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Short Citation:
OCM Partners, 2025: 2022 USGS Topobathy Lidar DEM: Breton Island, LA, https://www.fisheries.noaa.gov/inport/item/73968.

Item Identification

Title: 2022 USGS Topobathy Lidar DEM: Breton Island, LA
Status: Completed
Creation Date: 2022
Publication Date: 2024-07-30
Abstract:

Original Dataset Product: These are Digital Elevation Model (DEM) data delivered as part of the Louisiana Breton topobathy lidar project. Class 2 (ground) and class 40 (bathymetry) lidar points were used to create a 0.5-meter merged topo-bathy DEM.

Original Dataset Geographic Extent: Breton, Louisiana, covering approximately 129.4 square miles.

Original Dataset Description: The Louisiana Breton Topobathymetric Lidar project called for the planning, acquisition, processing and derivative products of lidar data to be collected at a nominal pulse spacing (NPS) of 0.35 meters (QL1) for topographic areas and 0.71 meter (QL2b) for bathymetric areas. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, 2024 rev A. The data was developed based on a horizontal projection/datum of NAD83 (2011), UTM zone 16N, meters and vertical datum of NAVD88 (Geoid 18), meters. Lidar data were delivered as processed Classified LAS 1.4 files, formatted to 1570 individual 500 m x 500 m tiles, as tiled Intensity Imagery, and as tiled topobathymetric DEMs; all tiled to the same 500 m x 500 m schema.

Original Dataset Ground Conditions: Lidar was collected from October 6, 2022 to November 3, 2022, while no snow was on the ground and rivers were at or below normal levels. In order to post process the lidar data to meet task order specifications and meet ASPRS vertical accuracy guidelines, Dewberry established 17 ground control points (GCP) and 5 bathymetric control points (BCP) that were used to calibrate the lidar to known ground positions established throughout the project area. An additional 27 independent accuracy checkpoints--20 in bare earth and urban land cover (NVA), 7 in submerged topography land cover (BVA)--were used to assess the vertical accuracy of the data. These checkpoints were not used to calibrate or post-process the data.

This metadata record supports the data entry in the NOAA Digital Coast Data Access Viewer (DAV). For this data set, the DAV is leveraging the USGS GeoTIFF files hosted by USGS on Amazon Web Services.

Purpose:

To acquire detailed surface elevation data for use in conservation planning, design, research, floodplain mapping, dam safety assessments and elevation modeling, etc. Classified LAS files are used to show the manually reviewed bare earth surface. This allows the user to create Intensity Images, Refraction Extents and Raster DEM. The purpose of these lidar data was to produce high accuracy 3D hydro-flattened Digital Elevation Model (DEM) with a 0.5 meter cell size. These lidar point cloud data were used to create intensity images, Refraction Extents, and topobathymetric DEMs as necessary.

Supplemental Information:

Raster File Type = GeoTiff Bit Depth/Pixel Type = 32 bit float Raster Cell Size = 0.5 Meter Interpolation or Resampling Technique = Triangulated Irregular Network Required Vertical Accuracy = 19.6 cm NVA

Keywords

Theme Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Science Keywords
EARTH SCIENCE > LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION
Global Change Master Directory (GCMD) Science Keywords
EARTH SCIENCE > LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION > DIGITAL ELEVATION/TERRAIN MODEL (DEM)
Global Change Master Directory (GCMD) Science Keywords
EARTH SCIENCE > OCEANS > BATHYMETRY/SEAFLOOR TOPOGRAPHY > BATHYMETRY > COASTAL BATHYMETRY
Global Change Master Directory (GCMD) Science Keywords
EARTH SCIENCE > OCEANS > COASTAL PROCESSES > COASTAL ELEVATION

Spatial Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Location Keywords
CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA
Global Change Master Directory (GCMD) Location Keywords
CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA > LOUISIANA
Global Change Master Directory (GCMD) Location Keywords
VERTICAL LOCATION > LAND SURFACE

Instrument Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Instrument Keywords
LIDAR > Light Detection and Ranging

Platform Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Platform Keywords
Airplane > Airplane

Physical Location

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

Data Set Information

Data Set Scope Code: Data Set
Data Set Type: Elevation
Maintenance Frequency: None Planned
Data Presentation Form: Model (digital)
Distribution Liability:

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: Acknowledgement of the U.S. Geological Survey would be appreciated for products derived from these data.

Support Roles

Data Steward

CC ID: 1354630
Date Effective From: 2024
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: 1354629
Date Effective From: 2024
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: 1354633
Date Effective From: 2024
Date Effective To:
Contact (Organization): U.S. Geological Survey
Address: 12201 Sunrise Valley Drive
Reston, VA 20191
USA
URL: USGS Home

Metadata Contact

CC ID: 1354631
Date Effective From: 2024
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: 1354632
Date Effective From: 2024
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: 1354652
W° Bound: -89.235407
E° Bound: -88.802407
N° Bound: 30.07711
S° Bound: 29.443553

Extent Group 1 / Time Frame 1

CC ID: 1354651
Time Frame Type: Range
Start: 2022-10-06
End: 2022-11-03
Description:

Data were collected from Oct 6 - 11, 2022. Reflights were collected on Nov 2, 3, 2022.

Spatial Information

Spatial Representation

Representations Used

Grid: Yes
Vector: No
Text / Table: No
TIN: No
Stereo Model: No
Video: No

Reference Systems

Reference System 1

CC ID: 1354655

Coordinate Reference System

CRS Type: Vertical
EPSG Code: EPSG:5703
EPSG Name: NAVD88 height
See Full Coordinate Reference System Information

Reference System 2

CC ID: 1354654

Coordinate Reference System

CRS Type: Projected
EPSG Code: EPSG:6345
EPSG Name: NAD83(2011) / UTM zone 16N
See Full Coordinate Reference System Information

Access Information

Security Class: Unclassified
Data Access Procedure:

Data is available online for bulk and custom downloads.

Data Access Constraints:

None

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 limitations.

Distribution Information

Distribution 1

CC ID: 1354634
Start Date: 2024
End Date: Present
Download URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=10223/details/10223
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2024 - Present)
File Name: Customized Download
Description:

Create custom data files by choosing data area, map projection, file format, etc. A new metadata will be produced to reflect your request using this record as a base.

Distribution Format: Not Applicable
Compression: Zip

Distribution 2

CC ID: 1354635
Start Date: 2024
End Date: Present
Download URL: https://prd-tnm.s3.amazonaws.com/index.html?prefix=StagedProducts/Elevation/OPR/Projects/LA_BretonIslandTB_D22/LA_BretonIsl_Topobathymetric_D22/TIFF/
Distributor: U.S. Geological Survey (2024 - Present)
File Name: Bulk Download
Description:

Bulk download of data files in GeoTiff format, UTM Zone 16N NAD83(2011), meters coordinates and elevations in NAVD88 (Geoid18) meters.

Distribution Format: GeoTIFF

URLs

URL 1

CC ID: 1354636
URL: https://prd-tnm.s3.amazonaws.com/StagedProducts/Elevation/metadata/LA_BretonIslandTB_D22/LA_BretonIsl_Topobathymetric_D22/reports/LA_BretonIs_TB_Lidar_Project_Report.pdf
Name: Lidar Report
URL Type:
Online Resource
File Resource Format: pdf
Description:

Link to the lidar report.

URL 2

CC ID: 1354637
URL: https://prd-tnm.s3.amazonaws.com/StagedProducts/Elevation/metadata/LA_BretonIslandTB_D22/USGS_LA_BretonIslandTB_D22_ProjectReport.pdf
Name: USGS Project Report
URL Type:
Online Resource
File Resource Format: pdf
Description:

This USGS report provides the project information, vertical accuracy results, list of classifications, sensor used, and work unit information.

URL 3

CC ID: 1354638
URL: https://prd-tnm.s3.amazonaws.com/index.html?prefix=StagedProducts/Elevation/metadata/LA_BretonIslandTB_D22/
Name: USGS Additional Info
URL Type:
Online Resource
Description:

Link to the additional information available for this data set from the USGS. This information includes reports and tile index shapefiles.

URL 4

CC ID: 1354639
URL: https://coast.noaa.gov/dataviewer/
Name: NOAA's Office for Coastal Management (OCM) Data Access Viewer (DAV)
URL Type:
Online Resource
File Resource Format: HTML
Description:

The Data Access Viewer (DAV) allows a user to search for and download elevation, imagery, and land cover data for the coastal U.S. and its territories. The data, hosted by the NOAA Office for Coastal Management, can be customized and requested for free download through a checkout interface. An email provides a link to the customized data, while the original data set is available through a link within the viewer.

Technical Environment

Description:

CZMIL SuperNOVA; CARIS; LAStools; Microstation; Terrascan; ArcGIS 10.6; Microsoft Windows 10 Enterprise Service Pack 1

Data Quality

Horizontal Positional Accuracy:

Only checkpoints photo-identifiable in the intensity imagery can be used to test the horizontal accuracy of the lidar. Photo-identifiable checkpoints in intensity imagery typically include checkpoints located at the ends of paint stripes on concrete or asphalt surfaces or checkpoints located at 90 degree corners of different reflectivity, e.g. a sidewalk corner adjoining a grass surface. The xy coordinates of checkpoints, as defined in the intensity imagery, are compared to surveyed xy coordinates for each photo-identifiable checkpoint. These differences are used to compute the tested horizontal accuracy of the lidar. As not all projects contain photo-identifiable checkpoints, the horizontal accuracy of the lidar cannot always be tested.

Lidar vendors calibrate their lidar systems during installation of the system and then again for every project acquired. Typical calibrations include cross flights that capture features from multiple directions that allow adjustments to be performed so that the captured features are consistent between all swaths and cross flights from all directions. This data set was produced to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 41 cm RMSEx/RMSEy Horizontal Accuracy Class which equates to Positional Horizontal Accuracy = +/- 1 meter at a 95% confidence level.

Horizontal accuracy testing requires well-defined checkpoints that can be visually identified in the dataset. Elevation datasets, including lidar datasets, do not always contain well-defined checkpoints suitable for horizontal accuracy assessment. Dewberry reviewed all NVA checkpoints to determine which, if any, of these checkpoints were located on photo-identifiable features in the intensity imagery. This subset of checkpoints was used for horizontal accuracy testing.

The horizontal accuracy testing steps used by Dewberry are summarized as follows:

1. Dewberry's team surveyed X, Y, and Z coordinates for discrete checkpoints in accordance with project specifications. Dewberry targeted half of the NVA checkpoints for location on features that would photo-identifiable in the intensity imagery.

2. Following initial processing, Dewberry located the photo-identifiable features in the intensity imagery.

3. Dewberry computed the differences in X and Y values between the surveyed coordinates and the lidar coordinates of the photo-identifiable feature.

4. Horizontal accuracy was assessed based on these data using NSSDA methodology where horizontal accuracy is calculated at the 95% confidence level.

Vertical Positional Accuracy:

USGS DEM Determined Vertical Accuracy

Non-Vegetated Vertical Accuracy (NVA) = 9.68 cm RMSE

Bathymetric Vertical Accuracy (BVA) = 21.69 cm at the 95th Percentile

Completeness Report:

Topobathymetric data covers the project boundary to the fullest extent possible depending on water clarity, environmental conditions, and sensor signal returns. The raw point cloud is of good quality and data passes Non-Vegetated Vertical Accuracy specifications.

Conceptual Consistency:

Data covers the entire area specified for this project.

Data Management

Have Resources for Management of these Data Been Identified?: Yes
Approximate Percentage of Budget for these Data Devoted to Data Management: Unknown
Do these Data Comply with the Data Access Directive?: Yes
Actual or Planned Long-Term Data Archive Location: NCEI-NC
How Will the Data Be Protected from Accidental or Malicious Modification or Deletion Prior to Receipt by the Archive?:

Data is backed up to cloud storage.

Lineage

Lineage Statement:

The NOAA Office for Coastal Management (OCM) ingested references to the USGS GeoTIFF files that are hosted on Amazon Web Services (AWS), into the Digital Coast Data Access Viewer (DAV). The DAV accesses the raster data as it resides on AWS.

Sources

USGS GeoTIFF Files

CC ID: 1354645
Contact Role Type: Publisher
Contact Type: Organization
Contact Name: USGS
Citation URL: https://prd-tnm.s3.amazonaws.com/index.html?prefix=StagedProducts/Elevation/OPR/Projects/LA_BretonIslandTB_D22/LA_BretonIsl_Topobathymetric_D22/TIFF/
Citation URL Name: USGS GeoTIFF Files

Process Steps

Process Step 1

CC ID: 1354646
Description:

The boresight for each lift was done individually as the solution may change slightly from lift to lift. The following steps describe the Raw Data Processing and Boresight process: 1) Technicians processed the raw data to LAS format flight lines using the final GPS/IMU solution. This LAS data set was used as source data for boresight. 2) Technicians first used proprietary and commercial software to calculate initial boresight adjustment angles based on sample areas selected in the lift. These areas cover calibration flight lines collected in the lift, cross tie and production flight lines. These areas are well distributed in the lift coverage and cover multiple terrain types that are necessary for boresight angle calculation. The technician then analyzed the results and made any necessary additional adjustment until it is acceptable for the selected areas. 3) Once the boresight angle calculation was completed for the selected areas, the adjusted settings were applied to all of the flight lines of the lift and checked for consistency. The technicians utilized commercial and proprietary software packages to analyze how well flight line overlaps match for the entire lift and adjusted as necessary until the results met the project specifications. 4) Once all lifts were completed with individual boresight adjustment, the technicians checked and corrected the vertical misalignment of all flight lines and also the matching between data and ground truth. The relative accuracy was less than or equal to 6 cm RMSEz within individual swaths and less than or equal to 8 cm RMSEz or within swath overlap (between adjacent swaths). 5) The technicians ran a final vertical accuracy check of the boresighted flight lines against the surveyed check points after the z correction to ensure the requirement of NVA = 19.6 cm 95% Confidence Level (Required Accuracy) was met. Point classification was performed according to USGS Lidar Base Specification 2024 rev A. Bare earth DEMs were exported from the classified point cloud.

Process Date/Time: 2024-03-28 00:00:00

Process Step 2

CC ID: 1354647
Description:

Dewberry used algoritms in TerraScan to create the intial ground/submerged topography surface.

Dewberry used rasterized aggregate extents of refracted points to create automated 2-D breaklines with LAStools and ArcGIS. Light travels at different speeds in air versus water and its speed and direction of travel change when it enters the water column. The refraction correction process accounts for this difference by adjusting the depth (distance traveled) and horizontal position (change of angle/direction) of the lidar points acquired within water. These breaklines delineate areas where the refraction correction was applied to the lidar data by Dewberry proprietary refraction correction tool.

Dewberry used the 2-D refraction extents and additional bathy features to classify the bathymetric bottom and ground points properly in TerraScan.

The withheld bit was set on class 7 and class 18 in TerraScan after all classification was complete.

All lidar data was peer-reviewed. Dewberry's QAQC also included creating void polygons for use during review. All necessary edits were applied to the dataset. LASTools software was used to update LAS header information, including all projection and coordinate reference system information. The final lidar data are in LAS format 1.4 and point data record format 6.

All data was then verified by an Independent QC department within Dewberry. The independent QC was performed by separate analysts who did not perform manual classification or editing. The independent QC involved quantitative and qualitative reviews.

Process Date/Time: 2024-04-05 00:00:00

Process Step 3

CC ID: 1354648
Description:

Data was tested at 0.30 meter nominal pulse spacing and 11.02 points per square meter (ppsm). The average density was tested on the LAS data using geometrically reliable (withheld and noise points excluded) first-return points. (A)NPD was tested using rasters which produce the average number of points within each cell.

Process Date/Time: 2024-04-05 00:00:00

Process Step 4

CC ID: 1354649
Description:

Digital elevation models were created using only ground (2) and submerged topography (40) lidar point data. A triangulated irregular network (TIN) was generated from these data and rasterized at a 0.5 m spatial resolution using the LAStools 'blast2dem' utility. Void polygons delineating areas of extremely sparse or non-existent bathymetric coverage were used in ArcGIS to clip large areas of interpolation in the DEM. The void polygon creation process is described in the void polygon metadata and final project report.

Process Date/Time: 2024-04-05 00:00:00

Process Step 5

CC ID: 1354656
Description:

DEMs were reviewed using Global Mapper and ArcGIS to check for surface anomalies, incorrect elevations, and unacceptable voids in the data.

Process Date/Time: 2024-04-07 00:00:00

Process Step 6

CC ID: 1354657
Description:

The NOAA Office for Coastal Management (OCM) created references to the USGS GeoTIFF files that were ingested into the NOAA Digital Coast Data Access Viewer (DAV). No changes were made to the data. The DAV will access the raster data as it resides on Amazon Web Services (AWS).

This is the location of the GeoTIFF files that are being accessed:

https://prd-tnm.s3.amazonaws.com/index.html?prefix=StagedProducts/Elevation/OPR/Projects/LA_BretonIslandTB_D22/LA_BretonIsl_Topobathymetric_D22/TIFF/

Process Date/Time: 2024-12-06 00:00:00
Process Contact: Office for Coastal Management (OCM)

Related Items

Item Type Relationship Type Title
Data Set (DS) Cross Reference 2022 USGS Topobathy Lidar: Breton Island, LA

Catalog Details

Catalog Item ID: 73968
GUID: gov.noaa.nmfs.inport:73968
Metadata Record Created By: Rebecca Mataosky
Metadata Record Created: 2024-12-10 19:15+0000
Metadata Record Last Modified By: Rebecca Mataosky
Metadata Record Last Modified: 2024-12-10 19:55+0000
Metadata Record Published: 2024-12-10
Owner Org: OCMP
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Last Review Date: 2024-12-09
Metadata Review Frequency: 1 Year
Metadata Next Review Date: 2025-12-09