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Short Citation:
OCM Partners, 2024: 2019 USGS Topobathy Lidar: Potomac River, MD, https://www.fisheries.noaa.gov/inport/item/70734.

Item Identification

Title: 2019 USGS Topobathy Lidar: Potomac River, MD
Short Name: md2019_potomac_tb_m9892_metadata
Status: Completed
Creation Date: 2019
Publication Date: 2020-03-31
Abstract:

Product: These lidar data are processed Classified LAS 1.4 files, formatted to 247 individual 1000 m x 1000 m tiles; used to create intensity images, land/water interface breaklines and topobathymetric DEMs as necessary.

Geographic Extent: Potomac River and margins in Maryland, West Virginia, and Virginia, covering approximately 39.2 square miles.

Dataset Description: The Maryland Potomac River 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 0.7 meter. Project specifications are based on the U.S. Geological Survey National Geospatial Program Base Lidar Specification, version 1.3. The data was developed based on a horizontal projection/datum of NAD83 (2011), Universal Transverse Mercator zone 18, meters and vertical datum of NAVD88 (GEOID12B), meters. Lidar data was delivered as processed Classified LAS 1.4 files, formatted to 247 individual 1000 m x 1000 m tiles, as tiled Intensity Imagery, and as tiled topobathymetric DEMs; all tiled to the same 1000 m x 1000 m schema. A merged topobathymetric DEM was also delivered.

Ground Conditions: Lidar was collected in October 2019, 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 a total of 39 checkpoints that were used to calibrate the lidar to known ground locations established the project area and assess the vertical accuracy of the data.

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, Breaklines and Raster DEM. The purpose of these lidar data was to produce high accuracy 3D hydro-flattened Digital Elevation Model (DEM) with a 1 meter cell size. These lidar point cloud data were used to create intensity images, 3D breaklines, and hydro-flattened DEMs as necessary.

Supplemental Information:

USGS Contract No. G16PC00020

CONTRACTOR: Dewberry Engineers

SUBCONTRACTOR: IIC Technologies

Lidar data were acquired and calibrated by IIC. All follow-on processing was completed by the prime contractor. A complete description of this dataset is available in the Final Project Report that was submitted to the U.S. Geological Survey.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "USGS-NGP Lidar Base Specification V1.3",

"ldrsens" : "Leica Hawkeye 4X (Topo Channels)",

"ldrmaxnr" : "15",

"ldrnps" : "0.35",

"ldrdens" : "8",

"ldranps" : "0.35",

"ldradens" : "8",

"ldrfltht" : "400",

"ldrfltsp" : "140",

"ldrscana" : "40",

"ldrscanr" : "140",

"ldrpulsr" : "500",

"ldrpulsd" : "Unreported",

"ldrpulsw" : "Unreported",

"ldrwavel" : "1064",

"ldrmpia" : "0",

"ldrbmdiv" : "0.5",

"ldrswatw" : "280",

"ldrswato" : "30",

"ldrcrs" : "NAD 1983 (2011) UTM Zone 18 Meters",

"ldrgeoid" : "National Geodetic Survey (NGS) Geoid12B"

},

"ldrinfo" : {

"ldrspec" : "USGS-NGP Lidar Base Specification V1.3",

"ldrsens" : "Leica Hawkeye 4X (Shallow/Deep Bathy Channels)",

"ldrmaxnr" : "15",

"ldrnps" : "0.71",

"ldrdens" : "2",

"ldranps" : "0.71",

"ldradens" : "2",

"ldrfltht" : "400",

"ldrfltsp" : "140",

"ldrscana" : "40",

"ldrscanr" : "140",

"ldrpulsr" : "35/10",

"ldrpulsd" : "Unreported",

"ldrpulsw" : "Unreported",

"ldrwavel" : "515",

"ldrmpia" : "0",

"ldrbmdiv" : "4",

"ldrswatw" : "280",

"ldrswato" : "30",

"ldrcrs" : "NAD 1983 (2011) UTM Zone 18 Meters",

"ldrgeoid" : "National Geodetic Survey (NGS) Geoid12B"

},

"ldraccur" : {

"ldrchacc" : "0",

"rawnva" : "0",

"rawnvan" : "0",

"clsnva" : "0",

"clsnvan" : "0",

"clsvva" : "0",

"clsvvan" : "0"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "6",

"laswheld" : "Withheld points were identified in these files using the standard LAS Withheld bit",

"lasolap" : "The LAS overlap bit was not utilized for this dataset",

"lasintr" : "16",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Processed, Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Bare Earth, Ground"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Low Noise"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridge Deck"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "High Noise"

},

"lasclass" : {

"clascode" : "40",

"clasitem" : "Bathymetric Point"

},

"lasclass" : {

"clascode" : "41",

"clasitem" : "Water Surface"

},

"lasclass" : {

"clascode" : "42",

"clasitem" : "Synthetic Water surface"

},

"lasclass" : {

"clascode" : "45",

"clasitem" : "Water Column"

}

}}

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 > COASTAL PROCESSES > COASTAL ELEVATION
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 > MARYLAND
Global Change Master Directory (GCMD) Location Keywords
CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA > VIRGINIA
Global Change Master Directory (GCMD) Location Keywords
CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA > WEST VIRGINIA
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: U.S. Geological Survey

Support Roles

Data Steward

CC ID: 1270242
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

Distributor

CC ID: 1270241
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

CC ID: 1270243
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

Point of Contact

CC ID: 1270244
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

Extents

Currentness Reference: Ground Condition

Extent Group 1

Extent Group 1 / Geographic Area 1

CC ID: 1270247
W° Bound: -77.805817
E° Bound: -77.115929
N° Bound: 39.457914
S° Bound: 38.918843

Extent Group 1 / Time Frame 1

CC ID: 1270246
Time Frame Type: Range
Start: 2019-10-21
End: 2019-10-26

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: 1270237

Coordinate Reference System

CRS Type: Geographic 3D
EPSG Code: EPSG:6319
EPSG Name: NAD83(2011)
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: 1270248
Start Date: 2023-09-01
End Date: Present
Download URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=9892/details/9892
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

CC ID: 1270249
Start Date: 2023-09-01
End Date: Present
Download URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/9892/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

URLs

URL 1

CC ID: 1270239
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 2

CC ID: 1270683
URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid18/9892/supplemental/il2019_potomac_m9892.kmz
Name: Browse Graphic
URL Type:
Browse Graphic
File Resource Format: kmz
Description:

This graphic displays the footprint for this lidar data set.

URL 3

CC ID: 1270684
URL: https://rockyweb.usgs.gov/vdelivery/Datasets/Staged/Elevation/metadata/MD_PotomacRiverTopoBathy_2019_D19/MD_PotomacRiver_Bathy_2019/
Name: USGS Additional Info
URL Type:
Online Resource
Description:

Link to the reports, metadata, breaklines, and spatial metadata.

URL 4

CC ID: 1270685
URL: https://rockyweb.usgs.gov/vdelivery/Datasets/Staged/Elevation/metadata/MD_PotomacRiverTopoBathy_2019_D19/MD_PotomacRiver_Bathy_2019/reports/Potomac_Lidar_Project_Report_USGS.pdf
Name: Lidar Report
URL Type:
Online Resource
File Resource Format: pdf
Description:

Link to the Dewberry lidar report

URL 5

CC ID: 1270686
URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/entwine/geoid18/9892/ept.json
Name: Entwine Point Tile (EPT)
URL Type:
Online Resource
File Resource Format: json
Description:

Entwine Point Tile (EPT) is a simple and flexible octree-based storage format for point cloud data. The data is organized in such a way that the data can be reasonably streamed over the internet, pulling only the points you need. EPT files can be queried to return a subset of the points that give you a representation of the area. As you zoom further in, you are requesting higher and higher densities. A dataset in EPT will contain a lot of files, however, the ept.json file describes all the rest. The EPT file can be used in Potree and QGIS to view the point cloud.

URL 6

CC ID: 1270687
URL: https://coast.noaa.gov/lidar/viewer/v/noaapotree.html?r=https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/entwine/geoid18/9892/ept.json
Name: Potree 3D View
URL Type:
Online Resource
Description:

Link to view the point cloud (using the Entwine Point Tile (EPT) format) in the 3D Potree viewer.

Technical Environment

Description:

Leica LSS; Bayesmap; LAStools; Microstation; Terrascan; ArcGIS 10.x; Microsoft Windows 10 Enterprise Service Pack 1

Data Quality

Horizontal Positional Accuracy:

Six checkpoints were determined to be photo-identifiable in the intensity imagery and were used to test the horizontal accuracy of the lidar dataset. As only six checkpoints were photo-identifiable, the results are not statistically significant enough to report as a final tested value. Using NSSDA methodology (endorsed by the ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014)), horizontal accuracy at the 95% confidence level (called ACCURACYr) is computed by the formula RMSEr * 1.7308 or RMSExy * 2.448. No horizontal accuracy requirements or thresholds were provided for this project. However, lidar datasets are generally calibrated by methods designed to ensure a horizontal accuracy of 1 meter or less at the 95% confidence level.

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. Six checkpoints were photoidentifiable but do not produce a statistically significant tested horizontal accuracy value. Using this small sample set of photo-identifiable checkpoints, positional accuracy of this dataset was found to be RMSEx = 28.5 cm and RMSEy = 38.5 cm which equates to +/- 82.8 cm at 95% confidence level. While not statistically significant, the results of the small sample set of checkpoints are within the produced to meet horizontal accuracy.

Vertical Positional Accuracy:

The topographic portion of this lidar dataset was tested to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 10 cm RMSEz Vertical Accuracy Class.

Actual NVA accuracy was found to be RMSEz =3.9 cm, equating to +/- 7.6 cm at 95% confidence level.

Actual VVA accuracy was found to be +/- 5.9 cm at the 95th percentile.

The bathymetric portion of this lidar dataset was tested to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for an 18.5 cm RMSEz Vertical Accuracy Class. Actual bathymetric vertical accuracy was found to be RMSEz = 8.4 cm, equating to +/- 16.5 cm at 95% confidence level.

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-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

Lineage Statement:

The NOAA Office for Coastal Management (OCM) downloaded this data from the USGS rockyweb site. OCM processed the data to make it available for custom download from the NOAA Digital Coast Data Access Viewer (DAV) and for bulk download from AWS S3.

Sources

USGS LAZ Download - MD_PotomacRiverTopoBathy_2019

CC ID: 1270306
Contact Role Type: Publisher
Contact Type: Organization
Contact Name: USGS
Citation URL: https://rockyweb.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/MD_PotomacRiverTopoBathy_2019_D19/MD_PotomacRiver_Bathy_2019/LAZ/
Citation URL Name: USGS LAZ download

Process Steps

Process Step 1

CC ID: 1270234
Description:

The boresight for each lift was done individually as the solution may change slightly from lift to lift. The initial points for each mission calibration were inspected for flight line errors, flight line overlap, slivers or gaps in the data, point data minimums, or issues with the lidar unit or GPS. Roll, pitch and scanner scale were optimized during the calibration process until the relative accuracy was met.

Dewberry utilized Bayesmap StripAlign for this alignment procedure. This alignment procedure corrected systematic issues globally, per aircraft lift, per flightline, and finally based on local errors along the flight trajectory. Error adjustments included internal sensor parameters. Due to the complex geometric relationship of the elliptical scan pattern the forward and reverse directions must be aligned independently. Additionally, since the green and NIR scanner map different surfaces, they were also aligned independently, then corrected to match each other.

Difference rasters (DZ orthos) were generated, adjustment parameters were reviewed, and registration/match regions were reviewed to ensure data quality.

A final vertical accuracy check of the boresighted flight lines was completed against the surveyed check points after the z correction to ensure the requirement of NVA = 19.6 cm 95% Confidence Level was met.

Point classification was performed according to USGS Lidar Base Specification 1.3. Bare earth DEMs were exported from the classified point cloud. Synthetic points generated by Leica refraciton correction algorithms are present in this dataset. Please see the final project report for more details on the synthetic points

Process Date/Time: 2020-03-01 00:00:00

Process Step 2

CC ID: 1270235
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 Riegl's automated refraction correction software based on the software's detection of water. Where the automated process missed discrete water bodies that did not contain valid bathymetry (submerged topography) data, breaklines were manually drawn and added to a separate feature class to ensure the correct classification of the point cloud.

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

Geometrically unused points at the edges of flight lines were flagged using the withheld bit. This includes synthetically generated class 42 (synthetic water surface) points at the edges of flight lines. All class 42 points were flagged using the synthetic bit.

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. GeoCue 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: 2020-03-01 00:00:00

Process Step 3

CC ID: 1270307
Description:

The NOAA Office for Coastal Management (OCM) downloaded 247 laz point data files from this USGS site:

https://rockyweb.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/MD_PotomacRiverTopoBathy_2019_D19/MD_PotomacRiver_Bathy_2019/LAZ/

The data were in UTM Zone 18N (NAD83 (2011), meters coordinates and NAVD88 (Geoid12B) elevations in meters. The data were classified as: 1 - Unclassified, 2 - Ground, 7 - Low Noise, 17 - Bridge Deck, 18 - High Noise, 40 - Bathymetry bottom, 41 - Water Surface, 42 - Synthetic Water Surface, 45 - No bathymetry bottom found. OCM processed all classifications of points to the Digital Coast Data Access Viewer (DAV). Classes available on the DAV are: 1, 2, 7, 17, 18, 40, 41 ,42, 45.

OCM performed the following processing on the data for Digital Coast storage and provisioning purposes:

1. Internal OCM scripts were run to check the number of points by classification and by flight ID and the gps, elevation, and intensity ranges.

2. Internal OCM scripts were run on the laz files to:

a. Convert from orthometric (NAVD88) elevations to NAD83 (2011) ellipsoid elevations using the Geoid12B model

b. Convert from UTM Zone 18N (NAD83 (2011), meters coordinates to geographic coordinates

c. Assign the geokeys, sort the data by gps time and zip the data to database and to AWS S3

Process Date/Time: 2023-09-01 00:00:00
Process Contact: Office for Coastal Management (OCM)

Related Items

Item Type Relationship Type Title
Data Set (DS) Cross Reference 2021 USGS Topobathy Lidar: Potomac River, MD

Catalog Details

Catalog Item ID: 70734
GUID: gov.noaa.nmfs.inport:70734
Metadata Record Created By: Rebecca Mataosky
Metadata Record Created: 2023-09-01 20:03+0000
Metadata Record Last Modified By: SysAdmin InPortAdmin
Metadata Record Last Modified: 2023-10-17 16:12+0000
Metadata Record Published: 2023-09-06
Owner Org: OCMP
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Last Review Date: 2023-09-06
Metadata Review Frequency: 1 Year
Metadata Next Review Date: 2024-09-06