AI software has detected more than 20,000 secret private swimming pools in aerial photography, helping French tax officials bag about €10 million (£ 8.6 million) in extra property levies. Home improvements, such as the addition of a loft or a pool, can boost the value of a property and increase the taxes homeowners pay in the Euro nation. A 30-square-metre pool, for example, could set you back an extra €200 (£170) a year. People are required to declare these kinds of constructions, though some keep quiet to avoid having to fork out more money. In a bid to catch tax dodgers out, nine departments working under France's tax office tested out machine-learning software to automatically find undeclared swimming pools from overhead photos.