2004 USGS/NASA Experimental Advanced Airborne Research Lidar (EAARL): Northern Gulf
of Mexico, Post-Hurricane Ivan
This kmz file shows the extent of coverage for the 2004 USGS Northern Gulf Post-Hurricane
Ivan lidar data set.
ASCII xyz point cloud data were produced from remotely-sensed, geographically-referenced
elevation measurements in cooperation with the U.S. Geological Survey (USGS) and National
Air 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 kHz or higher results in an extremely dense spatial elevation data set. Over 100
kilometers of coastline can be easily surveyed within a 3 to 4 hour mission time period.
When subsequent elevation maps for an area are analyzed, they provide a useful tool
to make management decisions regarding land development.
Cite this dataset when used as a source.
|Search and Download
|| Distributor information not available
| Point of Contact
Documentation links not available.
- National Aeronautics and Space Administration (NASA)
|Data Presentation Form:
|| Digital image
|Dataset Progress Status
|Data Update Frequency:
|| As needed
||Raw lidar data is not in a format that is generally usable by resource managers and
scientists. Converting dense Lidar elevation data into a readily usable format without
loss of essential information requires specialized processing. The U. S. Geological
Survey's Coastal and Marine Geology (CMG) Program has developed custom software to
convert raw lidar data into a GIS compatible map product to be provided to GIS specialists,
managers, and scientists. The primary tool used in the conversion process is Advanced
Lidar Processing System (ALPS), a multi-tiered processing system developed by a USGS/NASA
collaborative project. Specialized processing algorithms are used to convert raw waveform
Lidar data acquired by the EAARL to georeferenced spot (x,y,z) returns for "first
surface" and "bare earth" topography. These data are then converted to the North American
Datum of 1983 and the North American Vertical Datum of 1988 (using the Geoid 03 model).
The files are in the Quarter Quad tiling format and the exact tile location is contained
in the filename at n88_########_mf_be where ####### is the Quarter Quad tile ID. The
development of custom software for creating these data products has been supported
by the USGS CMG Program's 'Decision Support for Coastal Parks, Sanctuaries, and Preserves'
project. Processed data products are used by the USGS CMG Program's 'National Assessments
of Coastal Change Hazards Project' to quantify the vulnerability of shorelines to
coastal change hazards such as severe storms, sea-level rise, and shoreline erosion
and retreat. LAS The variables measured by EAARL are: distance between aircraft and
GPS satellites (m), attitude information (roll, pitch, heading in degrees), scan angle
(degrees), second of the epoch (sec), and 1ns time-resolved return intensity waveform
(digital counts). Z value is referenced to orthometric elevations derived from National
Geodetic Survey Geoid Model, Geoid03.
||The ASCII elevation data can be used to create raster Digital Elevation Models (DEMs).
The purpose of this project is to produce highly detailed and accurate digital elevation
maps of the post Hurricane Ivan data for use as a management tool and to make this
data available to natural resource managers and research scientists.
|| Unknown to Unknown
|Spatial Reference System:
|Spatial Bounding Box Coordinates:
|Spatial Coverage Map:
- USGS remote sensing
- Experimental Advanced Airborne Research Lidar
- Digital Elevation Model
- elevation change
- laser altimetry
- derived surface
- resource management
- Advanced Lidar Processing System
| Use Constraints
|| No constraint information available
|| Fee information not available.
|| Lineage statement not available.
- Jacobs Technology, U. S. Geological Survey, FISC St. Petersburg
| Processing Steps
- The data are collected using a Cessna 310 aircraft. The NASA Experimental Advanced
Airborne Research Lidar (EAARL) laser scanner collects the data using a green (532nm)
raster scanning laser, while a digital camera acquires a visual record of the flight.
The data are stored on hard drives and archived at the U. S. Geological Survey, FISC
St. Petersburg office and the NASA office at Wallops Flight Facility. The navigational
data are processed at Wallops Flight Facility. The navigational and raw data are then
downloaded into the Advanced Lidar Processing System (ALPS). Data are converted from
units of time to x,y,z points for elevation. The derived surface data can then be
converted into raster data (geotiffs).
- The NOAA Coastal Services Center received the data in LAS format. The files contained
Lidar elevation and intensity measurements. The data were projected in UTM coordinates
(NAD83; Zone 16N) and referenced to the North American Vertical Datum of 1988 (NAVD88)
using the Geoid03 model. The following processes were performed to make the data available
within the Digital Coast: 1. The data were converted from UTM (NAD83; Zone 17N) to
geographic coordinates (NAD83). 2. The data were converted from NAVD88 (orthometric)
heights to GRS80 (ellipsoidal) heights using the Geoid03 model. 3. The data were reclassified
to reflect the ASPRS LAS classifications (1 - unclassified, 2 - bare earth). 4. The
LAS data were sorted by latitude and the headers were updated. 5. The data were converted
to LAZ format.
- The NOAA National Geophysical Data Center (NGDC) received lidar data files via ftp
transfer from the NOAA Coastal Services Center. The data are currently
being served via NOAA CSC Digital Coast at http://www.csc.noaa.gov/digitalcoast/.
The data can be used to re-populate the system. The data are archived in LAS or LAZ
The LAS format is an industry standard for LiDAR data developed by the American Society
of Photogrammetry and Remote Sensing (ASPRS); LAZ is a loseless compressed version
LAS developed by Martin Isenburg (http://www.laszip.org/). The data are exclusively
in geographic coordinates (either NAD83 or ITRF94). The data are referenced vertically
the ellipsoid (either GRS80 or ITRF94), allowing for the ability to apply the most
up to date geoid model when transforming to orthometric heights.
Metadata Last Modified: 2013-01-22
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