The increased use of GNSS for technical constructions and infrastructure works makes necessary the calculation of local accurate geoid undulation’s models for the determination of accurate orthometric heights. Apart from the conventional methods, artificial neural networks (ANN) are also used for this purpose. Specially, back propagation artificial neural networks (BPANN) are widely applied for...

in many countries, leveling networks are established for height determination which is one of the most important topics in geodesy. in these networks, the sum of the leveled height differences between a and b will not be equal to the difference in the orthometric heights ha and hb. the reason is that the leveling increment ?n, as we henceforth denote it, is different from the corresponding incr...

A subsidence research program began in 1985 to document the extent and magnitude of land subsidence in Sacramento Valley, California, an area of about 15 600 km, using Global Positioning System (GPS) surveying. A brief description of GPS surveying is followed by a summary of each of four surveys between 1985 and 1989. In addition to periodic conventional spirit levelling, an examination was mad...

The GPS meteorology (GPS/MET) experiment, led by the Universities Corporation for Atmospheric Research (UCAR), consists of a GPS receiver aboard a low earth orbit (LEO) satellite which was launched on 3 April 1995. During a radio occultation the LEO satellite rises or sets relative to one of the 24 GPS satellites at the Earth's horizon. Thereby the atmospheric layers are successively sounded by...

We propose a methodology for local gravity field modelling fromgravity data using spherical radial basis functions. The methodology comprises two steps: in step 1, gravity data (gravity anomalies and/or gravity disturbances) are used to estimate the disturbing potential using least-squares techniques. The latter is represented as a linear combination of spherical radial basis functions (SRBFs)....