SOUTHAMPTON-based Ordnance Survey has launched a major programme to improve some of its most popular mapping.

New technology such as the Global Positioning System and digitally scanned aerial photography, means greater accuracy than ever before and this is all to be used to boost the positional accuracy of the 1:2,500 scale mapping.

The mapping agency believes that it is important to tackle this now to ensure its rural areas map data meets modern quality standards and to ensure that the accuracy level will be suitable and acceptable in the future when new developments and other changes need to be incorporated.

Ordnance Survey's Jim Page says: "To put the task ahead into context, the area of Britain is just over 230,000 square kilometres and Ordnance Survey maps around 158,000 of them at 1:2,500 scale. The biggest impact of the improvement programme will be on less than two per cent of the 1: 2,500 scale mapping.

"These cover small towns and peri-urban areas and will be completely resurveyed or reformed to a higher accuracy to achieve the same quality standard as our current 1:1,250 scale mapping.

"There will be changes on the majority of the other 1:2,500 scale maps as well to meet a consistent absolute accuracy standard, but the number of features affected will be less.

"As geometric fidelity and relative accuracy will be maintained, typical land parcel areas are not expected to change by more than two per cent.

"Nonetheless, we know it will be a pain for some of our land-line data customers, who will be most affected by these improvements, but we hope they will understand that it's short-term pain for long-term gain.''

The national positional accuracy improvement programme of 1:2,500 scale map data will start in April and up-to-date information about the programme's progress can be found on the internet at www.ordnancesurvey.co.uk/