How Accurately Can We Determine Orthometric Height Differences from GPS and Geoid Data?

A data-driven approach to local gravity field modelling using spherical radial basis functions

“…Said earlier, sometimes full variance-covariances are available for individual data sets; this information cannot be easily combined with the proposed data combination strategy based on the formulation as a Cauchy boundary-value problem. Then, a generalized LSC approach as proposed by Kotsakis and Sideris (1999) and applied by Fotopoulos et al (2003) may be appropriate.…”

GNSS in Practical Determination of Regional Heights

“…In order for GNSS derived ellipsoidal heights to have any physical meaning in application, they must be transformed to orthometric heights referring to mean sea level (geoid). This transformation is applied using the geoidal heights (N) from a geoid model that must be known with sufficient accuracy (Fotopoulos et al, 2001;Fotopoulos, 2005). The computation methods of geoid models are many (Schwarz et al, 1987;Featherstone, 1998;Featherstone, 2001;Hirt and Seeber, 2007;Erol et al, 2008;Erol et al, 2009).…”

“…The data quality, density and distribution of the reference benchmarks have important role on the accuracy of local GNSS/levelling geoid model (Fotopoulos et al, 2001;Fotopoulos, 2005;Erol, 2008Erol, , 2011. There are certain criteria on the geoid reference benchmark qualities and locations, as described in the regulations and reference books (LSMSDPR, 2005;Deniz&Çelik, 2007) that will be mentioned in the text that follows.…”

“…The level of achievable accuracy of the models varies depending on the computational methodology (assumptions used) and available data within the region of interest Fotopoulos, 2003;Fotopoulos et al, 2001;Erol, 2007;Erol et al, 2008). The regional models provide better accuracies in comparison to global models.…”

Analysis Model to Optimize Ground Stations in Built-up Areas

“…To mitigate or eliminate errors within the position calculation there are techniques to solve them: averaging repeated observations, applying correction values by predicting causes of error, and applying differential corrections (Wu & Yiu, 2001;Schön et al 2005;Fotopoulos et al 2003;Featherstone & Stewart, 2001;Mauro et al 2010). In addition, RTK (Real Time Kinematic) which is a technique that enables high accuracy using carrier-based ranging, provides ranges and therefore positions reducing and removing errors common to a base station (Jonson et al 2003;Brown et al 2006;Cai et al 2011;Sioluis, 2015).…”