights.
How geodesy works
Geodesy combines mathematics, physics and measurement technology to fix positions on Earth relative to a reference system. These use national coordinate systems for horizontal position and a vertical datum for height. Key measurement methods are:
- GPS/RTK – satellite positioning with centimetre accuracy.
- Total station – an instrument that measures angles and distances.
- Levelling – precisely determining differences in height.
With these techniques, surveyors record exact coordinates and elevations.
Application
In construction practice, geodesy is used for:
- Setting out – transferring the drawing onto the building site.
- Dimensional control – checking positions, heights and squareness.
- As-built surveying – recording existing situations.
- Monitoring – measuring settlement and deformation of structures.
Accurate geodesy prevents construction errors and ensures that foundations, walls and services end up in exactly the right place.
Related terms
- Surveying
- Dimensional accuracy
- Setting out
- Vertical datum
- Foundation
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