One of the most significant uses of 3-D scanning in the years to come will not be by humans at all but by autonomous vehicles. Cars are already learning to drive themselves, by way of scanner-assisted braking, pedestrian-detection sensors, parallel-parking support, lane-departure warnings and other complex driver-assistance systems, and full autonomy is on the horizon. Google’s self-driving cars have logged more than a million miles on public roads; Elon Musk of Tesla says he’ll probably have a driverless passenger car by 2018; and the Institute of Electrical and Electronics Engineers says autonomous vehicles ‘‘will account for up to 75 percent of cars on the road by the year 2040.’’ Driver-controlled cars remade the world in the last century, and there is good reason to expect that driverless cars will remake it again in the century to come: Gridlock could become extinct as cars steer themselves along a cooperatively evolving lacework of alternative routes, like information traversing the Internet. With competing robot cars just a smartphone tap away, the need for street parking could evaporate, freeing up as much as a third of the entire surface area of some major American cities. And as distracted drivers are replaced by unblinking machines, roads could become safer for everyone.
But all of that depends on cars being able to navigate the built environment. The cars now being tested by Google, BMW, Ford and others all see by way of a particular kind of scanning system called lidar (a portmanteau of ‘‘light’’ and ‘‘radar’’). A lidar scanner sends out tiny bursts of illumination invisible to the human eye, almost a million every second, that bounce off every building, object and person in the area. This undetectable machine-flicker is ‘‘capturing’’ extremely detailed, millimeter-scale measurements of the surrounding environment, far more accurate than anything achievable by the human eye. Capturing resembles photography, but it operates volumetrically, producing a complete three-dimensional model of a scene. The extreme accuracy of lidar lends it an air of infallible objectivity; a clean scan of a stationary structure can be so precise that nonprofit organizations like CyArk have been using lidar as a tool for archaeological preservation in conflict zones, hoping to capture at-risk sites of historical significance before they are destroyed. […]