U.S. Geological Survey
2015
EAARL-B Coastal Topography--Chandeleur Islands, Louisiana, 2012: Seamless (Bare Earth and Submerged) (.las file)
first
vector digital data
U.S. Geological Survey Data Series
913
St. Petersburg, FL
U.S. Geological Survey
https://pubs.usgs.gov/ds/0913/
Binary point-cloud data of a portion of the Chandeleur Islands, Louisiana, 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 second-generation Experimental Advanced Airborne Research Lidar (EAARL-B), 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 55 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 0.5 - 1.6 meters. The nominal vertical elevation accuracy expressed as the root mean square error (RMSE) is 15 centimeters. A peak sampling rate of 15 - 30 kilohertz 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 produce highly detailed and accurate seamless digital elevation maps of a portion of the Chandeleur Islands, Louisiana, for use as a management tool and to make these data available to natural-resource managers and research scientists.
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 originally by a USGS-NASA collaborative project. Specialized processing algorithms are used to convert raw waveform lidar data acquired by the EAARL-B 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 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-B 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 GEOID12A model). Each file contains data located in a 2-kilometer by 2-kilometer tile, where the upper-left bound can be ascertained 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, sm_e123_n4567_16).
The development of custom software for creating these data products has been supported by the U.S. Geological Survey CMGP's Lidar for Science and Resource Management project. Processed data products are used by the U.S. Geological Survey CMGP'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.
20120807
20120808
ground condition
None planned
ISO 19115 Topic Category
elevation
General
Airborne Lidar Processing System
ALPS
Cessna 310
Digital Elevation Model
DEM
EAARL-B
Experimental Advanced Airborne Research Lidar
laser altimetry
lidar
remote sensing
topography
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
Geographic Names Information System
St. Bernard Parish
Chandeleur Islands
Louisiana
Gulf of Mexico
General
Seamless (bare earth and submerged)
General
2012
None
The U.S. Geological Survey requests to be acknowledged as originators of these data in future products or derivative research.
Xan Fredericks
Cherokee Nation Technology Solutions, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
Lidar Validation and Processing Analyst
mailing and physical address
600 4th Street South
St. Petersburg
FL
33701
USA
727 502-8086
727 502-8182
afredericks@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 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.
Unclassified
Unclassified
None
Microsoft Windows XP Version 5.1 (Build 2600) Service Pack 2; Esri ArcCatalog 10.1.1.3143
3.2400 E+5
3.2600 E+5
3.31800 E+6
3.31600 E+6
-88.8243072854869
-88.8032592307225
29.9805596225998
29.9622340056783
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.
Each file contains data located in a 2-kilometer by 2-kilometer tile where the upper-left bound can be ascertained 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, sm_e123_n4567_16).
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 GPS and aircraft-attitude measurements.
The data were collected using a Cessna 310 aircraft. The EAARL-B 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 (20131220 - 20140812). Data are converted from units of time to x,y,z points for elevation and formatted into .las and .xyz files, and the derived surface data is converted into raster data (GeoTIFFs).
20120807 through 20140812
Xan Fredericks
Cherokee Nation Technology Solutions, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
Lidar Validation and Processing Analyst
mailing and physical address
600 4th Street South
St. Petersburg
FL
33701
USA
727 502-8086
afredericks@usgs.gov
M-F, 8:00-4:00 ET
Metadata imported into ArcCatalog 10.1.1.3143 from XML file.
20150123
Xan Fredericks
Cherokee Nation Technology Solutions, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
Lidar Validation and Processing Analyst
mailing and physical address
600 4th Street South
St. Petersburg
FL
33701
USA
727 502-8086
M-F, 8:00-4:00 ET
afredericks@usgs.gov
Point
row and column
1.000000
1.000000
meters
Universal Transverse Mercator
16
0.999600
-87.000000
0.000000
500000.000000
0.000000
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
The input parameters for the random consensus filter (RCF) were: grid cell size (buffer) = 600 centimeters x 600 centimeters for bare earth and 1000 centimeters x 1000 centimeters for submerged topography; vertical tolerance (vertical width) = 20 centimeters for bare earth and 40 centimeters for submerged topography.
https://pubs.usgs.gov/of/2009/1078/
U.S. Geological Survey
Xan Fredericks
Lidar Validation and Processing Analyst
mailing and physical address
600 4th Street South
St. Petersburg
FL
33701
USA
727 502-8086
M-F, 8:00-4:00 ET
DS 913
Although these data have been processed successfully on a computer system at the U.S. Geological Survey (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.
BINARY
ASPRS LAS
1.2
https://pubs.usgs.gov/ds/0913/
None
Contact U.S. Geological Survey.
Vary
Contact U.S. Geological Survey for details.
20120807
20120808
20150123
Xan Fredericks
Cherokee Nation Technology Solutions, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
Lidar Validation and Processing Analyst
mailing and physical address
600 4th Street South
St. Petersburg
FL
33701
USA
727 502-8086
M-F, 8:00-4:00 ET
afredericks@usgs.gov
FGDC Content Standards for Digital Geospatial Metadata
FGDC-STD-001-1998
local time
http://www.esri.com/metadata/esriprof80.html
Esri Metadata Profile