Lidar accelerates hurricane recovery in the Carolinas

Hurricane Florence's slow trot over North and South Carolina in September led to inundating rain, record storm surges, and another major disaster for the Federal Emergency Management Agency (FEMA) to contend with. Facing damage over hundreds of square miles, FEMA again called upon MIT Lincoln Laboratory to use their state-of-the-art lidar system to image the destruction in the region.

Installed onto an airplane and flown nightly over a disaster site, lidar (which stands for light detection and ranging) sends out pulses of laser light that bounce off the land and structures below and are collected again by the instrument. The timing of each light pulse's return to the instrument is used to build what researchers call a "point-cloud map," a high-resolution 3-D model of the scanned area that depicts the heights of structures and landscape features. Laboratory analysts can then process this point-cloud data to glean information that helps FEMA focus their recovery efforts—for example, by estimating the number of collapsed houses in an area, the volume of debris piles, and the reach of flood waters.

Yet quickly sending the nearly two terabytes of data from a single night's scan, or sortie, to the Laboratory for processing is a challenge. After a storm, local internet connections may be gone or spotty. When the Laboratory used this same lidar platform after Hurricane Maria in Puerto Rico, downed networks meant having to physically ship a hard drive back to Massachusetts—a more than two-day delay in getting the data into analysts' hands. When the team started the campaign in the Carolinas in mid-September, they faced the same obstacle.

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