2007 USGS/NASA Experimental Advanced Airborne Research Lidar (EAARL): Fire Island National Seashore, NY and Sandy Hook, NJ

ASCII xyz point cloud data were produced from remotely sensed, geographically referenced elevation measurements cooperatively

by the U.S. Geological Survey (USGS) and National Aeronautics and Space Administration (NASA). Elevation measurements were

collected over the barrier island areas of Nassau and Suffolk Counties (Fire Island Natational Seashore)in New York and Monmouth County

(Sandy Hook) in New Jersey, 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, U.S. Geological Survey, FISC

Title: Computer Scientist

Phone: 727-803-8747 (x3026)

Email: anayegandhi@usgs.gov

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 northeast coastal barrier islands for use as a management tool and to

make these data available to natural resource managers and research scientists.

10748

Raw Lidar data are 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.

Binary lidar data file for xyz data points.

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.

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 herein 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 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 ASCII 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.

The files are in the Quarter-Quad tiling format and the exact tile location is contained in the filename at n88_########_mf_be/fs

where ####### is the Quarter-Quad tile ID.

See QQ_naming_convention.doc in the 'extras' directory.