2021 NOAA NGS Topobathy Lidar: Revillagigedo Channel, Southeast Alaska
Data Set (DS) | National Geodetic Survey (NGS)GUID: gov.noaa.nmfs.inport:69818 | Updated: October 17, 2023 | Published / External
Summary
Short Citation
National Geodetic Survey, 2024: 2021 NOAA NGS Topobathy Lidar: Revillagigedo Channel, Southeast Alaska, https://www.fisheries.noaa.gov/inport/item/69818.
Full Citation Examples
NOAA Southeast AK Topobathymetric Lidar data were collected by NV5 Geospatial (NV5) using Leica Hawkeye 4X and Riegl 1560i systems and delivered to NOAA in four blocks. The NOAA Southeast AK Topobathymetric Lidar Block01 was acquired between 20210608 and 20210730 in 13 missions, Block02 was acquired between 20210611 and 20210730 in 14 missions, Block03 was acquired between 20210730 and 20210823 in 6 mission and Block 04 was acquired between 20210625 and 20210823 in 7 missions. The four block dataset includes topobathymetric data in a LAS format 1.4, point data record format 6, with the following classifications in accordance with project specifications and the American Society for Photogrammetry and Remote Sensing (ASPRS) classification standards:
1 - unclassified
2 - ground
7 Withheld -low noise
18 Withheld - high noise
40 - bathymetric bottom or submerged topography
41 - water surface
42 Synthetic- Chiroptera synthetic water surface
43 - submerged feature
45 - water column
64 - Submerged Aquatic Vegetation (SAV)
65 - 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
82 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 Withheld - edge clip
1 Overlap Withheld - unrefracted green data from Chiroptera sensor
The channel bits are as follows:
0 - Riegl VQ1560 NIR channel A and Chiroptera green shallow laser
1 - Riegl VQ1560 NIR channel B and Chiroptera/Hawkeye synthetic water surface
2 - Hawkeye green deep laser
3 - Chiroptera NIR
The user byte is mapped as the following:
0 - Riegl NIR channel A
1 - Riegl NIR channel B
10 - Chiroptera green shallow
11 - Chiroptera green shallow 4X
12 - Chiroptera green shallow synthetic
20 - Hawkeye green deep
21 - Hawkeye green deep 4X
22 - Hawkeye green deep synthetic
30 - Chiroptera NIR
Data in all blocks includes lidar intensity values, number of returns, return number, time, and scan angle. The block01 boundary extent covers 103,002 acres , the Block02 boundary extent covers 76,119 acres, the block03 boundary extent covers 55,929 acres and Block04 boundary extent covers 18,351 acres of the combined topographic and bathymetric project boundaries.
After the initial Southeast AK Topobathymetric Lidar submission, NOAA reviewed the data and provided NV5 Geospatial with a feedback edit review. NV5 Geospatial has corrected these feedback edits and incorporated them into the final block datasets. Additionally, green laser intensity values were normalized for depth for the dataset resulting in a full redelivery of all LAS files. LAS files were compiled in 500 m x 500 m tiles.
Distribution Information
-
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.
-
LAS/LAZ - LASer
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.
None
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.
Controlled Theme Keywords
COASTAL BATHYMETRY, COASTAL ELEVATION, elevation, Elevation Theme, TERRAIN ELEVATION
Child Items
Type | Title |
---|---|
Entity | NOAA NGS Topobathy Lidar Class Scheme: evillagigedo Channel, Southeast Alaska |
Contact Information
Metadata Contact
NOAA Office for Coastal Management (NOAA/OCM)
coastal.info@noaa.gov
(843) 740-1202
https://coast.noaa.gov
Extents
-131.683084° W,
-131.14722° E,
55.153375° N,
54.797478° S
2021-06-08 - 2021-07-30
Item Identification
Title: | 2021 NOAA NGS Topobathy Lidar: Revillagigedo Channel, Southeast Alaska |
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Status: | Completed |
Publication Date: | 2023 |
Abstract: |
NOAA Southeast AK Topobathymetric Lidar data were collected by NV5 Geospatial (NV5) using Leica Hawkeye 4X and Riegl 1560i systems and delivered to NOAA in four blocks. The NOAA Southeast AK Topobathymetric Lidar Block01 was acquired between 20210608 and 20210730 in 13 missions, Block02 was acquired between 20210611 and 20210730 in 14 missions, Block03 was acquired between 20210730 and 20210823 in 6 mission and Block 04 was acquired between 20210625 and 20210823 in 7 missions. The four block dataset includes topobathymetric data in a LAS format 1.4, point data record format 6, with the following classifications in accordance with project specifications and the American Society for Photogrammetry and Remote Sensing (ASPRS) classification standards: 1 - unclassified 2 - ground 7 Withheld -low noise 18 Withheld - high noise 40 - bathymetric bottom or submerged topography 41 - water surface 42 Synthetic- Chiroptera synthetic water surface 43 - submerged feature 45 - water column 64 - Submerged Aquatic Vegetation (SAV) 65 - 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 82 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 Withheld - edge clip 1 Overlap Withheld - unrefracted green data from Chiroptera sensor
The channel bits are as follows: 0 - Riegl VQ1560 NIR channel A and Chiroptera green shallow laser 1 - Riegl VQ1560 NIR channel B and Chiroptera/Hawkeye synthetic water surface 2 - Hawkeye green deep laser 3 - Chiroptera NIR
The user byte is mapped as the following: 0 - Riegl NIR channel A 1 - Riegl NIR channel B 10 - Chiroptera green shallow 11 - Chiroptera green shallow 4X 12 - Chiroptera green shallow synthetic 20 - Hawkeye green deep 21 - Hawkeye green deep 4X 22 - Hawkeye green deep synthetic 30 - Chiroptera NIR Data in all blocks includes lidar intensity values, number of returns, return number, time, and scan angle. The block01 boundary extent covers 103,002 acres , the Block02 boundary extent covers 76,119 acres, the block03 boundary extent covers 55,929 acres and Block04 boundary extent covers 18,351 acres of the combined topographic and bathymetric project boundaries. After the initial Southeast AK Topobathymetric Lidar submission, NOAA reviewed the data and provided NV5 Geospatial with a feedback edit review. NV5 Geospatial has corrected these feedback edits and incorporated them into the final block datasets. Additionally, green laser intensity values were normalized for depth for the dataset resulting in a full redelivery of all LAS files. LAS files were compiled in 500 m x 500 m tiles. |
Purpose: |
This lidar data was required by National Oceanic and Atmospheric Administration (NOAA), 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: |
The topobathymetric lidar data 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. The automated grounding was followed with manual editing. Classes 2 (ground), 40 (submerged topography), 43 (submerged object), and 64 (Submerged aquatic vegetation) were used to create the final DEMs. The full workflow used for this project is documented in the NOAA Finger Lakes Topobathymetric Lidar final report and is available upon request. |
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 > OCEANS > BATHYMETRY/SEAFLOOR TOPOGRAPHY > BATHYMETRY > COASTAL BATHYMETRY
|
Global Change Master Directory (GCMD) Science Keywords |
EARTH SCIENCE > OCEANS > COASTAL PROCESSES > COASTAL ELEVATION
|
ISO 19115 Topic Category |
elevation
|
NGDA Portfolio Themes |
Elevation Theme
|
Spatial Keywords
Thesaurus | Keyword |
---|---|
Global Change Master Directory (GCMD) Location Keywords |
CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA > ALASKA
|
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 |
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City: | Charleston |
State/Province: | SC |
Data Set Information
Data Set Scope Code: | Data Set |
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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
Date Effective From: | 2023 |
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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
Date Effective From: | 2023 |
---|---|
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
Date Effective From: | 2023 |
---|---|
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
Date Effective From: | 2023 |
---|---|
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 |
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Extent Group 1
Extent Group 1 / Geographic Area 1
W° Bound: | -131.683084 | |
---|---|---|
E° Bound: | -131.14722 | |
N° Bound: | 55.153375 | |
S° Bound: | 54.797478 |
Extent Group 1 / Time Frame 1
Time Frame Type: | Range |
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Start: | 2021-06-08 |
End: | 2021-07-30 |
Extent Group 2
Extent Description: |
Work in progress |
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Extent Group 2 / Geographic Area 1
W° Bound: | -131.817401 | |
---|---|---|
E° Bound: | -131.114438 | |
N° Bound: | 55.392168 | |
S° Bound: | 55.059655 |
Extent Group 2 / Time Frame 1
Time Frame Type: | Range |
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Start: | 2021-06-11 |
End: | 2021-07-30 |
Extent Group 3
Extent Group 3 / Geographic Area 1
W° Bound: | -131.122052 | |
---|---|---|
E° Bound: | -130.70137 | |
N° Bound: | 55.223374 | |
S° Bound: | 54.745594 |
Extent Group 3 / Time Frame 1
Time Frame Type: | Range |
---|---|
Start: | 2021-07-30 |
End: | 2021-08-23 |
Extent Group 4
Extent Group 4 / Geographic Area 1
W° Bound: | -131.132875 | |
---|---|---|
E° Bound: | -130.713203 | |
N° Bound: | 55.425577 | |
S° Bound: | 55.208082 |
Extent Group 4 / Time Frame 1
Time Frame Type: | Range |
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Start: | 2021-06-25 |
End: | 2021-08-23 |
Spatial Information
Spatial Representation
Representations Used
Grid: | No |
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Vector: | Yes |
Text / Table: | No |
TIN: | No |
Stereo Model: | No |
Video: | No |
Reference Systems
Reference System 1
Coordinate Reference System |
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Access Information
Security Class: | Unclassified |
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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
Start Date: | 2021-05 |
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End Date: | Present |
Download URL: | https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=9833 |
Distributor: | NOAA Office for Coastal Management (NOAA/OCM) (2023 - 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
Start Date: | 2020-05 |
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End Date: | Present |
Download URL: | https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/9833/index.html |
Distributor: | NOAA Office for Coastal Management (NOAA/OCM) (2023 - 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
URL: | https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/9833/supplemental/extent_ngs_SE_ak__2021_m9833.kmz |
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Name: | Browse graphic |
URL Type: |
Browse Graphic
|
File Resource Format: | KML |
Description: |
This graphic displays the footprint for this lidar data set. |
URL 2
URL: | https://coast.noaa.gov/dataviewer/ |
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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: |
OS Independent |
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Data Quality
Horizontal Positional 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). The project specification requires horizontal positions to be accurate to 1.0m(RMSE). Block01 and Block02: Based on a flying altitude of 500 meters, an IMU error of 0.002 decimal degrees, and a GNSS positional error of 0.008 meters, the RMSEr value for the Leica Chiroptera shallow green and NIR sensor data in the Block01 area is 0.032 meters, with a ACCr of 0.06 meters at the 95% confidence level. The RMSEr value for the Leica Hawkeye deep green sensor data in the Block01 area is 0.032 meters, with a ACCr of 0.06 meters at the 95% confidence level based on a flying altitude of 500 meters, an IMU error of 0.002 decimal degrees, and a GNSS positional error of 0.008 meters. Additionally, based on a flying altitude of 1995 meters, an IMU error of 0.001 decimal degrees, and a GNSS positional error of 0.019 meters, the RMSEr value for the Riegl 1560i NIR sensor data in the Block01 area is 0.065 meters, with a ACCr of 0.06 meters at the 95% confidence level. Block03: Based on a flying altitude of 500 meters, an IMU error of 0.002 decimal degrees, and a GNSS positional error of 0.005 meters, the RMSEr value for the Leica Chiroptera shallow green and NIR sensor data in the Block03 area is 0.032 meters, with a ACCr of 0.05 meters at the 95% confidence level. The RMSEr value for the Leica Hawkeye deep green sensor data in the Block03 area is 0.032 meters, with a ACCr of 0.06 meters at the 95% confidence level based on a flying altitude of 500 meters, an IMU error of 0.002 decimal degrees, and a GNSS positional error of 0.008 meters. Additionally, based on a flying altitude of 1995 meters, an IMU error of 0.002 decimal degrees, and a GNSS positional error of 0.019 meters, the RMSEr value for the Riegl 1560i NIR sensor data in the Block03 area is 0.126 meters, with a ACCr of 0.22 meters at the 95% confidence level. Block04: Based on a flying altitude of 500 meters, an IMU error of 0.002 decimal degrees, and a GNSS positional error of 0.005 meters, the RMSEr value for the Leica Chiroptera shallow green and NIR sensor data in the Block04 area is 0.032 meters, with a ACCr of 0.05 meters at the 95% confidence level. The RMSEr value for the Leica Hawkeye deep green sensor data in the Block04 area is 0.032 meters, with a ACCr of 0.05 meters at the 95% confidence level based on a flying altitude of 500 meters, an IMU error of 0.002 decimal degrees, and a GNSS positional error of 0.005 meters. Additionally, based on a flying altitude of 1995 meters, an IMU error of 0.002 decimal degrees, and a GNSS positional error of 0.019 meters, the RMSEr value for the Riegl 1560i NIR sensor data in the Delivery 4 area is 0.126 meters, with a ACCr of 0.22 meters at the 95% confidence level. |
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Vertical Positional Accuracy: |
Absolute accuracy was assessed using Non-Vegetated Vertical Accuracy (NVA) survey methods. Survey check points 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 triangulated surface generated by the unclassified lidar point cloud. NVA is a measure of the accuracy of lidar point data in open areas with level slope (less than 20°) 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. Please refer to the NOAA Southeast AK Topobathymetric Lidar final data report for final accuracies, available upon request. The Block01 area dataset Non-Vegetated Vertical Accuracy tested 0.035 m vertical accuracy at the 95% confidence level against the unclassified lidar point cloud in open terrain using 9 ground survey check points, based on RMSEz (0.018 m) x 1.9600. The Block02 area dataset Non-Vegetated Vertical Accuracy tested 0.036 m vertical accuracy at the 95% confidence level against the unclassified lidar point cloud in open terrain using 16 ground check points, based on RMSEz (0.018 m) x 1.9600. The Block03 area dataset Non-Vegetated Vertical Accuracy tested 0.091 m vertical accuracy at the 95% confidence level against the ground classified lidar point cloud in open terrain using 19 ground check points, based on RMSEz (0.046 m) x 1.9600. The Block04 area dataset Non-Vegetated Vertical Accuracy tested 0.054 m vertical accuracy at the 95% confidence level against the ground classified lidar point cloud in open terrain using 9 ground check points, based on RMSEz (0.028 m) x 1.9600. |
Completeness Report: |
Data covers the project boundary. |
Conceptual Consistency: |
Not applicable |
Data Management
Have Resources for Management of these Data Been Identified?: | Yes |
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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
Contact Role Type: | Originator |
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Contact Type: | Organization |
Contact Name: | NV5 |
Process Steps
Process Step 1
Description: |
Data for the block areas were acquired by NV5 Geospatial (NV5) using Leica Hawkeye 4X and Riegl VQ-1560i topobathymetric lidar systems. All derived LAS data is referenced to: Horizontal Datum-NAD83(2011) epoch: 2010.00 Projection-UTM Zone 9N Horizontal Units-meters Vertical Datum-GRS80 Ellipsoid Vertical Units-meters NOAA provided NV5 Geospatial with a bathymetric boundary and a topographic boundary for the NOAA Southeast AK Topobathymetric Lidar project. Two separate acquisition plans were made; one for the bathymetric boundary and one for the topographic lidar boundary. The bathymetric areas for Block01 and Block02 were acquired using a Leica Hawkeye 4X topobathymetric sensor while Block03 and Block04 were acquired using a Leica Chiroptera Hawkeye 4X topobathymetric sensor. The topographic area in Block01 and Block02 was acquired using a Riegl 1560i NIR sensor while Block03 and Block04 was acquired using a Riegl VQ-1560ii NIR sensor. The data were integrated and calibrated together into a singular dataset after the initial extractions. A cutline was drawn through the project area to prioritize the bathymetric data and to produce the smoothest and most cohesive integrated dataset. A more detailed description of data processing is outlined below. 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 using Waypoint Inertial Explorer 8.90, and the raw data were extracted into geo-referenced LAS files using Lidar Survey Studio 3.0 with pre-calculated scanner misalignment angles determined through a boresight protocol. These files were inspected for errors and then passed through an automated workflow, producing rasters 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. |
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Process Date/Time: | 2022-06-23 00:00:00 |
Process Contact: | NGS Communications and Outreach Branch |
Phone (Voice): | (301) 713-3242 |
Email Address: | ngs.infocenter@noaa.gov |
Process Step 2
Description: |
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. 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. In addition, following final SBET creation for the Reigl VQ1560i sensor data, 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. Using raster-based QC methods, the output data is verified to ensure the refraction tool functioned properly. 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. |
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Process Date/Time: | 2022-06-23 00:00:00 |
Process Contact: | National Geodetic Survey (NGS) |
Process Step 3
Description: |
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 final classification scheme is as follows: 1 - unclassified 2 - ground 7 Withheld -low noise 18 Withheld - high noise 40 - bathymetric bottom or submerged topography 41 - water surface 42 Synthetic- Chiroptera synthetic water surface 43 - submerged feature 45 - water column 64 - Submerged Aquatic Vegetation (SAV) 65 - 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 82 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 Withheld - edge clip 1 Overlap Withheld - unrefracted green data from Chiroptera sensor |
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Process Date/Time: | 2022-06-23 00:00:00 |
Process Step 4
Description: |
The NOAA Office for Coastal Management (OCM) received files in laz format. The files contained lidar elevation and intensity measurements. The data were in UTM Zone 9 coordinates and ellipsoid elevations in meters. OCM performed the following processing on the data for Digital Coast storage and provisioning purposes: 1. Converted from UTM Zone 9 to geographic coordinates 2. Sorted by gps time. Additionally, some point classifications were changed in order to conform to the topobathy domain profile standards. The final class list on the Digital Coast is as follows: Class List and Point count: 1 : 39071363453 2 : 2959736792 7 : 830465252 18 : 35748976 20 : 850775 22 : 1338043162 40 : 349113802 41 : 593184971 42 : 8220130553 43 : 54 45 : 3812489090 46 : 7459945 47 : 2386246 48 : 5575275558 Where Class 64 was moved to 46 (Submerged Vegetation) Class 65 was moved to 20 (Possible Ground) Classes 71 & 81 were moved to 48 (Submerged Temporal Exclusion) Class 72 was moved to 22 (Temporal exclusion) 82 was moved to class 1 (Unclassified) 85 was moved to 47 (submerged noise) |
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Process Contact: | Office for Coastal Management (OCM) |
Child Items
Rubric scores updated every 15m
Type | Title | |
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Entity | NOAA NGS Topobathy Lidar Class Scheme: evillagigedo Channel, Southeast Alaska |
Catalog Details
Catalog Item ID: | 69818 |
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GUID: | gov.noaa.nmfs.inport:69818 |
Metadata Record Created By: | Maryellen Sault |
Metadata Record Created: | 2023-05-03 15:29+0000 |
Metadata Record Last Modified By: | SysAdmin InPortAdmin |
Metadata Record Last Modified: | 2023-10-17 16:12+0000 |
Metadata Record Published: | 2023-06-21 |
Owner Org: | NGS |
Metadata Publication Status: | Published Externally |
Do Not Publish?: | N |
Metadata Last Review Date: | 2022-03-16 |
Metadata Review Frequency: | 3 Years |
Metadata Next Review Date: | 2025-03-16 |