Click here to view 0.5M GSD photography from 2008 onwards
In 2005, National Geo-spatial Information noticed a global trend towards digital image acquisition and decided to invest in a digital camera (an Intergraph DMC). Since 2008, all images have been captured digitally with this camera.
This meant that the acquisition of the traditional photo-scale had now been replaced with a Ground Sample Distance (GSD). The ground sample distance is the size of 1 pixel on the ground and is influenced by the flying height and focal length.
National Geo-spatial Information (NGI) is the government component responsible for aerial photography and has an archive of aerial photographs dating back to the 1930's. The photography is at a variety of scales and has provided complete coverage of the country since the 1950's. These are all vertical aerial phtographs taken from aircraft. Photography is continuously reflown to provide new photography for ongoing map revision and for sale to users.
Unlike a generalised line map, almost all detail is visible on an aerial photograph. The user, although unable to make accurate measurements on the photograph, is able to perform his or her own interpretation of what exists on the ground. Aerial photographs are also an historic record of what existed at the time the photograph was taken.