Understanding localization: how to define a local coordinate system by known points

What is localization?

One of the starting points of any survey is to choose a suitable local coordinate system for the area you want to survey. In most cases, coordinate systems are optimized for that particular location. However, sometimes this just doesn’t work. You simply don’t have the necessary coordinate system parameters, or they are not accurate enough. This is where localization comes in: the only requirement for this is the availability and applicability of benchmarks or known points.

Localization, also known as site calibration, is the process of comparing sets of known and measured point coordinates in GNSS software to calculate or adjust the local coordinate system parameters. Known points must have local coordinates (measured in feet or meters), and measured points (as global coordinates in degrees).

Known and measured points for localization

During the calculation process, the software applies a series of transformations such as translation, rotation, scaling for horizontal adjustment, and inclined plane for vertical adjustment. The app then creates the best possible site reference frame, i.e. a coordinate system.