Aerial imagery and roof measurement is a service that photographs whole cities from aircraft, closely enough to measure a single roof, and sells those measurements to insurers and roofing companies, with any damage detected automatically. The business is mainly in the United States. There, most houses have sloping roofs covered with asphalt shingles, and hailstorms, hurricanes and tornadoes damage a great many roofs every year.
How does it work? Small aircraft carry several cameras. One points straight down, and others point forward, backward and to the sides at an angle. The aircraft fly over each city in planned lines, and fly again over areas hit by a major storm. Each pixel of the photos covers a few centimetres of ground. Software matches the views from different angles and builds a 3D model of each roof. From the model, it measures each sloping face of the roof: its area and its pitch, which is how steep it is. It also measures the length of each ridge, valley and edge. Computer vision models, trained on many labelled photos, find damage such as missing shingles, fallen trees and tarpaulins laid over holes. This is a use of geospatial AI.
Imagine a hailstorm passing over the suburbs of Dallas, in Texas, one evening in May. Over the next two days, an insurer receives 6,000 claims from home owners. In the past, an employee called an adjuster had to visit each house and climb onto the roof with a tape measure. Now the insurer orders the photos flown over the storm area after the hail. For each claim, the report shows the roof's area, for example 2,800 square feet, its pitch and the damage the model has found. The report also compares the roof with photos taken before the storm, so that old damage is not paid for as new. Claims with clear damage are approved without a visit. The unclear ones still get an inspection.
Roofing companies use the same report to quote for a new roof without climbing onto the old one. The measurements go into their construction estimating software, which counts the materials and labour. They also go into field service management, which sends the crew out with the right amount of material. Insurers also use the age and condition of each roof to set the price of a new policy. That information is part of property risk data.
Why is this business so small in India? Most Indian houses have flat concrete roofs, which storms damage less often, and fewer homes are insured. Similar aerial and satellite images are used in India mainly for other jobs, such as planning rooftop solar panels with solar design software. Drones do similar work at a smaller scale, through drone surveying.