Sixty feet up above the suburb of Saligramam, a hovering drone generated over 1,500 images of the locality one day recently. It was one of six such sophisticated machines that have been flying over the city over the past five months, collecting a wealth of detailed images. This is a unique project of the Greater Chennai Municipal Corporation (GCMC) under way.
Chennai’s pioneering drone mapping project is expected to have a significant impact on curbing encroachment of municipal property, penalising land-grabbing, and preventing tax evasion by owners who have under-assessed their property tax liability. It will also help improve disaster management plans and mitigate flooding.
“This is a great civic project,” says a technician on the team.
Images have so far been captured from 12 wards of the Madhavaram zone, 15 wards of the Tondiarpet zone, 15 wards of the Thiru-Vi-Ka Nagar zone, 15 wards of the Ambattur zone, 15 wards of Anna Nagar zone, and a part of Royapuram zone covering seven wards.
Personnel associated with the project say the original proposal recommended satellite imagery. “Later they opted for a drone survey. The technology is advanced,” says the technician.
Crucial phase
Starting April, the drones started another crucial phase of surveying civic infrastructure.
This is a challenging part because of concerns related to air safety and national security.
Work in the ‘funnel areas’ along flight paths at the Chennai International Airport, for example, is carried out for less than an hour a day.
Originally launched with a 120-day deadline, the project has slowed down into its 5th month.
“All our operations are based on the directions of the airport authorities. We have posted one engineer in the Air Traffic Control to communicate in real time,” says R. Lalitha, Chennai Corporation Deputy Commissioner-Revenue and Finance, who is the head of operations.
Additionally,day-to-day clearance is sought from Defence and Naval officials.
Another type of drone with four propellers is used to survey the ‘funnel areas’ as it can take off and land within the shortest possible time after air safety clearance, officials said. But the drones with four propellers can capture fewer images, slowing the project.
“Our engineers are working hard to prove that the drone survey is safe, before getting permission to continue the survey in the area covering 47.75 sq. km. within a radius 5 km from the airport,” says Srinivasan, a GIS expert with the Chennai Corporation.
Other issues are taken into consideration. “A hexacopter drone (with six propellers) has the capacity to capture images from a height of 200 metres. But we are recording five images a second from a maximum height of 60 m since Defence officials imposed certain restrictions for strategic reasons,” said a technician.
A few weeks ago, operations were suspended for three days during Prime Minister Narendra Modi’s visit.
Vetted images
A team will visit Delhi next month to collect a first batch of vetted images, and hand over a second set of images at that time, to the Defence Ministry. The Ministry is expected to account for sensitive locations and give the images back to the Chennai Corporation.
As computerisation of land records is under way, civic officials are waiting for the vetted digital images to overlay them on the cadastral maps that represent all registered plots of land in the city.
“Encroachments will be identified by overlaying the cadastral map with the digital images,” says an official.
“We will even be able to check changes in the meandering flow of the Cooum, the Adyar and the Kosasthalaiyar rivers.”
