London: US technology giants Google and Apple are racing to produce aerial maps so detailed they can show up objects just four inches wide, Daily Mail reported Monday.
But campaigners say the technology is a sinister development that brings the surveillance society a step closer.
Google admits it has already sent planes over cities while Apple has acquired a firm using spy-in-the-sky technology that has been tested on at least 20 locations, including London.
Apple's military-grade cameras are understood to be so powerful they could potentially see into homes through skylights and windows.
The technology is similar to that used by intelligence agencies in identifying terrorist targets in Afghanistan, the newspaper said.
Apple has previously used Google for its mapping services but last year it emerged it had bought C3 Technologies, a 3D mapping company that uses technology developed by Saab AB, the aerospace and defence company.
There are already 3D maps available online for most big city centres, but the images are often low resolution.