This paper sets out to discuss ongoing activities in the tide and chart datum components of hydrography and charting. It expands on the paper presented at FIG (Fédération Internationale des Géomètres) in Brighton 1998 by Mr Matt Higgins and is a revised and updated version of the paper Chart Datum for Hydrography by GPS delivered by the present authors to the Survey 99 Congress, Sunshine Coast,...

Instantaneous, reliable and fit-for-purpose positioning and time services across Australia are the aims of the National Positioning Infrastructure policy. Indeed, it is already possible to achieve centimetre-level positioning almost anywhere (outdoors) and anytime, following advances in positioning technologies over the last few decades. Not surprisingly, this capability has highlighted limitat...

In 1998 Land Information New Zealand introduced New Zealand Geodetic Datum 2000 (NZGD2000) as its new national datum. It is defined as a semi-dynamic datum and incorporates a national deformation model to ensure that the accuracy of the datum is maintained. The deformation model allows observations made at an epoch other than the datum reference epoch of 2000.0 to be modeled so that coordinates...

The need for a new vertical datum in Canada dates back to 1976 when a study group at the Geodetic Survey Division (GSD) of Natural Resources Canada investigated problems related to the existing vertical reference system (CGVD28) and recommended a redefinition of the vertical datum. The US National Geodetic Survey and GSD cooperated in the development of a new North American Vertical Datum (NAVD...

A common problem faced by most countries is the estimation of precise transformation parameters between their national geodetic datum, and the World Geodetic System 1984 (WGS84) global datum, used by the Global Positioning System (GPS). There can be considerable difference in positions of the local ellipsoidal datum and the global datum, sometimes up to several hundred meters. So a country like...

A definition of a Doi-Koppinen datum over a noncommutative algebra is proposed. The idea is to replace a bialgebra in a standard Doi-Koppinen datum with a bialgebroid. The corresponding category of Doi-Koppinen modules over a noncommutative algebra is introduced. A weak Doi-Koppinen datum and module of [1] are shown to be examples of a Doi-Koppinen datum and module over an algebra. A coring ass...