Understanding Geodetic Reference Data

TBC uses a coordinate system (also referred to as a coordinate reference system) to transform measurements on a curved surface (the earth) to a flat surface (a map or plan). For example, a coordinate system is used to calculate grid coordinates for a point measured using GNSS.

A coordinate system can include the following elements:

datum transformation
Also referred to as a coordinate transformation (see ISO 19111:2019).
A datum transformation provides the parameters that you need to convert coordinates from one datum to another. It defines the transformation that must be applied to transform points defined in terms of one datum to their equivalent position in terms of a different datum.
projection
Also referred to as a map projection (see ISO 19111:2019).
A mapping of a set of coordinates from a datum to a plane; or a set of mathematical rules for performing such a translation. Projections are used to create flat maps that represent the surface of the earth or parts of it.
See also coordinate system, coordinate projection methods, grid, and mapping projection.
geoid model

A mathematical representation of the geoid for a specific area or for the whole earth. TBC uses the geoid model and the latitude and longitude of the points to generate geoid separations for your points in the network. See also geoid, geoid separation.
site calibration

The process of computing parameters that establish the relationship between WGS-84 coordinates (latitude, longitude, and ellipsoid height) determined by GNSS observations and local known coordinates determined by a map projection and elevations above mean sea level. The parameters are used to generate local grid coordinates from WGS-84 (and vice-versa) in real-time in the field when using RTK surveying methods.

You must select a coordinate system for every project. If you do not have a system, or do not know which system to select, use the default projection.

Note: Make sure that the points in a project are within a reasonable distance from the projection origin according to the properties of the projection used.

Coordinate system database

The coordinate system database is stored as a file called Current.csd. It contains all of the coordinate system information. The office software supplies an extensive set of published coordinate systems from around the world. To define or edit coordinate systems, zones, sites, datum transformations, ellipsoids, and geoid models, use the Coordinate System Manager.