Second site God's-eye view of your backyard

GIVEN the chance of a god's-eye view, what would you most like to see? A whorl of cloud above an ocean or the Great Wall of China? These images are available if you trail around the ample supply of websites devoted to the weather, or the smaller number that are interested in satellite pictures of the Earth for their own sake. But for most of us, there's no place like home. What we'd really like to see would be a god's-eye view of our own little acre.

For many people, most of them in the United States, this wish can come true thanks to Microsoft's TerraServer. Viewers can select a place by name or map coordinates, and if the location is included in any image held in the archives, a black and white satellite image appears on the screen. Since you can only see objects larger than 16 metres, you will (probably) not be able to see your house from there, but a zoom button takes the view in close enough to reveal objects 1.5 metres in size.

To make much of that level of detail, however, viewers will probably need to order either a digital image or an old-fashioned Kodak print of the image. Prices start at $7.95, but most of the sample charges in the buying guide are well into double figures. This service counters three great technological myths of our time: that you can find everything on the Web; that you can then get hold of it for nothing; and that you could read car licence plates off spy satellite pictures (assuming the car to be standing on its end).

Many of these actually are spy satellite pictures. Some come from the US Geographical Sur-vey, but the other source is SPIN-2, a joint venture between a Russian and an American firm to market images gathered by Russian military satellites. The Russian partner rejoices in the magnificently retro name of Sovinformsputnik which harks back to the glory days of Soviet space exploits, and Sputnik, the very first brand in space.

The TerraServer pages are studded with corporate logos, and pulsate with adverts, suggesting that there is money in it for somebody. It doesn't look as though much of the revenue derives from actually selling pictures, though - in a recent chart of the most commonly requested sites, the town of Waterbury, Connecticut, which has a population of just 110,000, came 10th.

A disproportionate amount of traffic comes from the UK, in spite of the fact that the map showing current coverage is as patchy as a map of Liberal Democrat constituencies. The central belt of Scotland is featured, as are south Wales, north Wales and adjoining strips of England, a swathe of the north-east coast up from the Wash, London, and a couple of blobs in the south-east. To fill out the picture, TerraServer has formed a partnership with a British venture called UK Perspectives, which will provide aerial colour images of the whole country, down to a resolution of a quarter of a metre.

This project is a spin off from the Millennium Aerial Photo-graphic Survey (backed by the National Remote Sensing Centre), which promises a fine- grained digital map of Britain so that professionals and home PC users alike will be able to explore the country in three dimensions.

There is little evidence that the rest of the world is about to be offered such a personal service. The website run by Spot Image, a venture led by CNES, the French space agency, breezily offers its unclassified images to the world's militaries, suggesting that they could come in handy for "rapid response in fast-breaking situations". It also highlights one of its principal applications, scanning EU farmland in an attempt to curb fraudulent subsidy claims.

You can visit www.poptel.org.uk/secondsite for links to pages mentioned or contact Marek Kohn on secondsite@poptel.net

IE COVERED BY SATELLITE at the high scales IE RSOLUTIONneeded for modern economic development WHY NEEDD FOR DEVMT, and many of the charts WHAT CHARTS that do exist are unreliable.