Software stitches a high-resolution 3-D model by processing overlapping photos.
Drones don’t have very reliable GPS fixes by comparison, and can’t carry large sensors or cameras. But they are cheap, and Pix4D’s software can build highly accurate models by comparing many different overlapping photos, says Strecha. In fact, using lidar would have been impossible with the Rio statue, Strecha says, because of its size, shape, and location.
Other projects have also been weaving 3-D models from drone photos. Researchers led by Horst Bischof, a professor at the Technical University of Graz, Austria, are developing software that extracts information from such images. For example, for a company that restores old buildings, the researchers made a version of the software that calculates measurements necessary for producing custom-fit thermal insulation.
With the image processing more or less a solved problem, the ambitions of drone scanning will depend more on how well drones can be controlled or coӧrdinated in challenging conditions like the winds around Rio’s Christ, or to cover larger areas, says Carl Salvaggio, a professor at Rochester Institute of Technology’s Center for Imaging Science. “Drones are good for small-scale projects but traditional aircraft offer the time in the air to collect whole cities,” he says. “Perhaps when there are ‘armies’ of drones in the air, we will see a different landscape emerge.”