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OCM Partners, 2023: 2009 USGS/NPS Experimental Advanced Airborne Research Lidar (EAARL): Cape Hatteras National Seashore - Post-Nor'easter Ida,

Item Identification

Title: 2009 USGS/NPS Experimental Advanced Airborne Research Lidar (EAARL): Cape Hatteras National Seashore - Post-Nor'easter Ida
Short Name: usgs2009_nc_post_ida_m1071_metadata
Status: Completed
Publication Date: 2011

This is a bare-earth data lidar data set that was collected on November 27, 29 and December 1, 2009 along the shoreline of the Cape

Hatteras National Seashore in Dare and Hyde Counties in North Carolina, after Nor'easter Ida.

Binary point-cloud data were produced from remotely sensed, geographically referenced elevation measurements cooperatively by the U.S. Geological

Survey (USGS) and the National Park Service (NPS). Elevation measurements were collected over the area using the 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, resulting in a laser swath of

approximately 240 meters with an average point spacing of 2-3 meters. The EAARL, developed originally 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, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL

Title: Remote Sensing Specialist/Project Manager

Phone: 727 803-8747 (x3026)



The purpose of this project was to produce highly detailed and accurate digital elevation maps of a portion of the Cape Hatteras National Seashore

in Dare and Hyde Counties in North Carolina, post-Nor'Ida (November 2009 nor'easter), for use as a management tool and to make these data available

to natural-resource managers and research scientists.



Supplemental Information:

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 Program (CMGP) 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. The terms first surface and

bare earth refer to the digital elevation data of the terrain, but while first-surface data includes vegetation, buildings, and other man-made

structures, bare-earth data does not. The zero crossing of the second derivative (that is, detection of local maxima) is used to detect the first

return, resulting in "first surface" topography, while the trailing edge algorithm (that is, the algorithm searches for the location prior to the

last return where direction changes along the trailing edge) is used to detect the range to the last return or "bare earth" (the first and last

returns being the first and last significant measurable portion of the return pulse). Statistical filtering, known as the Random Consensus

Filter (RCF), is used to remove false bottom returns and other outliers from the EAARL topography data. The filter uses a grid of non-overlapping

square cells (buffer) of user-defined size overlaid onto the original point cloud. The user also defines the vertical tolerance (vertical width)

based on the topographic complexity and point sampling density of the data. The maximum allowable elevation range within a cell is established by

this vertical tolerance. An iterative process searches for the maximum concentration of points within the vertical tolerance, and removes those

points outside of the tolerance (Nayegandhi and others, 2009). These data are then converted to the North American Datum of 1983 and the North

American Vertical Datum of 1988 (using the GEOID09 model).

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 Science and Management 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:


Theme Keywords

Thesaurus Keyword
ISO 19115 Topic Category

Temporal Keywords

Thesaurus Keyword
None 2009
None Post-Nor'Ida

Physical Location

Organization: Office for Coastal Management
City: Charleston
State/Province: SC

Data Set Information

Data Set Scope Code: Data Set
Maintenance Frequency: None Planned
Entity Attribute Overview:

The input parameters for the random consensus filter (RCF) were: grid cell size (buffer) = 6 meters x 6 meters; vertical tolerance

(vertical width) = 500 centimeters.

Entity Attribute Detail Citation:

Distribution Liability:

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, or for general or scientific purposes, nor shall the act of distribution constitute

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.

Neither the U.S. Government, the Department of the Interior, nor the USGS, nor any of their employees, contractors, or subcontractors, make any warranty,

expressed or implied, nor assume any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus,

product, or process disclosed, nor represent that its use would not infringe on privately owned rights.

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

Data Set Credit: The U.S. Geological Survey and the National Park Service request to be acknowledged as originators of this data in future products or derivative research. Acknowledgment of the U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, as a data source would be appreciated in products developed from these data, and such acknowledgment as is standard for citation and legal practices for data source is expected. Sharing of new data layers developed directly from these data would also be appreciated by the U.S. Geological Survey staff. Users should be aware that comparisons with other datasets for the same area from other time periods may be inaccurate due to inconsistencies resulting from changes in photointerpretation, mapping conventions, and digital processes over time. These data are not legal documents and are not to be used as such.

Support Roles

Data Steward

CC ID: 690876
Date Effective From: 2011
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202


CC ID: 690878
Date Effective From: 2011
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202

Metadata Contact

CC ID: 690879
Date Effective From: 2011
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202

Point of Contact

CC ID: 690877
Date Effective From: 2011
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address:
Phone: (843) 740-1202


Currentness Reference: Ground Condition

Extent Group 1

Extent Group 1 / Geographic Area 1

CC ID: 1132415
W° Bound: -76.02462
E° Bound: -75.455316
N° Bound: 35.963517
S° Bound: 35.064837

Extent Group 1 / Time Frame 1

CC ID: 1132412
Time Frame Type: Discrete
Start: 2009-11-27

Extent Group 1 / Time Frame 2

CC ID: 1132413
Time Frame Type: Discrete
Start: 2009-11-29

Extent Group 1 / Time Frame 3

CC ID: 1132414
Time Frame Type: Discrete
Start: 2009-12-01

Spatial Information

Spatial Representation

Representations Used

Vector: Yes

Access Information

Security Class: Unclassified
Security Classification System:


Security Handling Description:


Data Access Procedure:

This data can be obtained on-line at the following URL:;

Data Access Constraints:


Data Use Constraints:

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


Distribution Information

Distribution 1

CC ID: 743083
Download URL:
File Name: Customized Download

Create custom data files by choosing data area, product type, map projection, file format, datum, etc.

Distribution 2

CC ID: 743084
Download URL:
File Name: Bulk Download

Simple download of data files.



CC ID: 743086
URL Type:
Online Resource


CC ID: 743087
URL Type:
Online Resource


CC ID: 743088
Name: Browse Graphic
URL Type:
Browse Graphic
File Resource Format: kmz

This kmz file shows the lidar footprint for the 2009 USGS/NPS Lidar for Cape Hatteras National Seashore.

Activity Log

Activity Log 1

CC ID: 690905
Activity Date/Time: 2016-05-23

Date that the source FGDC record was last modified.

Activity Log 2

CC ID: 690904
Activity Date/Time: 2017-11-14

Converted from FGDC Content Standards for Digital Geospatial Metadata (version FGDC-STD-001-1998) using '' script. Contact Tyler Christensen (NOS) for details.

Activity Log 3

CC ID: 718715
Activity Date/Time: 2018-02-08

Partial upload of Positional Accuracy fields only.

Activity Log 4

CC ID: 743085
Activity Date/Time: 2018-03-13

Partial upload to move data access links to Distribution Info.

Technical Environment


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

Data Quality


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

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

Horizontal Positional Accuracy:

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

Vertical Positional Accuracy:

Typical vertical elevation accuracies for these data are consistent with the point elevation data, +/-15 centimeters. However, a ground-control

survey is not conducted simultaneously with every lidar survey. Vertical accuracies may vary based on the type of terrain and the accuracy of the

GPS and aircraft-attitude measurements.

Completeness Report:

These point-cloud data may appear sparse or nonexistent, which is a result of removal from manual editing or lack of survey coverage.

Conceptual Consistency:

The original files as received by NOAA OCM, contained data located in a 10-kilometer by 10-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 (for example, fs_e123_n4567_18).


Process Steps

Process Step 1

CC ID: 1132408

The data were collected using a Pilatus PC-6 aircraft. The Experimental Advanced Airborne Research Lidar (EAARL) laser scanner collects the data

using a green-wavelength (532-nanometer) 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 office in St. Petersburg, Florida. The navigational data are processed and then, along

with the raw data, are downloaded into ALPS, or the Airborne Lidar Processing System (20091231 - 20101019). Data are converted from units of time

to x,y,z points for elevation and formatted into .las and .xyz files. The derived surface data can then also be converted into raster data (GeoTIFFs).

This process took place 20091127 through 20101102.

Process Date/Time: 2010-11-02 00:00:00

Process Step 2

CC ID: 1132409

Metadata imported into ArcCatalog from XML file.

Process Date/Time: 2010-12-23 00:00:00

Process Step 3

CC ID: 1132410

The NOAA Office for Coastal Management (OCM) received files in unclassified LAS format. The files contained LiDAR intensity and elevation measurements.

OCM performed the following processing on the data to make it available within Digital Coast:

1. The unclassified data were processed to provide a bare earth surface.

2. The data were converted from UTM, Zone 18 coordinates to geographic coordinates.

3. The data were converted from NAVD88 heights to ellipsoid heights using Geoid09.

4. The LAS header fields were sorted by latitude and updated.

Process Date/Time: 2011-09-01 00:00:00

Catalog Details

Catalog Item ID: 50111
GUID: gov.noaa.nmfs.inport:50111
Metadata Record Created By: Anne Ball
Metadata Record Created: 2017-11-15 15:24+0000
Metadata Record Last Modified By: SysAdmin InPortAdmin
Metadata Record Last Modified: 2022-08-09 17:11+0000
Metadata Record Published: 2022-03-16
Owner Org: OCMP
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Last Review Date: 2022-03-16
Metadata Review Frequency: 1 Year
Metadata Next Review Date: 2023-03-16