Hartley Wintney, March 30th 2009 - Getmapping has announced a new enhanced height dataset of Scotland derived directly from its aerial photographic survey of the country. Processing for the rest of the Britain is now underway. The arrival of a new more accurate height model will be welcome coming shortly after scientists at the recent climate change summit in Copenhagen said that earlier UN estimates for sea levels were too low. Height data is used for numerous earth studies including impact assessments for rising sea levels and flood modelling.

In 2006 Getmapping became involved in a DTI co-funded Knowledge Transfer Partnership (KTP) with Bath Spa University, Geosense and SCS. The remit was to provide a more accurate nationwide height dataset at lower cost. The result is a new methodology for producing height data from stereo aerial photography. While it has always been possible to create highly accurate height data from vertical aerial photography using photogrammetry it was time consuming and expensive to carry out. However as a result of the KTP project, new workflows and algorithms have refined and speeded up the process to deliver the best possible balance between accuracy and cost. The result is significantly more accurate than Radar (SAR), less costly than LiDAR (Light Detection and Ranging) and provides nationwide coverage.

The new eDEMs (enhanced Digital Elevation Models) consist of a first surface model (DSM) and a digital terrain model (DTM), contours will be added in due course. In open areas accuracy is comparable to LiDAR but out performs it in urban areas by virtue of the ability to extract building detail photogrammetrically. The datasets are considerably enhanced by aerial photography providing the ‘intelligence' to aid interpretation and risk assessment and opening the way for 3D visualisation. The data is available in one square km tiles and is therefore very cost effective.

"Height data provides the third dimension in a land survey, and is a vital resource for analysing the risks associated with climate change, such as flooding and the threat of attack from the sea. It is also invaluable for use in planning and 3D visualisation," said Tristram Cary, Managing Director of Getmapping. "This Knowledge Transfer Project is a brilliant example of co-operation between government, academia and the private sector producing what we believe to be the best product for the market," continued Cary.

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