Jim Turner

• BSc MSc PhD
• University College London

This paper provides a summary of innovative approaches developed on Snake Projection coordinate transformations that maximise data interoperability and compatibility within CAD, GIS and survey software and systems. The project’s topographical survey, design and construction use an engineering coordinate system defined by the HS2 Snake Projection t...

The Vertical Offshore Reference Frames (VORF) project is described, with a summary of the methodology and an explanation of the data sets used. The latter include satellite altimetry, tidal and geoid models, long and short term tide gauge data, and specially undertaken GNSS observations. This paper goes on to describe the theoretical basis for deri...

The UK Hydrographic Office (UKHO)-sponsored Vertical Offshore Reference Frames (VORF) project aims to develop tidal level transformation models that are referenced to the GRS80 ellipsoid and thus compatible with GNSS positioning; in particular, heighting. Benefits include increasing the efficiency of hydrographic surveying, providing a stable consi...

“Trixel Buffers is a new spatial data-structure for fast point in multiple polygon inclusion queries. The algorithm utilizes a pre-processing step in which the inside/outside status of a quadtree´s leaf triangles without polygon geometry is pre-computed automatically; at run-time point queries lying within these triangles simply inherit their inclu...

As part of the U.K. Hydrographic Office (UKHO)-sponsored Vertical Offshore Reference Frames (VORF) project, a high-resolution model of lowest astronomical tide (LAT) with respect to mean sea level has been developed for U.K.–Irish waters. In offshore areas the model relies on data from satellite altimetry, while in coastal areas data from a 3.5-km-...

As part of the Vertical Offshore Reference Frames (VORF) project sponsored by the U. K. Hydrographic Office, a new model for Sea Surface Topography (SST) around the British Isles has been developed. For offshore areas (greater than 30 km from the coast), this model is largely derived from satellite altimetry. However, its accuracy and level of deta...

This paper describes work carried out to produce a continuous model of Chart Datum (CD) in UK and Irish waters with respect to the widely used satellite coordinate reference systems, ETRF89 and ITRF2000. The overall methodology is described, in which (a) offshore datum surfaces are computed by adding modelled tides to a mean sea surface determined...

The Vertical Offshore Reference Frame (VORF) is a project tasked to integrate all vertical datums and reference surfaces used in the UK and Eire; particularly the sea datums used as the basis for marine charting, the land datums used for expressing height above sea level, and the reference frame used for GPS/GNSS positioning. The project was commis...

For over 150 years traditional bathymetric and topographic measurements have been collected independently to serve different purposes. Today depth and height data tend to be referred to different vertical datums which creates inconsistency across the land-sea interface. Depth datums, in particular are usually referred to local tidal datums (Chart D...

In GiS Pro’s first issue Dr Jonathan Iliffe noted the challenge of integrating data in the coastal zone due to the range of vertical datums in use. Collaborative research between UCL and UKHO is rising to that challenge.

A preliminary commission error analysis whereby orbit perturbation theory and other techniques are used to assess and predict the recovery of the Earths gravity field from the challenging microsatellite payload (CHAMP) mission is developed and implemented. With CHAMP launched in July 2000, accumulated evidence is now available to quantify the error...

Results are presented from precise orbit computations of CHAMP using a reduced dynamic procedure within the GIPSY/OASIS software. Details are given of the orbital strategy and tuning process for the kinematic stochastic accelerations. The accuracy of the orbits is quantified by overlap residuals, by comparison against independent orbits submitted t...

In this chapter we outline the methodology in use at Newcastle University to recover the static and time varying gravity field from the CHAMP mission. Details are presented of the reduced dynamic process adopted within the JPL software GIPSY-OASIS II to recover precise ephemerides from the GPS code and phase data with orbit overlaps and tracking re...

Results are presented from precise orbit computations of CHAMP using a reduced dynamic procedure within the GIPSY/OASIS software. Details are given of the orbital strategy and tuning process for the kinematic stochastic accelerations. The accuracy of the orbits is quantified by overlap residuals, by comparison against independent orbits submitted t...

Thesis (Ph. D.)--University of Newcastle upon Tyne, 2002.