Sea Floor Mapping Lidar

Team at Georgia Tech Has Now Developed a Cost-effective New System that They Claim Could Lead to Much Smaller, More Efficient Bathymetric Lidars, Capable of Being Carried by a UAV Reaserch

When an organization sets out to map the sea floor, it will typically use a device known as a bathymetric lidar (Light Detection and Ranging) unit. These are large and can weigh almost 600 lb (272 kg), so they're mounted on crewed aircraft that fly over the area to be mapped. Led by Dr. Grady Tuell, a team at Georgia Tech has now developed a cost-effective new system that they claim could lead to much smaller, more efficient bathymetric lidars, capable of being carried by a UAV.

On a regular bathymetric lidar, laser light pulses are emitted down through the water to the sea bed, then reflected back up to the device. By analyzing the amount of time that elapses between a pulse being emitted and its reflection being received, it's possible to gauge the depth at that particular point. By combining a multitude of these readings, a three-dimensional point cloud map of the sea floor is subsequently created. It takes time to analyze the signals, however, as both the refractive index and the turbidity of the water must be accounted for.

In the Georgia Tech system, the accuracy of each measurement point is checked much more quickly and efficiently. It utilizes a computing technique known as total propagated uncertainty (TPU), which incorporates "statistics, calculus and linear algebra." Additionally, its hardware consists of field programmable gate arrays (electronic circuits that are configured by the user for the specified task), plus central-processing and graphics-processing units.

As a result, it's able to process approximately 37 million points per second - by contrast, some traditional bathymetric lidars only manage speeds of 1,000 per second.

Source: Gizmag

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