Xan Fredericks
Uri S. ten Brink
Brian F. Atwater
Christine J. Kranenburg
David B. Nagle
20160922
Lidar-Derived Seamless (Bare Earth and Submerged) Digital Elevation Model (DEM) Mosaic for Coastal Topography—Anegada, British Virgin Islands, 2014
first
raster digital data
U.S. Geological Survey Data Release
doi:10.5066/F7GM85F3
St. Petersburg, FL
U.S. Geological Survey
https://doi.org/10.5066/F7GM85F3
A seamless (bare earth and submerged) topography Digital Elevation Model (DEM) mosaic for a portion of the submerged environs of Anegada, British Virgin Islands, was produced from remotely sensed, geographically referenced elevation measurements collected March 19-20, 2014 by the U.S. Geological Survey. 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 20 centimeters. A peak sampling rate of 15-30 kilohertz results in an extremely dense spatial elevation dataset. More than 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 a highly detailed and accurate digital elevation map for a portion of the environs of Anegada, British Virgin Islands, for use as a management tool and to make these data available to natural-resource managers and research scientists. To ensure that SPCMSC data management protocols were followed, this survey was retroactively assigned a USGS field activity number (FAN), 14CNT03. Additional survey and data details are available at http://cmgds.marine.usgs.gov/fan_info.php?fan=14CNT03.
Raw lidar data are not in a format that is generally usable by natural-resource managers and research 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 multitiered 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, although 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, whereas the trailing edge algorithm (that is, the algorithm searches for the location before 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 part 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 Virgin Islands Vertical Datum of 2009 (using GEOID12A); please note that these data are not suitable for determining absolute elevation measurements.
20140319
20140320
ground condition
None planned
-65.49914931
-64.15642329
18.79009075
18.60698663
USGS Metadata Identifier
USGS:a7f18018-5155-4b32-93d1-ebf7d0d897e0
ISO 19115 Topic Category
elevation
None
Airborne Lidar Processing System
ALPS
Cessna 310
DEM
EAARL-B
Experimental Advanced Airborne Research Lidar
laser altimetry
lidar
remote sensing
topography
Global Change Master Science Directory
OCEAN > BATHYMETRY/SEAFLOOR TOPOGRAPHY > SEAFLOOR TOPOGRAPHY
OCEAN > COASTAL PROCESSES > COASTAL ELEVATION
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
digital elevation models
Geographic Names Information System
Anegada
British Virgin Islands
Caribbean Sea
None
Seamless (bare earth and submerged)
None
2014
None
Public domain data from the U.S. Government are freely redistributable with proper metadata and source attribution. The U.S. Geological Survey requests to be acknowledged as originator of these data in future products or derivative research.
Xan Fredericks
U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
Cartographer/Lidar Coordinator
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 periods may be inaccurate because of 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 7 Enterprise Service Pack 1; Esri ArcCatalog 10.1.1.3143
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
v. 30 no. 4, p. 861-878
The expected accuracy of the measured variables is as follows: attitude within 0.05 degree and 3 centimeters nominal ranging accuracy. Quality checks are built into the data-processing software.
These data are located in UTM Zone 20.
Missing areas are represented by a "no data" value of -32,767 and 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.
Raw lidar measurements have been determined to be within 1 meter in horizontal accuracy.
The nominal vertical elevation accuracy of the point elevation data expressed as the root mean square error (RMSE) is 20 centimeters. Typical vertical elevation accuracies for these data are consistent with the point elevation data.
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 (20140311-20160831). Data are converted from units of time to x,y,z points for elevation, which are then manually edited and quality checked to ensure anomalies and noise have been addressed to specification. The data are then datum converted to the Virgin Islands Vertical Datum of 2009 using GEOID12A. The derived surface data are then converted into raster data (GeoTIFF).
20160831
Xan Fredericks
U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
Cartographer/Lidar Coordinator
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
The submerged data were depth calibrated in ALPS (20160831) using a linear model with a slope of 0.98103 and an intercept of -0.000681.
20160831
Christine Kranenburg
Cherokee Nation Technology Solutions, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
Programmer/Analyst
mailing and physical address
600 4th Street South
St. Petersburg
FL
33701
USA
727 502-8129
ckranenburg@usgs.gov
M-F, 7:30-3:30 ET
Metadata imported into ArcCatalog 10.1.1.3143 from XML file.
20160919
Xan Fredericks
U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
Cartographer/Lidar Coordinator
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
Keywords section of metadata optimized for discovery in USGS Coastal and Marine Geology Data Catalog.
20170104
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
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
Tiling Index
Raster
Pixel
Universal Transverse Mercator
20
0.999600
-63.000000
0
500000.000000
0
row and column
2.500000
2.500000
meters
North American Datum of 1983
Geodetic Reference System 80
6378137.000000
298.25722210100002
Virgin Islands Vertical Datum of 2009 (GEOID12A)
0.20
meters
Explicit elevation coordinate included with horizontal coordinates
The input parameters for the random consensus filter (RCF) were: grid cell size (buffer) = 1000 centimeters x 1000 centimeters; vertical tolerance (vertical width) = 100 centimeters for submerged topography and grid cell size (buffer) = 600 centimeters x 600 centimeters; vertical tolerance (vertical width) = 60 centimeters for bare earth topography. Each pixel of the encoded GeoTIFF has an explicit elevation value associated with it. The GeoTIFF grid, which is provided at a 2.5-meter horizontal resolution, is encoded with the interpolated elevation value. The GeoTIFFs are created using Delaunay triangulation, followed by linear interpolation based on the routines in the Exelis Visual Information Solutions Interactive Data Language (IDL) code. The GeoTIFFs were mosaicked using ERDAS Imagine 2014 Mosaic Pro.
http://pubs.usgs.gov/of/2009/1078/
U.S. Geological Survey
Xan Fredericks
Cartographer/Lidar Coordinator
mailing and physical address
600 4th Street South
St. Petersburg
FL
33701
USA
727 502-8086
M-F, 8:00-4:00 ET
ANGD2014_EAARLB_z20_v09g12A_mosaic.tif
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 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.
GeoTIFF
2
GeoTIFF
https://coastal.er.usgs.gov/data-release/doi-F7GM85F3/data/ANGD2014_EAARLB_z20_v09g12A_mosaic.zip
None
Contact U.S. Geological Survey.
Vary
Contact U.S. Geological Survey for details.
20201102
Xan Fredericks
U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL
Cartographer/Lidar Coordinator
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
Content Standard for Digital Geospatial Metadata
FGDC-STD-001-1998
local time