Short Citation:
Office for Coastal Management, 2021: EAARL-B Submerged Topography - Saint Croix and Saint Thomas, U.S. Virgin Islands, 2014, https://www.fisheries.noaa.gov/inport/item/48140.

Item Identification

Title: EAARL-B Submerged Topography - Saint Croix and Saint Thomas, U.S. Virgin Islands, 2014
Short Name: 2014_EAARLB_StCroix_StThomas_m4940_metadata
Status: Completed
Publication Date: 2015-07-25
Abstract:

Binary point-cloud data for part of the submerged environs of Saint Croix and Saint Thomas, U.S. Virgin Islands, were produced from remotely sensed, geographically referenced elevation measurements by the U.S. Geological Survey in collaboration with the National Oceanic and Atmospheric Administration's Coral Reef Conservation Program. Elevation measurements were collected over the area using the second-generation Experimental Advanced Airborne Research Lidar, 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 13.5 centimeters on Saint Croix. Data were insufficient to calculate the nominal vertical elevation accuracy expressed as the root mean square error (RMSE) on Saint Thomas. 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.

Original contact information:

Contact Name: Xan Fredericks

Contact Org: Cherokee Nation Technology Solutions, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center, St. Petersburg, FL

Title: Lidar Validation and Processing Analyst

Phone: 727 502-8086

Email: afredericks@usgs.gov

Purpose:

The purpose of this project was to produce highly detailed and accurate seamless digital elevation maps for part of the submerged environs of Saint Croix and Saint Thomas, U.S. Virgin Islands, for use as a management tool and to make these data available to natural-resource managers and research scientists.

Notes:

10163

Supplemental Information:

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 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 although first-surface data include vegetation, buildings, and other man-made 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 North American Vertical Datum of 1988 (using the GEOID12A model).

Funding was from the NOAA Coral Reef Conservation Program.

Keywords

Theme Keywords

Thesaurus Keyword
CoRIS Discovery Thesaurus Geographic Information > LiDAR
CoRIS Theme Thesaurus EARTH SCIENCE > Land Surface > Topography> Terrain Elevation
CoRIS Theme Thesaurus EARTH SCIENCE > Oceans > Bathymetry/Seafloor Topography > Bathymetry
GCMD Instrument LIDAR > LIGHT DETECTION AND RANGING
General Airborne Lidar Processing System
General ALPS
General Cessna 310
General DEM
General Digital Elevation Model
General EAARL-B
General Experimental Advanced Airborne Research Lidar
General laser altimetry
General lidar
General remote sensing
General topography
Global Change Master Directory (GCMD) Science Keywords Earth Science > Land Surface > Topography > Terrain Elevation > Topographical Relief Maps
Global Change Master Directory (GCMD) Science Keywords Earth Science > Oceans > Bathymetry/Seafloor Topography > Seafloor Topography
Global Change Master Directory (GCMD) Science Keywords Earth Science > Oceans > Coastal Processes > Coastal Elevation
Global Change Master Science Directory DOI/USGS/CMG > COASTAL AND MARINE GEOLOGY, U.S. GEOLOGICAL SURVEY, U.S. DEPARTMENT OF INTERIOR
Global Change Master Science Directory OCEAN > BATHYMETRY/SEAFLOOR TOPOGRAPHY > SEAFLOOR TOPOGRAPHY
Global Change Master Science Directory OCEAN > COASTAL PROCESSES > COASTAL ELEVATION
ISO 19115 Topic Category elevation

Temporal Keywords

Thesaurus Keyword
General 2014

Spatial Keywords

Thesaurus Keyword
CoRIS Place Thesaurus COUNTRY/TERRITORY > United States of America > U. S. Virgin Islands > U. S. Virgin Islands > U. S. Virgin Islands (17N064W0000)
CoRIS Place Thesaurus OCEAN BASIN > Atlantic Ocean > Caribbean Sea > Virgin Islands > Lesser Antilles > U. S. Virgin Islands (17N064W0000)
Geographic Names Information System Caribbean
Geographic Names Information System Saint Croix
Geographic Names Information System Saint Thomas
Geographic Names Information System U.S. Virgin Islands
Global Change Master Directory (GCMD) Location Keywords Ocean > Atlantic Ocean > North Atlantic Ocean > Caribbean Sea > Virgin Islands

Stratum Keywords

Thesaurus Keyword
General Submerged

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
Data Presentation Form: Map (digital)
Entity Attribute Overview:

The input parameters for the random consensus filter (RCF) were: grid cell size (buffer) = 1000 centimeters x 1000 centimeters; vertical tolerance (vertical width) = 200 centimeters.

Entity Attribute Detail Citation:

http://pubs.usgs.gov/of/2009/1078/

Distribution Liability:

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

Data Set Credit: 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.

Support Roles

Data Steward

CC ID: 622107
Date Effective From: 2015-07-25
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address: coastal.info@noaa.gov
Phone: (843) 740-1202
URL: https://coast.noaa.gov

Distributor

CC ID: 622109
Date Effective From: 2015-07-25
Date Effective To:
Contact (Organization): Office for Coastal Management (OCM)
Address: 2234 South Hobson Avenue
Charleston, SC 29405-2413
URL: https://www.coast.noaa.gov/

Metadata Contact

CC ID: 622110
Date Effective From: 2015-07-25
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address: coastal.info@noaa.gov
Phone: (843) 740-1202
URL: https://coast.noaa.gov

Point of Contact

CC ID: 622108
Date Effective From: 2015-07-25
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address: coastal.info@noaa.gov
Phone: (843) 740-1202
URL: https://coast.noaa.gov

Extents

Currentness Reference: Ground Condition

Extent Group 1

Extent Group 1 / Geographic Area 1

CC ID: 622123
W° Bound: -65.27130878
E° Bound: -64.41490881
N° Bound: 18.369432
S° Bound: 17.75629702

Extent Group 1 / Time Frame 1

CC ID: 622112
Time Frame Type: Discrete
Start: 2014-03-07

Extent Group 1 / Time Frame 2

CC ID: 622113
Time Frame Type: Discrete
Start: 2014-03-08

Extent Group 1 / Time Frame 3

CC ID: 622114
Time Frame Type: Discrete
Start: 2014-03-11

Extent Group 1 / Time Frame 4

CC ID: 622115
Time Frame Type: Discrete
Start: 2014-03-12

Extent Group 1 / Time Frame 5

CC ID: 622116
Time Frame Type: Discrete
Start: 2014-03-13

Extent Group 1 / Time Frame 6

CC ID: 622117
Time Frame Type: Discrete
Start: 2014-03-14

Extent Group 1 / Time Frame 7

CC ID: 622118
Time Frame Type: Discrete
Start: 2014-03-17

Extent Group 1 / Time Frame 8

CC ID: 622119
Time Frame Type: Discrete
Start: 2014-03-18

Extent Group 1 / Time Frame 9

CC ID: 622120
Time Frame Type: Discrete
Start: 2014-03-19

Extent Group 1 / Time Frame 10

CC ID: 622121
Time Frame Type: Discrete
Start: 2014-03-21

Extent Group 1 / Time Frame 11

CC ID: 622122
Time Frame Type: Discrete
Start: 2014-03-24

Spatial Information

Spatial Representation

Representations Used

Vector: Yes

Access Information

Security Class: Unclassified
Security Classification System:

Unclassified

Security Handling Description:

None

Data Access Procedure:

This data can be obtained on-line at the following URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=4940

The data set is dynamically generated based on user-specified parameters.;

Data Access Constraints:

None

Data Use Constraints:

The U.S. Geological Survey requests to be acknowledged as originator of these data in future products or derivative research.

Distribution Information

Distribution 1

CC ID: 743602
Start Date: 2019-07-01
End Date: Present
Download URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=4940
Distributor: Office for Coastal Management (OCM) (2015-07-25 - Present)
File Name: Customized Download
Description:

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

File Type: Zip

Distribution 2

CC ID: 743603
Start Date: 2019-07-01
End Date: Present
Download URL: https://coast.noaa.gov/htdata/lidar1_z/geoid12b/data/4940
Distributor: Office for Coastal Management (OCM) (2015-07-25 - Present)
File Name: Bulk Download
Description:

Simple download of data files.

File Type: LAZ

URLs

URL 1

CC ID: 743605
URL: https://coast.noaa.gov/dataviewer
Name: Data Access Viewer
URL Type:
Online Resource
Description:

Custom download tool

URL 2

CC ID: 858236
URL: https://coast.noaa.gov/htdata/lidar1_z/geoid12b/data/4940/supplemental/usvi2014_eaarlb_m4940.kmz
Name: browse graphic
URL Type:
Browse Graphic
File Resource Format: kmz
Description:

Browse graphic

Activity Log

Activity Log 1

CC ID: 622156
Activity Date/Time: 2016-05-23
Description:

Date that the source FGDC record was last modified.

Activity Log 2

CC ID: 622155
Activity Date/Time: 2017-11-14
Description:

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

Activity Log 3

CC ID: 717165
Activity Date/Time: 2018-02-08
Description:

Partial upload of Positional Accuracy fields only.

Activity Log 4

CC ID: 743604
Activity Date/Time: 2018-03-13
Description:

Partial upload to move data access links to Distribution Info.

Data Quality

Accuracy:

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.

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; however, a ground-control survey is not completed simultaneously with every lidar survey. Vertical accuracies may differ based on the type of terrain and the accuracy of the GPS and aircraft-attitude measurements.

Completeness Report:

Missing 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.

Conceptual Consistency:

These data are located in UTM Zone 20.

Lineage

Sources

Lidar data

CC ID: 858237
Contact Role Type: Originator
Contact Type: Organization
Contact Name: USGS

Process Steps

Process Step 1

CC ID: 622098
Description:

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 (20140311-20141121). 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 are converted into raster data (GeoTIFFs).

Process Date/Time: 2014-11-21 00:00:00

Process Step 2

CC ID: 622099
Description:

The data were depth calibrated in ALPS (20150106) using a linear model with a slope of 0.98103 and an intercept of -0.000681.

Process Date/Time: 2015-01-06 00:00:00

Process Step 3

CC ID: 622100
Description:

Metadata imported into ArcCatalog 10.1.1.3143 from XML file.

Process Date/Time: 2015-07-06 00:00:00

Process Step 4

CC ID: 622101
Description:

Data were received by the NOAA Office for Coastal Management from Tim Battista and imported into the Digital Coast Data Access Viewer system. Data were reprojected from UTM 20N to geographic coordinates. Vertical values were transformed from orthometric to ellipsoid heights using the NGS GEOID12a model. Compression to an LAZ file was done with the LAStools 'laszip' program and can be unzipped with the same free program (laszip.org)

Process Date/Time: 2015-07-07 00:00:00
Process Contact: Office for Coastal Management (OCM)
Source: Lidar data

Catalog Details

Catalog Item ID: 48140
Metadata Record Created By: Anne Ball
Metadata Record Created: 2017-11-14 14:19+0000
Metadata Record Last Modified By: SysAdmin InPortAdmin
Metadata Record Last Modified: 2019-07-02 15:17+0000
Metadata Record Published: 2018-03-13
Owner Org: OCM
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Next Review Date: 2019-03-14