Not since William the Conqueror recorded England in the Domesday Book has there ever been such a record of the country. A record that is so detailed as to show every road, every house, and every tree - the first ever complete and continuous colour aerial photographic record.
To set about the collection of such a data set is no ordinary task. The flight planning alone was groundbreaking in its enormity. Four specially modified aircraft are on constant standby waiting clear weather and Air Traffic control permission, each one fitted with a large format forward motion compensating camera. To date over 800 hours of flying have been completed using some 54 kms of film!
Not content with simply photographing the whole country, Getmapping have used the Global Positioning Satellite (GPS) network to give them the accuracy to overlap each image by 60%. This process results in the production of stereo pairs of photographs, needed for certain types of photogrammetry and 3D viewing.
With the photography in the can, Getmapping then undertook to digitise and geo-correct the image, a process that removes all optical distortion from the images and ensures a perfect match to conventional mapping. To date some 200,000 man-hours have been invested in the project, resulting in a data set of over 20 terabytes. But a data set of this size brings its own problems. To understand the size, perhaps one should imagine that if one byte of information weighed a gram, then 20 terabytes would be equivalent to 8 fully loaded super tankers!
With these technical processes complete, there are of course the aesthetic issues to address, not least of which is ensuring a constant colour balance across the entire country. With the data collected over an extended period this is no mean feat but with the wonders of modern technology and the expertise of the Getmapping team the results are truly amazing. As you look through the pages of "England, the photographic atlas" you move seamlessly across the country from major city to secluded beauty spot, you trace journeys you have taken, and see the effect mankind has had on our landscape. You see the country as never before.
Date: 1 December 2001
Add a comment