Hartley Wintney, July 15th 2009 - Getmapping has delivered a new aerial photographic map to South Gloucestershire Council. Unusually the imagery was captured in 1991 and until recently lay dormant as negatives in the old Avon County Council film archive. Getmapping scanned each negative and processed the resulting digital files to produce a geographically accurate and seamless digital layer for use across the Council’s planning and archeology departments. The imagery is highly detailed with each image pixel equivalent to 25 cm on the ground.
At South Gloucestershire, aerial imagery is a widely used planning tool. Using sophisticated geographic information systems planners can view current maps in conjunction with with several layers of aerial photography captured at different times, 1999, 2005/6, 2008/9 and now 1991.
“Instead of negatives left gathering dust in the archive we now have a really useful high quality geographically accurate map of South Gloucestershire in 1991 which planners can use along with more recent imagery to review and assess planning applications and development plans. In this imagery for example we can see the landscape setting of Avon prior to the construction of the Avon Ring Road, or can use it to discover hitherto unknown archaeological sites that may have been affected by development. There is real value in being able to view and interrogate imagery from different time periods whether it is to ensure planning compliance or to record and secure our archaeological heritage,” said Paul Driscoll, Historic Environment Record Assistant at South Gloucestershire Council.
Aerial photography is one of the best ways of understanding archaeological landscapes, because it reveals and makes sense of surface and sub-surface features, which are often too feint, too large or too discontinuous to be ascertained at ground level. These can occur as earthworks, crop marks, soil marks or parch marks. Aerial photography can reveal different features dependent on several factors including the time of the year and the amount of rainfall. The hot summers of 1975-76 and 1994-95 in Britain for example are particularly noted for producing parch-marks, leading to the discovery of many new sites such as prehistoric settlements and enclosures, medieval field patterns and furrows.
Getmapping has access to a wide range of aerial film archives many of which are suitable for conversion for use with modern digital mapping systems.