Sherlock Holmes favoured the magnifying glass. Today's European Union fraud detectives prefer something more powerful - satellites, which will soon be capable of identifying objects just one yard square from 500 miles up in the sky.
The satellite has come into its own with the creation of the EU set-aside scheme. It combats over-production by subsidising farmers who take arable land out of use. The satellite shows precisely what crops are being grown and whether farmers have told the truth in applications for EU aid.
Since the EU allows member states discretion to permit some crops (such as lentils and chick peas) to be grown on set-aside land, the technology has to be sophisticated enough to distinguish between different uses.
According to Paul Kidney of the Dublin computer company ERA Maptech, which analyses satellite data on Irish farming for the EU, this is possible because each crop sends back a distinct digital image. "Light falls on crops and reflects back in particular light patterns. This means there is a 'reflection signature code' in the satellite signal returned to the tracking station."
The EU's Satellite Pour Observation de la Terre (SPOT) produces different "codes" for grass, barley, spring wheat and winter barley, among other commonly grown crops. These are displayed in different colours in maps sent on to the EU and the national government.
Assembled in millions of band widths of reflected light, the pictures build up to form a minutely-detailed map. The EU is complementing the satellite data with a massive computerised inventory in which every field has its own number.
The technology is sufficiently advanced to enable differentiation between old, dying trees in a copse in a set-aside area, and a plantation of healthy new saplings.
EU specialists are expected to upgrade the degree of resolution possible next year, enhancing the smallest definable object from the present 10 yards square to one. (Cold War spy satellites only offered five yard resolution).
In policing terms, set-aside crop surveillance gives EU inspectors fool- proof data before they ever cross the farm gate. "We check the area of the field planted to see if the size or acreage (stated by the farmer) are correct," says Mr Kidney.
The crop shown is then checked to see if what is visible corresponds with what the farmer has declared. A third precaution checks if anyone else has claimed for the same field, a task simplified by the new numbering system.
To discourage fraud, the location and scale of lands chosen for investigation remains a closely guarded secret. EU sources say the percentage of fraudulent claims discovered since the scheme was set up in 1991 is under five per cent.
Constant scanning over weeks and months by a satellite orbiting the Earth every 90 minutes means passing obstructions such as heavy cloud banks cannot prevent surveillance. Periods of crop growth provide clear reflection codes, complementing other distinct images obtained during ploughing, seeding and harvest periods.
Even during limited visibility, satellite computers can be programmed to look at an angle under cloud banks. For example, they can observe Irish landscapes when passing over Liverpool. Analysis may be refined by using combinations of data from radar and optical satellites.
The development of digital satellite images requiring no film means sections can now be more easily "stitched" together for large-scale analysis. Satellites provide data on a visible "footprint" up to 60sq km.
The precision of the images has settled some heated disputes. When a sizeable number of Irish grain producers allegedly understated their output in tax declarations, there was general alarm when this information was used to set new lower output quotas.
With even those who had declared correct yields facing lower EU output ceilings, satellite data was then summoned to demonstrate definitively the actual acreage cultivated so a more realistic quota could be set. In countries such as Italy better climatic conditions allow closer-range aerial photography to be used in crop studies.Reuse content