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Short Citation:
National Geodetic Survey, 2024: 2019-2020 NOAA NGS Topobathy Lidar DEM: Coastal VA, NC, SC, https://www.fisheries.noaa.gov/inport/item/66714.

Item Identification

Title: 2019-2020 NOAA NGS Topobathy Lidar DEM: Coastal VA, NC, SC
Status: Completed
Publication Date: 2022
Abstract:

NOAA Florence Topobathymetric Lidar data were collected by NV5 Geospatial (NV5) in 9 blocks from 20191126 - 20200825 using the follow sensors:

Block01 -Riegl VQ880GII system

Block02 - Riegl VQ-880-G and Riegl VQ-880-GII systems

Block03 - Riegl VQ880G, Riegl VQ880GII, and Riegl VQ880GH systems

Block04 - Riegl VQ880GII and Leica Chiroptera 4x systems

Block05 - Riegl VQ880GII, Leica Chiroptera 4x and Hawkeye systems

Block06 - Riegl VQ880GII, Leica Chiroptera 4x and Hawkeye systems

Block07 - Riegl VQ880G, Riegl VQ880GII, and Leica Chiroptera 4x systems

Block08 - Riegl VQ880G and Riegl VQ880GII systems

Block09 - Riegl VQ880G and Riegl VQ880GII systems

This dataset includes topobathymetric data in a LAS format 1.4, point data record format 6, with classifications in accordance with project specifications and the American Society for Photogrammetry and Remote Sensing (ASPRS) classification standards.

This data set also includes LiDAR intensity values, number of returns, return number, time, and scan angle. The 100 meter buffered project area consists of approximately 3,075,010 acres along the Eastern coast of Virginia, North Carolina, and South Carolina.

The delivered classified lidar data were then transformed from ellipsoid to geoidal height (Geoid18) and used to create topobathymetric DEMs in GeoTIFF format with 1m pixel resolution.

Purpose:

This lidar data was required by National Oceanic and Atmospheric Administration (NOAA) and the National Geodetic Survey (NGS), Remote Sensing Division Coastal Mapping Program (CMP) to enable accurate and consistent measurement of the national shoreline. The CMP works to provide a regularly updated and consistent national shoreline to define America's marine territorial limits and manage coastal resources.

Supplemental Information:

This dataset includes all lidar returns. An automated grounding classification algorithm was used to determine bare earth and submerged topography point classification. The automated grounding was followed with manual editing. Depth values were adjusted per sensor to NOAA provided ground truth data. Bathymetric intensity values were normalized for water depth. Classes 2 (ground), 40 (submerged topography), and 43 (submerged object) were used to create the final DEMs. The full workflow used for this project will be documented in the NOAA Florence Topobathymetric Lidar final report, to be provided upon project completion.

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
Global Change Master Directory (GCMD) Science Keywords
EARTH SCIENCE > SPECTRAL/ENGINEERING > LIDAR
ISO 19115 Topic Category
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 > NORTH CAROLINA
Global Change Master Directory (GCMD) Location Keywords
CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA > SOUTH CAROLINA
Global Change Master Directory (GCMD) Location Keywords
CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA > VIRGINIA
Global Change Master Directory (GCMD) Location Keywords
VERTICAL LOCATION > LAND SURFACE
Global Change Master Directory (GCMD) Location Keywords
VERTICAL LOCATION > SEA FLOOR

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: National Oceanic and Atmospheric Administration (NOAA), National Geodetic Survey (NGS), Remote Sensing Division (RSD), Coastal Mapping Program (CMP)

Support Roles

Data Steward

CC ID: 1128671
Date Effective From: 2022
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: 1128669
Date Effective From: 2022
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

Metadata Contact

CC ID: 1128670
Date Effective From: 2022
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

Originator

CC ID: 1128672
Date Effective From: 2022
Date Effective To:
Contact (Organization): National Geodetic Survey (NGS)
Address: 1315 East-West Hwy
Silver Spring, MD 20910
URL: https://geodesy.noaa.gov/

Extents

Currentness Reference: Ground Condition

Extent Group 1

Extent Description:

Block01

Extent Group 1 / Geographic Area 1

CC ID: 1297265
W° Bound: -77.904502
E° Bound: -77.289632
N° Bound: 34.545077
S° Bound: 34.12689

Extent Group 1 / Time Frame 1

CC ID: 1297264
Time Frame Type: Range
Start: 2019-11-26
End: 2019-12-21

Extent Group 2

Extent Description:

Block02

Extent Group 2 / Geographic Area 1

CC ID: 1297268
W° Bound: -77.510503
E° Bound: -76.4876
N° Bound: 34.877717
S° Bound: 34.527625

Extent Group 2 / Time Frame 1

CC ID: 1297267
Time Frame Type: Range
Start: 2019-11-28
End: 2020-03-18

Extent Group 3

Extent Description:

Block03

Extent Group 3 / Geographic Area 1

CC ID: 1297271
W° Bound: -79.40181
E° Bound: -77.800145
N° Bound: 34.285932
S° Bound: 33.16496

Extent Group 3 / Time Frame 1

CC ID: 1297270
Time Frame Type: Range
Start: 2019-11-26
End: 2020-04-02

Extent Group 4

Extent Description:

Block04

Extent Group 4 / Geographic Area 1

CC ID: 1297274
W° Bound: -76.592761
E° Bound: -75.933037
N° Bound: 35.203366
S° Bound: 34.646674

Extent Group 4 / Time Frame 1

CC ID: 1297273
Time Frame Type: Range
Start: 2019-12-08
End: 2020-08-25

Extent Group 5

Extent Description:

Block05

Extent Group 5 / Geographic Area 1

CC ID: 1297277
W° Bound: -75.996936
E° Bound: -75.4444
N° Bound: 35.8734
S° Bound: 35.10379

Extent Group 5 / Time Frame 1

CC ID: 1297276
Time Frame Type: Range
Start: 2019-12-10
End: 2020-07-27

Extent Group 6

Extent Description:

Block06

Extent Group 6 / Geographic Area 1

CC ID: 1297280
W° Bound: -76.1174
E° Bound: -75.55938
N° Bound: 36.945709
S° Bound: 35.8646

Extent Group 6 / Time Frame 1

CC ID: 1297279
Time Frame Type: Range
Start: 2019-11-26
End: 2020-06-22

Extent Group 7

Extent Description:

Block07

Extent Group 7 / Geographic Area 1

CC ID: 1297283
W° Bound: -77.16282
E° Bound: -76.36149
N° Bound: 35.37506
S° Bound: 34.81832

Extent Group 7 / Time Frame 1

CC ID: 1297282
Time Frame Type: Range
Start: 2019-12-07
End: 2020-04-04

Extent Group 8

Extent Description:

Block08

Extent Group 8 / Geographic Area 1

CC ID: 1297286
W° Bound: -77.147204
E° Bound: -75.65982
N° Bound: 35.82732
S° Bound: 35.26935

Extent Group 8 / Time Frame 1

CC ID: 1297285
Time Frame Type: Range
Start: 2019-12-09
End: 2020-04-28

Extent Group 9

Extent Description:

Block09

Extent Group 9 / Geographic Area 1

CC ID: 1297289
W° Bound: -76.782432
E° Bound: -75.661664
N° Bound: 36.45838
S° Bound: 35.500726

Extent Group 9 / Time Frame 1

CC ID: 1297288
Time Frame Type: Range
Start: 2019-12-04
End: 2020-05-30

Spatial Information

Spatial Representation

Representations Used

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

Reference Systems

Reference System 1

CC ID: 1297262

Coordinate Reference System

CRS Type: Projected
EPSG Code: EPSG:6347
EPSG Name: NAD83(2011) / UTM zone 18N
See Full Coordinate Reference System Information

Access Information

Security Class: Unclassified
Data Access Procedure:

Data is available online for bulk or 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: 1128673
Start Date: 2021-05
End Date: Present
Download URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=9468
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2022 - Present)
File Name: Customized Download
Description:

Create custom data files by choosing data area, product type, map projection, file format, datum, etc. A new metadata will be produced to reflect your request using this record as a base. Change to an orthometric vertical datum is one of the many options.

File Type (Deprecated): Zip
Compression: Zip

Distribution 2

CC ID: 1128674
Start Date: 2020-05
End Date: Present
Download URL: https://noaa-nos-coastal-lidar-pds.s3.us-east-1.amazonaws.com/dem/NGS_VAtoSC_Topobathy_DEM_2020_9468/index.html
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2022 - Present)
File Name: Bulk Download
Description:

Bulk download of data files in LAZ format, geographic coordinates, orthometric heights. Note that the vertical datum (hence elevations) of the files here are different than described in this document. They will be in an orthometric datum.

File Type (Deprecated): LAZ
Distribution Format: LAS/LAZ - LASer
Compression: Zip

URLs

URL 1

CC ID: 1128675
URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/9467/supplemental/extent_ngs_postFlorence_topobathy_m9467.kmz
Name: Browse graphic
URL Type:
Browse Graphic
File Resource Format: KML
Description:

This graphic displays the footprint for this lidar data set.

URL 2

CC ID: 1128676
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.

URL 3

CC ID: 1128677
URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/9467/supplemental/NOAA_Hurricane_Florence_Topobathymetric_LiDAR_and_Shoreline_Mapping_Report_Rev1.pdf
Name: Lidar Report
URL Type:
Online Resource
File Resource Format: pdf
Description:

Link to lidar report

Technical Environment

Description:

OS Independent

Data Quality

Accuracy:

Lidar horizontal accuracy is a function of Global Navigation Satellite System (GNSS) derived positional error, flying altitude, and INS derived attitude error. The obtained RMSEr value is multiplied by a conversion factor of 1.7308 to yield the horizontal component of the National Standards for Spatial Data Accuracy (NSSDA) reporting standard where a theoretical point will fall within the obtained radius 95 percent of the time (ACCr).

Absolute accuracy was assessed using both Non-Vegetated Vertical Accuracy (NVA) and Vegetated Vertical Accuracy (VVA) survey methods. Survey checkpoints were evenly distributed as feasible throughout the project area. NVA compares known ground check point data that were withheld from the calibration and post-processing of the lidar point cloud to the derived gridded bare earth DEM. NVA is a measure of the accuracy of lidar point data in open areas with level slope (less than 20 degrees) where the lidar system has a high probability of measuring the ground surface and is evaluated at the 95% confidence interval (1.96*RMSE). Project specifications require NVA meet 0.196 m accuracy at the 95% confidence interval. Ground check points located in land cover categories other than bare earth, urban, or submerged topography were used to compute the Vegetated Vertical Accuracy (VVA). Project specifications require VVA meet 0.36 m based on the 95th percentile tested against the derived bare earth DEM.

Submerged topography points were tested separately to calculate accuracy and usually occurred in depths up to 1m. Project specifications require submerged topography shall meet a vertical RMSE of QL2b specified in the Draft National Coastal Mapping strategy 1.0 which is equivalent to 0.30 m RMSE at a depth of 1 m. Please refer to the NOAA Hurricane Florence Topobathymetric lidar final data report for final accuracies, to be provided upon project completion.

Horizontal Positional Accuracy:

Block01: Based on a flying altitude of 400 meters, an IMU error of 0.002 decimal degrees, and a GNSS positional error of 0.015 meters, the RMSEr value for the Delivery 1 area is 0.029 meters, with a ACCr of 0.05 meters at the 95% confidence level.

Block02:Based on a flying altitude of 400 meters, an IMU error of 0.005 decimal degrees, and a GNSS positional error of 0.015 meters, the RMSEr value for the Delivery 2 area is 0.064 meters, with a ACCr of 0.11 meters at the 95% confidence level.

Block03:Based on a flying altitude of 400 meters, an IMU error of 0.006 decimal degrees, and a GNSS positional error of 0.015 meters, the RMSEr value for the Delivery 3 area is 0.076 meters, with a ACCr of 0.13 meters at the 95% confidence level. The project specification requires horizontal positions to be accurate to 1.0m(RMSE).

Block04:Based on a flying altitude of 400 meters, an IMU error of 0.003 decimal degrees, and a GNSS positional error of 0.015 meters, the RMSEr value for the Delivery 4 area is 0.040 meters, with a ACCr of 0.07 meters at the 95% confidence level.

Block05: Based on a flying altitude of 400 meters, an IMU error of 0.003 decimal degrees, and a GNSS positional error of 0.015 meters, the RMSEr value for the Delivery 5 area is 0.040 meters, with a ACCr of 0.07 meters at the 95% confidence level.

Block06: Based on a flying altitude of 400 meters, an IMU error of 0.005 decimal degrees, and a GNSS positional error of 0.015 meters, the RMSEr value for the Delivery 6 area is 0.064 meters, with a ACCr of 0.11 meters at the 95% confidence level.

Block07:Based on a flying altitude of 400 meters, an IMU error of 0.005 decimal degrees, and a GNSS positional error of 0.015 meters, the RMSEr value for the Delivery 7 area is 0.064 meters, with a ACCr of 0.11 meters at the 95% confidence level.

Block08: Based on a flying altitude of 400 meters, an IMU error of 0.005 decimal degrees, and a GNSS positional error of 0.015 meters, the RMSEr value for the Delivery 8 area is 0.064 meters, with a ACCr of 0.11 meters at the 95% confidence level.

Block09: Based on a flying altitude of 400 meters, an IMU error of 0.006 decimal degrees, and a GNSS positional error of 0.023 meters, the RMSEr value for the Delivery 9 area is 0.078 meters, with a ACCr of 0.14 meters at the 95% confidence level.

Vertical Positional Accuracy:

All accuracy values are reported at 95% confidence level.

Block01 dataset Non-Vegetated Vertical Accuracy (NVA) tested 0.049 m against the derived bare earth DEM in open terrain using 10 ground check points, based on RMSEz (0.025 m) x 1.9600. Vegetated Vertical Accuracy (VVA) tested 0.164 m at the 95th percentile against the derived bare earth DEM using 9 landclass points. Block01 tested 0.157 m against the derived topobathymetric bare earth DEM using 34 submerged check points, based on RMSEz (0.080 m) x 1.9600.

Block02 dataset NVA tested 0.072 m against the derived bare earth DEM in open terrain using 14 ground check points, based on RMSEz (0.037 m) x 1.9600. VVA tested 0.154 m at the 95th percentile against the derived bare earth DEM using 14 landclass points. Block02 tested 0.116 m vertical accuracy against the derived topobathymetric bare earth DEM using 89 submerged check points, based on RMSEz (0.059 m) x 1.9600.

Block03 dataset NVA tested 0.041 m against the derived bare earth DEM in open terrain using 19 ground check points, based on RMSEz (0.021 m) x 1.9600. VVA tested 0.123 m at the 95th percentile against the derived bare earth DEM using 20 landclass points. Block03 tested 0.174 m vertical accuracy against the derived topobathymetric bare earth DEM using 60 submerged check points, based on RMSEz (0.089 m) x 1.9600.

Block04 dataset NVA tested 0.047 m against the derived bare earth DEM in open terrain using 8 ground check points, based on RMSEz (0.024 m) x 1.9600. VVA tested 0.089 m at the 95th percentile against the derived bare earth DEM using 3 landclass points. Block04 tested 0.140 m vertical accuracy against the derived topobathymetric bare earth DEM using 34 submerged check points, based on RMSEz (0.071 m) x 1.9600.

Block05 dataset NVA tested 0.048 m against the derived bare earth DEM in open terrain using 27 ground check points, based on RMSEz (0.025 m) x 1.9600. VVA tested 0.093 m at the 95th percentile against the derived bare earth DEM using 3 landclass points. Block05 tested 0.160 m vertical accuracy against the derived topobathymetric bare earth DEM using 308 submerged check points, based on RMSEz (0.082 m) x 1.9600.

Block06 dataset NVA tested 0.084 m against the derived bare earth DEM in open terrain using 27 ground check points, based on RMSEz (0.043 m) x 1.9600. VVA tested 0.242 m at the 95th percentile against the derived bare earth DEM using 14 landclass points. Block06 tested 0.195 m vertical accuracy against the derived topobathymetric bare earth DEM using 165 submerged check points, based on RMSEz (0.100 m) x 1.9600.

Block07 dataset NVA tested 0.049 m against the derived bare earth DEM in open terrain using 24 ground check points, based on RMSEz (0.025 m) x 1.9600. VVA tested 0.195 m at the 95th percentile against the derived bare earth DEM using 17 landclass points. Block07 tested 0.144 m vertical accuracy against the derived topobathymetric bare earth DEM using 124 submerged check points, based on RMSEz (0.074 m) x 1.9600.

Block08 dataset NVA tested 0.068 m against the derived bare earth DEM in open terrain using 23 ground check points, based on RMSEz (0.034 m) x 1.9600. VVA tested 0.197 m at the 95th percentile against the derived bare earth DEM using 22 landclass points. Block08 tested 0.135 m vertical accuracy against the derived topobathymetric bare earth DEM using 123 submerged check points, based on RMSEz (0.069 m) x 1.9600.

Block09 dataset NVA tested 0.067 m against the derived bare earth DEM in open terrain using 34 ground check points, based on RMSEz (0.034 m) x 1.9600. VVA tested 0.159 m at the 95th percentile against the derived bare earth DEM using 18 landclass points. Block09 tested 0.244 m vertical accuracy against the derived topobathymetric bare earth DEM using 11 submerged check points, based on RMSEz (0.124 m) x 1.9600.

Completeness Measure:

Block01 is comprised of 36 - 5000 m x 5000 m DEM tiles.

Block02 is comprised of 77 - 5000 m x 5000 m DEM tiles.

Block03 is comprised of 107 - 5000 m x 5000 m DEM tiles.

Block04 is comprised of 61 - 5000 m x 5000 m DEM tiles.

Block05 is comprised of 62 - 5000 m x 5000 m DEM tiles.

Block06 is comprised of 79 - 5000 m x 5000 m DEM tiles.

Block07 is comprised of 101 - 5000 m x 5000 m DEM tiles.

Block08 is comprised of 126 - 5000 m x 5000 m DEM tiles..

Block09 is comprised of 175 - 5000 m x 5000 m DEM tiles..

Conceptual Consistency:

Not applicable

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-CO
How Will the Data Be Protected from Accidental or Malicious Modification or Deletion Prior to Receipt by the Archive?:

Data is backed up to tape and to cloud storage.

Lineage

Sources

Acquisition and Processing

CC ID: 1297257
Contact Role Type: Originator
Contact Type: Organization
Contact Name: NV5 Geospatial, Inc

Process Steps

Process Step 1

CC ID: 1297258
Description:

Data for the NOAA Florence Topobathymetric Lidar project area was acquired by NV5 Geospatial (NV5). All derived DEMdata is referenced to:

Horizontal Datum-NAD83(2011) epoch: 2010.00

Projection-UTM Zone 18N

Horizontal Units-meters

Vertical Datum-NAVD88 (Geoid18)

Vertical Units-meters

The collected lidar data were immediately processed in the field by NV5 to a level that will allow QA\QC measures to determine if the sensor is functioning properly and assess the coverage of submerged topography. An initial SBET was created in POSPAC MMS 8.3 SP3 and loaded into RiProcess which applies pre-calibrated angular misalignment corrections of scanner position to extract the raw point cloud into geo-referenced LAS files. These files were inspected for sensor malfunctions and then passed through automated raster generation using LAStools to develop an initial assessment of bathymetric coverage. NV5 reviewed all acquired flight lines to ensure complete coverage and positional accuracy of the laser points. These rasters were also used to create an initial product in Quick Look Coverage Maps. These Quick Look files are not fully processed data or final products but provide rapid assessment of approximate coverage and depth penetration.

NV5 resolved kinematic corrections for aircraft position data using aircraft GNSS and Applanix's proprietary PP-RTX solution. When PP-RTX was not used NV5 conducted static Global Navigation Satellite System (GNSS) ground surveys (1 Hz recording frequency) using base stations over known monument locations during flights. After the airborne survey, static GPS data were triangulated with nearby Continuously Operating Reference Stations (CORS) using the Online Positioning User Service (OPUS) for precise positioning. Multiple independent sessions over the same base station were performed to confirm antenna height measurements and to refine position accuracy. This data was used to correct the continuous on board measurements of the aircraft position recorded throughout the flight. A final smoothed best estimate trajectory (SBET) was developed that blends post-processed aircraft position with attitude data. Using the SBETs, sensor head position and attitude were then calculated throughout the survey. Trimble Business Center v.3.90, Blue Marble Geographic Calculator 2019, and PosPac MMS 8.3 SP3 were used for these processes.

Process Date/Time: 2020-10-02 00:00:00
Process Contact: NGS Communications and Outreach Branch
Phone (Voice): (301) 713-3242
Email Address: ngs.infocenter@noaa.gov

Process Step 2

CC ID: 1297259
Description:

Following final SBET creation, NV5 used RiProcess 1.8.5 to calculate laser point positioning by associating SBET positions to each laser point return time, scan angle, and intensity. Terra 19 and LasTools were used to classify water surface and create a water surface model. They are created for single swaths to ensure temporal differences and wave or water surface height variations between flight lines do not impact the refraction of the bathymetric data. These models are used in NV5's LasMonkey refraction tool to determine the accurate positioning of bathymetric points. All lidar data below water surface models were classified as water column to be refracted. Light travels at different speeds in air versus water and its direction of travel or angle is changed or refracted when entering the water column. The refraction tool corrects for this difference by adjusting the depth (distance traveled) and horizontal positioning (change of angle/direction) of the lidar data. Using raster-based QC methods, the output data is verified to ensure the refraction tool functioned properly.

In addition, for Blocks 4 - 7, following final SBET creation for the Leica Chiroptera 4X and Hawkeye systems, NV5 used Leica Lidar Survey Studio (LSS) to calculate laser point positioning by associating SBET positions to each laser point return time, scan angle, and intensity. Leica LSS was used to derive a synthetic water surface to create a water surface model. Light travels at different speeds in air versus water and its direction of travel or angle is changed or refracted when entering the water column. The refraction tool corrects for this difference by adjusting the depth (distance traveled) and horizontal positioning (change of angle/direction) of the lidar data. All lidar data below water surface models were classified as water column to correct for refraction. Using raster-based QC methods, the output data is verified to ensure the refraction tool functioned properly.

Process Date/Time: 2020-12-17 00:00:00
Process Contact: National Geodetic Survey (NGS)

Process Step 3

CC ID: 1297260
Description:

Once all data was refracted by flight line data was exported to LAS 1.4 format and combined into 500 m x 500 m tiles. Data were then further calibrated using TerraMatch. NV5 used custom algorithms in TerraScan to classify the initial ground/submerged topography surface points. Relative accuracy of overlapping swaths was compared and verified through the use Delta-Z (DZ) orthos created using NV5's Las Product Creator. Absolute vertical accuracy of the calibrated data was assessed using ground survey data and complete coverage was again verified.

Post automated classification NV5 then performed manual editing to review all classification and improve the final topobathymetric surface. NV5's LasMonkey 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.

The delivered dataset used the following classification scheme for Block01, Block02, Block03, Block08 and Block09:

1 - Unclassified

2 - Ground

7 - Noise

40 - Bathymetric Bottom or Submerged Topography

41 - Water Surface

43 - Submerged feature

45 - Water Column

46 - Temporal Bathymetric Bottom

71 - Overlap Default

72 - Overlap Ground

81 - Overlap Water Surface

85 - Overlap Water Column

1-Overlap - Edge Clip

The delivered dataset used the following classification scheme for Block04, Block05, Block06 and Block07:

1 - unclassified

2 - ground

7 - noise

40 - bathymetric bottom or submerged topography

41 - water surface

42 Synthetic- Chiroptera synthetic water surface

43 - submerged feature

45 - water column

46 - overlap bathy bottom - temporally different from a separate lift

71 - unclassified associated with areas of overlap bathy bottom/temporal bathymetric differences

72 - ground associated with areas of overlap bathy bottom/temporal bathymetric differences

81 - water surface associated with areas of overlap bathy bottom/temporal bathymetric differences

81 Synthetic - Chiroptera synthetic water surface associated with areas of overlap bathy bottom/temporal bathymetric differences

85 - water column associated with areas of overlap bathy bottom/temporal bathymetric differences

1 Overlap - edge clip

1 Withheld - unrefracted green data from Chiroptera sensor

Process Date/Time: 2022-01-29 00:00:00
Process Contact: National Geodetic Survey (NGS)

Process Step 4

CC ID: 1297261
Description:

NV5 transformed the final LiDAR data from ellipsoid heights to orthometric heights referenced to NAVD88, Geoid 18 to create the final topobathymetric void clipped DEMs. The topobathymetric bare earth DEMs were output at 1 meter resolution in GeoTIFF format into 5000 m x 5000 m tiles. The rasters are clipped to the extent of the project boundary and named according to project specifications.

A bathymetric void shapefile was created to indicate areas where there was a lack of bathymetric returns. This shape was created by triangulating bathymetric bottom points with an edge length maximum of 4.56m to identify all areas greater then 9 square meters without bathymetric returns. This shapefile was used to clip and exclude interpolated elevation data from these areas in the bathymetric void clipped topobathymetric bare earth model.

Process Date/Time: 2020-10-02 00:00:00
Process Contact: National Geodetic Survey (NGS)

Catalog Details

Catalog Item ID: 66714
GUID: gov.noaa.nmfs.inport:66714
Metadata Record Created By: Maryellen Sault
Metadata Record Created: 2022-03-02 18:20+0000
Metadata Record Last Modified By: Kirk Waters
Metadata Record Last Modified: 2024-01-10 19:23+0000
Metadata Record Published: 2024-01-10
Owner Org: NGS
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Last Review Date: 2022-03-15
Metadata Review Frequency: 1 Year
Metadata Next Review Date: 2023-03-15