The Recording System

Since 2002, Wessex Archaeology has developed a Microsoft Access based diver recording system known as ‘DIVA’ which can be used for real time recording of three-dimensional positions and information in conjunction with the mapping programme ESRI ArcGIS 9.0.

DIVA consists of a Microsoft Access database which stores the information, and a GIS interface for graphic display. This system was used in Round 1 of the project and has since been further improved.

The position of the tracked vehicle or diver is output from the Sonardyne SCOUT surface command module in real world co-ordinates and can consequently be displayed in real time on top of geophysical survey data in ArcGIS 9. The vehicle or diver track can also be displayed and saved separately

To allow integration with the previously acquired geophysical survey data, Universal Transverse Mercator (UTM) coordinates, based on the WGS84 datum and the WGS84 ellipsoid were used for display and recording. The targeted wrecks were spread over UTM zones 30N and 31N.

A laptop running DIVA and ArcGIS was set up in the survey container, so that the recorder could see the screens showing the underwater footage being collected by the ROV and divers.

Observations made by divers or recorded from the Remotely Operated Vehicle video feed can be entered into the database by the recorder. These observations, stored in the DIVA database, include the three-dimensional position, comments typed in by the recorder and mapping labels for the display in the GIS system.

Observations can be taken as quick, but less accurate, spot fixes, or as average fixes. Average fixes obtain a number of positions over a short period of time and calculate an average position for the diver or tracked vehicle using a software application developed by Wessex Archaeology and known as Accu-fix. The more accurate average fixes were generally used for recording datum points and important features on the wrecks.

Diver observations can be displayed as different layers in ArcGIS, grouped for example by mapping labels, observation type, etc.

A summary form allows the archaeological supervisor to summarise individual dives, whole events and monuments. The diver can also enter archaeological, environmental and operational summaries. Paper records such as drawings can be referenced to individual diver observations.

A general log allows the archaeological supervisor to keep track of daily events, working hours, weather forecast and tidal predictions.

Records of earlier events, such as the Round 1 diving or the collection of geophysical data were readily available in the DIVA database. This was a useful source of reference and comparison, especially where earlier diver observations were concerned.