U.S. Geological Survey
2016
EAARL Coastal Topography-Louisiana, Alabama, and Florida, June 2008
first
XYZ point cloud data
U.S. Geological Survey Data Release
doi:10.5066/F7G15XZX
St. Petersburg, FL
U.S. Geological Survey
https://doi.org/10.5066/F7G15XZX
ASCII XYZ point cloud data were produced from remotely sensed, geographically referenced elevation measurements by the U.S. Geological Survey (USGS). Elevation measurements were collected over the area using the National Aeronautics and Space Administration (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, 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 3 centimeters. A sampling rate of 3 kilohertz or higher results in an extremely dense spatial elevation dataset. Over 100 kilometers of coastline can be surveyed easily within a 3- to 4-hour mission. When resultant elevation maps for an area are analyzed, they provide a useful tool to make management decisions regarding land development.
The purpose of this project was to provide first return elevation data collected during a June 24-26, 2008 airborne lidar survey for the Chandeleur Islands, LA, Dauphin Island, AL, Santa Rosa Island, FL, and Bon Secour, AL for use as a management tool and to make these data available to natural-resource managers and research scientists. To ensure that St. Petersburg Coastal and Marine Science Center (SPCMSC) data management protocols were followed, this survey was assigned a USGS field activity number (FAN), 08ACH03. Additional survey and data details are available at https://cmgds.marine.usgs.gov/fan_info.php?fan=08ACH03.
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 USGS'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 originally 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 "first returns" are indicative of vegetation-canopy height, or bare ground in the absence of vegetation, whereas "last returns" typically represent "bare-earth" elevations under vegetation. The terms first surface and bare earth refer to the digital elevation data of the terrain, but while first-surface data include vegetation, buildings, and other manmade structures, bare-earth data do not. The zero crossing of the second derivative (that is, detection of stationary points) 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.
The development of custom software for creating these data products has been supported by the USGS CMGP's Lidar for Science and Resource Management project. Processed data products are used by the U.S. Geological Survey CMGP's National Assessment 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.
20080624
20080626
ground condition
None planned
-88.88685383
-86.50184294
30.40365017
29.75905017
USGS Metadata Identifier
USGS:667eea30-2662-477a-a027-dd710c3c9d8c
ISO 19115 Topic Category
elevation
None
Airborne Lidar Processing System
ALPS
EAARL
Experimental Advanced Airborne Research Lidar
laser altimetry
USGS National Assessment of Coastal Change Hazards Project
ASCII XYZ (First return)
Global Change Master Science Directory
LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION
Global Change Master Science Directory
LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION
OCEAN > COASTAL PROCESSES > BARRIER ISLANDS
OCEAN > COASTAL PROCESSES > BEACHES
OCEAN > COASTAL PROCESSES > SHORELINE DISPLACEMENT
DOI/USGS/CMG > COASTAL AND MARINE GEOLOGY, U.S. GEOLOGICAL SURVEY, U.S. DEPARTMENT OF INTERIOR
GCMD Instrument
LIDAR > LIGHT DETECTION AND RANGING
Data Categories for Marine Planning
distributions
bathymetry and elevation
Marine Realms Information Bank (MRIB) Keywords
altimetry
topographic mapping
USGS Thesaurus
lidar
topography
remote sensing
digital elevation models
Geographic Names Information System
Chandeleur Islands
Dauphin Island
Santa Rosa Island
Bon Secour
Alabama
Florida
Louisiana
Gulf of Mexico
None
First return
None
2008
None
The U.S. Geological Survey requests to be acknowledged as originator of these data in future products or derivative research.
Joseph Long
USGS
mailing and physical address
600 4th Street South
St. Petersburg
FL
33701
USA
772 502-8024
727 502-8182
jwlong@usgs.gov
M-F, 8:00-4:00 ET
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 USGS 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.
Unclassified
Unclassified
None
Microsoft Windows 2000 Version 5.2 (Build 3790) Service Pack 1; ESRI ArcCatalog 9.1.0.722
Nayegandhi, A., Brock, J.C., and Wright, C.W.
2009
Small footprint, waveform-resolving lidar estimation of submerged and subcanopy topography in coastal environments
International Journal of Remote Sensing
30(4), p. 861-878
The expected accuracy of the measured variables is as follows: attitude within 0.05 degree, 3 centimeters nominal ranging accuracy, and vertical elevation accuracy of 15 centimeters RMSE for the submerged topographic surface. Quality checks are built into the data-processing software.
No known issues.
These point-cloud data may appear sparse or nonexistent, which is a result of removal from manual editing or lack of survey coverage.
Raw elevation measurements have been determined to be within 1 meter in horizontal accuracy.
Typical vertical elevation accuracies for these data are consistent with the point elevation data; 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 Geographical Positioning System (GPS) and aircraft-attitude measurements.
The data were collected using a Cessna 310 aircraft. The 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 USGS office in St. Petersburg, Florida. Raw EAARL waveform, GPS, and Inertial Measurement Unit (IMU) data loaded into ALPS software. ALPS (v. 1.55) was used to interactively process small sections of data to obtain best estimates of aircraft pitch and roll biases. Pitch and roll biases are 0.30 and -1.4 respectively.
20090508
Joseph Long
USGS
mailing and physical address
600 4th Street South
St. Petersburg
FL
33701
USA
772 502-8024
jwlong@usgs.gov
M-F, 8:00-4:00 ET
ALPS (v. 1.55) batch processed the raw data for first and last return topography then batch filtered the first return topography, using the RCF. The input parameters of the RCF were: grid cell size (buffer) = 500 cm x 500 cm; vertical tolerance = 40.
20090508
J. Long
USGS
Research Oceanographer
Physical and Mailing
600 4th Street South
St. Petersburg
FL
33701
USA
(727) 502-8024
jwlong@usgs.gov
ALPS (v. 1.55) was used to convert first return topography from ITRF00 to NAD83, NAVD88 using the Geoid96 model. Lastly, ALPS exported the NAD83, NAVD88 (Geoid96) first return topography, for each survey line, to ASCII XYZ files.
20090508
J. Long
USGS
Research Oceanographer
Physical and Mailing
600 4th Street South
St. Petersburg
FL
33701
USA
(727) 502-8024
jwlong@usgs.gov
Using Linux, the first return ASCII XYZ files were concatenated into a single file consisting of three columns, longitude, latitude, and elevation.
20090508
J. Long
USGS
Research Oceanographer
Physical and Mailing
600 4th Street South
St. Petersburg
FL
33701
USA
(727) 502-8024
jwlong@usgs.gov
Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog.
20170124
U.S. Geological Survey
Alan O. Allwardt
Contractor -- Information Specialist
mailing and physical address
2885 Mission Street
Santa Cruz
CA
95060
831-460-7551
831-427-4748
aallwardt@usgs.gov
Keywords section of metadata optimized by adding USGS thesaurus keywords and correcting DOI links.
20180524
U.S. Geological Survey
Arnell S. Forde
Geologist
mailing and physical address
600 4th Street South
St. Petersburg
FL
33701
727-502-8000
aforde@usgs.gov
Added keywords section with USGS persistent identifier as theme keyword.
20201013
U.S. Geological Survey
VeeAnn A. Cross
Marine Geologist
Mailing and Physical
384 Woods Hole Road
Woods Hole
MA
02543-1598
508-548-8700 x2251
508-457-2310
vatnipp@usgs.gov
Point
North American Datum of 1983
Geodetic Reference System 80
6378137.000000
298.25722210100002
North American Vertical Datum of 1988
0.20
meters
Explicit elevation coordinate included with horizontal coordinates
08ACH03_first_return.xyz
This XYZ file (.xyz) contains coordinate and elevation data, in ASCII comma-delimited format.
U.S. Geological Survey
Longitude
decimal degrees
NAD 83
-88.8869
-86.5018
Latitude
decimal degrees
NAD 83
29.7951
30.4037
Elevation
Elevation in meters
NAVD 88 (Geoid96)
-21.48
151.42
This file consists of first return elevation data available for this survey. Data has been processed via the ALPS processing software. Data has been quality controlled though the application of the RCF in ALPS. Data has been converted from the ITRF00 reference frame to NAD83, NAVD88 (Geoid96).
https://pubs.usgs.gov/of/2009/1078/
J. Long
USGS
Research Oceanographer
Physical and Mailing
600 4th Street South
St. Petersburg
FL
33701
USA
(727) 502-8024
jwlong@usgs.gov
08ACH03_first_return.xyz
Although these data have been processed successfully on a computer system at the USGS, 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 USGS shall not be held liable for improper or incorrect use of the data described and/or contained herein. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
ASCII
1
XYZ
https://coastal.er.usgs.gov/data-release/doi-F7G15XZX/data/08ACH03_first_return.zip
Available Online
Prices vary. None, if obtained online.
20201013
K. Morgan
USGS
Geologist
Physical and Mailing
600 4th Street South
St. Petersburg
FL
33701
USA
(727) 502-8037
kmorgan@usgs.gov
FGDC Content Standards for Digital Geospatial Metadata
FGDC-STD-001-1998
local time