Caribbean datums and the integration of geographical data

Modern electronic positioning systems are capable of locating a point in the vicinity of the Earth’s surface to very high precision. Depending on the sophistication of equipment in use, whether the requirement is relative or absolute and the data processing time available, accuracy from 10 m down to a few millimetres can be achieved in three dimensions. While it is not difficult to measure the position of a point using today’s technology, it can be problematic to relate measurements made today to those made in the past. Advances in applications such as Geographical Information Systems (GIS) for example, that integrate geographic data from a wide range of sources may give misleading results if one position on the surface of the Earth can have a number of different coordinate values. This paper is aimed at explaining the reasons behind such dilemma while giving particular examples that relate to the Caribbean region. It defines and explains the different conventions that are adopted while providing local parameters that enable conversion between modern and some of the traditional datums. The reliability of this information is shown to be variable and there is a need for improvement in the quality of parameters that are made publicly available.