| 2004 USGS/NASA Experimental Advanced Airborne Research Lidar (EAARL): Western Florida,
Post-Hurricane Charley (Seamless Topo-Bathy) |
| A seamless (bare-earth and submerged) elevation map (also known as a Digital Elevation
Model, or DEM) of a portion of western Florida, post-Hurricane Charley, was produced
from remotely sensed, geographically referenced elevation measurements cooperatively
by the U.S. Geological Survey (USGS) and the National Aeronautics and Space Administration
(NASA). Elevation measurements were collected over the area using the NASA Experimental
Advanced Airborne Research Lidar (EAARL), a pulsed laser ranging system mounted onboard
an aircraft to measure ground elevation, vegetation canopy, and coastal topography.
The system uses high-frequency laser beams directed at the Earth’s surface through
an opening in the bottom of the aircraft’s fuselage. The laser system records the
time difference between emission of the laser beam and the reception of the reflected
laser signal in the aircraft. The plane travels over the target area at approximately
50 meters per second at an elevation of approximately 300 meters. The EAARL, developed
by NASA at Wallops Flight Facility in Virginia, measures ground elevation with a vertical
resolution of +/-15 centimeters. A sampling rate of 3 kilohertz or higher results
in an extremely dense spatial elevation dataset. Over 100 kilometers of coastline
can be surveyed easily within a 3- to 4-hour mission. When subsequent elevation maps
for an area are analyzed, they provide a useful tool to make management decisions
regarding land development.
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