The NEXT generation
While Nicholas Crane continues his intriguing series Map Man on BBC television, exploring the significance of historic mapping of Britain, a new map technology is becoming available that provides an accuracy that, until recently, cartographers could only dream of. However, it is not just the accuracy but the usability that means this new generation of mapping should become of immense benefit to architects.
Provided by GetmappingUK, the new maps have been developed from aerial photographic exploration of Britain. In essence, a 725km/h Lear jet has flown back and forth, up and down the British Isles (see 'What NEXT? box, opposite page) for several months following a carefully demarcated grid pattern while taking vertical images of the terrain below. Instead of these being the traditional Ordnance Survey grid-reference photographs that are developed, or downloaded as image files, these images are produced from Intermap's IFSAR (Interferometric Synthetic Aperture Radar) technology, although they are available as JPEG files. However, since they are created from radar imaging of the topography under the flight path, using stateof-the-art advanced guided missile technology, the resulting information is more detailed and has more manipulable layers.
On flying over a site, the camera reads the ground conditions, undulations, trees, fences, traffic and street furniture among other things. With elevation points taken every 5m (see box below), it provides an accuracy of 1m across the country, with double that accuracy in some parts. That means the camera picks out changes in level at 5m intervals and maps out 1m contours. For greater accuracy, there is a higher-density map offering to read topographic changes of 500mm elevational variations and, as of last month, the system has been improved using Vexcel Ultracam D cameras fixed to the underside of Piper Chieftain survey aircraft, which will provide a resolution of up to 100mm vertical variation.
This means that the radar images will provide data points distinguishing between roads and pavements.
The beauty of the technology is that the completed files can then be translated into a variety of layers that can be altered to suit requirements. The basic treatment is called 'bald earth' and removes all superfluous information to provide a terrain model only. Buildings, trees, people and boundaries can be deleted from view to show the layout of the land at the push of a button. Ideal for initial site appraisals, available in GIS (geographic information system) format, this information can be used to look at feasibility-stage proposals.
The surface modelling information - also known as the 'canopy model' - reinstates layers of natural and built environment and is useful for design and planning-stage layouts, although the detail on both can be used for production stages. Next month, the files will be available in DXF format for instant incorporation into drawing packages.
Model-making The elevational data incorporated in the survey allows a three-dimensional model of the site to be created.
Importing the data into 3D StudioMax means that architects have the opportunity to fly their clients - virtually - across the site. Especially dramatic for one-off houses in the Lake District, the fly-through can present a much more accurate representation of the actually existing conditions of the landscape and over greater distances than would otherwise be the case. Plans for incorporating this data into a proprietary STL file, to stereolithograph a physical three-dimensional model, are not in place as yet, although there should be no reason why architects couldn't try this for themselves using compatible software.
At the moment, height data is available in TXT format for GIS users, and JPEG images are the standard format for the photographs. However, by the end of the year, a vector version should be available. One of the projected uses is for clients to be able to visualise what landscape and what views they will be able to see from their window at a given orientation.
A two-dimensional or three-dimensional representation can be printed off showing the area of the proposed field of view, highlighted for clarity. Similarly, with sunlight data programmes, the client will be able to see how much of the view, or his or her own proposed property, will be in shadow at different times of the day.
Ideal for proponents of solar technology and even, given the modelling of sheltered locations, of wind turbines.
Already taken up by insurance agencies, NEXTMap, as the generic product is called, has been used to identify areas of flood risk (although, given recent weather occurences, this seems not to have been picked up by infrastructure agencies and emergency services). Simply put, the detail and accuracy of the terrain model, together with predictive programmes developed from anticipated rainfall intensities, allow flood plain data to represent graphically the real extent of river flood tides and ponding.
Essentially, insurance companies are suggesting that instead of their usual blanket postcode lottery for determining premiums for householders in 'flood-risk areas, ' they can now be more accurate in determining which houses actually carry the real risk of flooding. Theoretically, premiums will come down for those shown to be outside the real flood encroachment area, although costs (and unsellability) will undoubtedly increase for those identified as being within the blue, water-filled zone.
Information gathering GetmappingUK is reconsidering its decision that large swathes of Scotland will not be surveyed and that a significant proportion of Scotland and Wales have only been surveyed to the lower resolution. Whether this upgrading will happen for Ireland is unclear, though it might be reasonable to expect that, with the relatively low population concentration of southern Ireland, it will not get much of a look-in with this technological application. However understandable this is from a commercial point of view, it is still a shame that this technology has not been taken up more widely.
As a scientific exercise of information gathering, the NEXTMap survey has the potential to further the bank of knowledge of the countryside, geography and urbanism. It is always exciting to see the great potential that can often be realised through commercial enterprises that come up with these ingenious technological advances, but it is sometimes disappointing to realise how much better, how much more equitably distributed, and how universal that technology would be if commercial considerations were not uppermost in the equation.
However, there are no plans at the moment for a new brand called BangladeshMap to assist in the alleviation of that country's significantly more lethal floodplain topography.
For more information, contact 01252 849 450 or visit www. getmapping. com