The expansion of Global Navigation Satellite Systems (GNSS, including GPS) is changing the classical geodetic approach based on two reference models - the horizontal component (Geodetic Network) and the vertical component (Levelling Network) which were independently established - by replacing it with a single three-dimensional reference model where all coordinates are obtained in the same way. GPS height (above WGS84 ellipsoid) can be associated with orthometric height (above mean sea level and measured along the plumb line) without losing excessive accuracy, while incorporating an additional geodesic component: gravity.
Maintaining stable references in a Geodetic Infrastructure requires incorporating the time variable due to, among other things, the movement of the Earth's continental plates (Europe is separating from North America at a rate of 3 cm per year). The objective of the project, which started in 2002, is to improve the accuracy and density, and further develop a four-dimensional Geodetic Infrastructure in Gipuzkoa, taken to be a local densification of the current European (ETRS89) and global (ITRF2005) Geodetic Reference Frames.
Administrations or individuals that wish to share their data/experience are welcomed as Gipuzkoa's Geodetic Infrastructure has a user-oriented approach.