2006 USGS/NPS/NASA Experimental Advanced Airborne Research Lidar (EAARL): Jean Lafitte National Historical Park and Preserve

A first surface/bare earth elevation map (also known as a Digital Elevation Model, or DEM) of the Jean Lafitte National Historical Park and Preserve

in Louisiana was produced from remotely sensed, geographically referenced elevation measurements cooperatively by the U.S. Geological Survey (USGS),

the National Park Service (NPS), 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 easily surveyed 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.

Original contact information:

Contact Name: Amar Nayegandhi

Contact Org: Jacobs Technology, U.S. Geological Survey, FISC, St. Petersburg, FL

Title: Computer Scientist

Phone: 727-803-8747 (x3026)

Email: anayegandhi@usgs.gov

The purpose of this project was to produce a highly detailed and accurate first surface/bare earth elevation map of the Jean Lafitte National

Historical Park and Preserve in Louisiana for natural resource managers and research scientists.

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Raw Lidar data are not in a format that is generally usable by Park Service resource managers and scientists for scientific analysis. 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 Airborne 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 GEOID03 model). Each file contains data

located in a 2-km by 2-km tile, where the upper-left bound can be assessed quickly through the file name. The first 3 numbers in the file name

represent the left-most UTM easting coordinate (e###000) in meters, the next 4 numbers represent the top-most UTM northing coordinate (n####000) in

meters, and the last 2 numbers (##) represent the UTM zone in which the tile is located (for example, fs_e123_n4567_15).

The development of custom software for creating these data products has been supported by the U.S. Geological Survey CMG Program's Decision Support

for Coastal Parks, Sanctuaries, and Preserves Project. Processed data products are used by the U.S. Geological Survey 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.

A footprint of the data may be viewed in Google Earth at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/578/supplemental/2006_USGS_NPS_NASA_EAARL_Lidar_Jean_Lafitte_Louisiana.kmz

LAS v 1.2

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 1-ns time-resolved return intensity waveform (digital counts). Z value is referenced to

orthometric elevations derived from National Geodetic Survey Geoid Model, GEOID03.

Any conclusions drawn from the analysis of this information are not the responsibility of the Office for Coastal Management

or its partners.

This data can be obtained on-line at the following URL: https://coast.noaa.gov/dataviewer;

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Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent

actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations. The U.S. Geological

Survey, National Park Service, and National Aeronautics and Space Administration request to be acknowledged as originators of this data in future

products or derivative research.

Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; ESRI ArcMap 9.2.2.1350

The expected accuracy of the measured variables is as follows: attitude within 0.07 degree, 3 cm nominal laser ranging accuracy, and vertical

elevation accuracy of +/-15 cm for the topographic surface. Quality checks are built into the data-processing software.

Raw elevation measurements have been determined to be within 1 meter horizontal accuracy.

Elevations of the DEM are vertically consistent with the point elevation data, +/-15 cm.

Several regions of the dataset are labeled as "No Data", which corresponds to a cell value of -32767 m in the GeoTIFF file. These "No Data" areas are

a result of the survey not covering a particular region, optical water depth of greater than 1.5 Secchi disc depths, or the manual removal of lidar

processing artifacts.

Each file contains data located in a 2-kilometer by 2-kilometer tile, where the upper-left bound can be assessed quickly through the filename.

The first 3 numbers in the filename represent the left-most UTM easting coordinate (e###000) in meters, the next 4 numbers represent the top-most UTM

northing coordinate (n####000) in meters, and the last 2 numbers (##) represent the UTM zone in which the tile is located (ex. fs_e123_n4567_16).