MUMBAI, Feb. 19 -- For nine months last year, the 600 acres of Dharavi were mapped and surveyed using drones. The images from these drone surveys will now be used as proof to eliminate "illegal" structures, and Dharavikars in the latter will not qualify for redevelopment benefits. This is the first time that the authorities are making it clear who qualifies as illegal and stands to lose everything after the ongoing physical door-to-door survey is complete....