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1ce31 August 
ORDNANCE SURVEY: IMAGERY APPLICATIONS IN SUPPORT OF 
A NATIONAL GEOSPATIAL DATA INFRASTRUCTURE 
Keith Murray - Development Manager 
Alison Davey - National Geospatial Database Programme 
& Graham Tait - Photogrammetric Development 
Ordnance Survey, Southampton, SO16 4GU, United Kingdom 
Commission VI 
KEY WORDS: GIS, SPATIAL, ECONOMY, THEMATIC, APPLICATION, IMAGERY, DEVELOPMENT 
ABSTRACT: 
Of all its 200^ year history the past five years have perhaps been the most challenging for Britain's national mapping 
agency. The challenges have been met with success in the completion of the national digital large scale database in 
1995, the completion of a national address database in early 1996 and a national high resolution digital height model. 
Having prepared a continuous model of Britain's topography it would now be easy to sit back and enjoy the fruits of our 
labours. That will not happen if we are to retain and build our customer base for geospatial data well into the next 
millennium. To encourage usage of data, not just that of Ordnance Survey (OS), but any geospatially related data in 
Britain, OS has proposed the concept of a National Geospatial Database. The national benefits of integrating data from 
various government bodies clearly has great potential and this is already being proven in the current trial of a National 
Land Information Service (NLIS). 
The most expensive aspect in maintaining geospatial data is the data collection and update process. Imagery has 
played a significant role in minimising those costs over the past 40 years. Technology is now taking us into new areas 
where computing and networking power is starting to realise the early visions of increased automation. This paper 
describes areas of recent advancement and a major research investigation into the potential of high spatial resolution 
space sensors programmed for launch in the near future. It is already clear that imagery will play an increasing role in 
maintaining the geospatial databases of the future. 
1.2 The database and its products 
1. ORDNANCE SURVEYG 
Britain now has a database which models urban areas at 
a nominal survey scale of 1:1 250, minor towns and rural 
areas at 1:2 500 scale and mountain and moorland areas 
at 1:10 000 scale. 1996 will also witness the completion 
of the digitising of a national height dataset based on 
photogrammetric contour surveys (5 and 10 m vertical 
interval). The address database holds a 1 m National 
Grid reference for over 23 million addresses. Further 
databases | model road networks, administrative 
boundaries and various medium and smaller scale 
equivalents. 
1.4 National Mapping Agency 
The past five years has witnessed a number of major 
events and achievements that rank in significance even 
when compared with the celebration by Ordnance 
Survey (OS) in 1991 of 200 years continuous operation 
in providing Britain with a rich mapping base. In early 
1995 national large-scale digital data coverage was 
completed, a national on-demand plot service was 
launched later that year, and more recently the creation of 
a national address database was also completed. All this 
was achieved concurrently with a major internal 
reorganisation to refocus key elements of the 
organisation on specific business operations. The next 
five year period looks to be equally challenging! (Rhind 
1995). 
The main topographic database contains 230,000 data 
tiles and serves a wide range of customers, our own 
survey operation - including the work done by contractors. 
During February 1996 the database reached a new peak 
of operational performance over a three week period 
when an access request was serviced on average every 
; 2.4 ds (based on a 22 hour operational day). 
Ordnance Survey has been a government Executive seconds ( perational day) 
Agency since 1990 and has been increasingly successful 
in improving its position as the leading supplier of 
geospatial data and information in Great Britain. OS 
revenue was £58m during the financial year 1994/95. 
This is equivalent to a 7896 return on annual expenditure 
and is globally highly unusual amongst national mapping 
agencies (Ordnance Survey 1995b). 
The topographic database currently holds in excess of 
200 million features, this includes building outlines, walls, 
fences and hedges, road limits, names, water features 
etc. which are managed together to create and maintain a 
continuous model of the nation. 
99 
International Archives of Photogrammetry and Remote Sensing. Vol. XXXI, Part B6. Vienna 1996