2008 USGS/NPS/NASA Experimental Advanced Airborne Research Lidar (EAARL): Pearl River Delta, LA and MS

A bare earth elevation map (also known as a Digital Elevation Model or DEM) of the Pearl River Delta in Louisiana and Mississippi

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). This data set provides

those bare earth elevation measurements in portions of the following parishes/counties: Orleans and St. Tammany in Louisiana and

Hancock in Mississippi.

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 time period. 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, contracted to USGS

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 bare earth digital elevation map of the Pearl River Delta

in Louisiana and Mississippi for use as a management tool and to make these data available to natural resource managers and research

scientists.

10753

Raw Lidar data are not in a format that is generally usable by 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 Geoid 03 model). Each file contains data located in a 2 km by 2 km tile, where the

upper left bound can be quickly assessed through the file name. 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. be_e123_n4567_18).

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 this data set may be viewed in Google Earth at:

https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/540/supplemental/2008_USGS_NPS_NASA_EAARL_Lidar_Pearl_River.kmz

The LAS grid is encoded with a 1 meter resolution.

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.

Although these data have been processed successfully on a computer system at the U.S. Geological Survey,

no warranty expressed or implied is made regarding the display or utility of the data on any other system, nor shall the act of

distribution imply any such warranty. The U.S. Geological Survey shall not be held liable for improper or incorrect use of the

data described and (or) contained herein. Reference herin to any specific commercial product, process, or service by trade name,

trademark, manufacturer, or otherwise does not constitute or imply its endorsement, recommendation, or favoring by the United

States Government or any agency thereof.

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

its partners.

Unclassified

None

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

None

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.

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

The expected accuracy of the measured variables is as follows: attitude within 0.07 degree, 3 cm nominal 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 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 LAS 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 km by 2 km tile, where the upper left bound can be quickly assessed through the file name.

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. be_e123_n4567_18).