Ellipsoidal distances in CSDs
Distances measured or calculated in a Cadastral Survey Dataset (CSD) must be reduced to the datum ellipsoid. These distances (also known as spheroidal distances) can be approximated by the horizontal distance at mean sea level.
Projection distances are often incorrectly included in CSDs where:
- survey work has been undertaken using Global Navigation Satellite Systems (GNSS), and
- distances are calculated to trigs using projection coordinates.
Landonline has been designed to accept ellipsoidal distances only; it then generates the projection correction where this is required. Therefore, a CSD lodged with projection distances causes difficulties with integration into Landonline. Projection distances will also cause difficulty for future surveyors who will have to spend time identifying and reporting on the differences between surveys.
Take care to ensure your work complies with Rule 22 of the Surveyor-General's Rules for Cadastral Survey 2002/2, which requires the use of ellipsoidal distances.
