Short Citation:
OCM Partners, 2021: 2016 - 2019 USGS Lidar: Alabama 25 County, https://www.fisheries.noaa.gov/inport/item/64305.

Item Identification

Title: 2016 - 2019 USGS Lidar: Alabama 25 County
Short Name: al2016_25county_m9174_metadata.xml
Status: Completed
Creation Date: 2016
Abstract:

This data set is tiled lidar point cloud LAS files v1.4, for the 2016 Alabama 25 County lidar area of interest (AOI).

USGS NGTOC task order G17PD00243 required Spring 2017 LiDAR surveys to be collected over 18,845 square miles covering part or all of 25 counties in Alabama. These counties are Autauga, Baldwin, Barbour, Bullock, Butler, Chambers, Cherokee, Clarke, Conecuh, Covington, Crenshaw, Elmore, Etowah, Henry, Houston, Lamar, Limestone, Macon, Monroe, Pike, Randolph, Russell, Shelby, Tallapoosa, and Winston. Aerial LiDAR data for this task order was planned, acquired, processed, and produced at an aggregate nominal pulse spacing (ANPS) of 0.7 meters and in compliance with USGS National Geospatial Program LiDAR Base Specification version 1.2.

The data are divided up in 8 blocks. Please see the kmz provided in the URL section of this metadata record for the block footprints.

Block 1 - Lamar, Limestone, Winston Counties

Block 2 - Cherokee, Etowah, Shelby Counties

Block 3 - Chambers, Randolph, Tallapoosa (partial) Counties

Block 4 - Autauga, Barbour (partial), Bullock (partial), Elmore, Macon, Russell Counties

Block 5 - Barbour (partial), Bullock (partial), Henry, Houston Counties

Block 6 - Barbour (partial), Bullock, (partial), Butler (partial), Conecuh (partial), Covington, Crenshaw, Pike Counties

Block 7 - Baldwin (partial), Butler (partial), Clarke, Conecuh (partial), Monroe Counties

Block 8 - Baldwin County (partial)

Isolated gaps in GPS data were identified in several missions covering this project. As both, the IMU data and pulse data, were present across these gaps, using the fixed positions of the GPS on either end, the aircraft velocity across the gaps, and the IMU data, LiDAR calibration staff were able to reach an effective solution to address the GPS voids. Because these gaps were not uniform in size or correction, this extended the iterative LiDAR calibration efforts on this project. Subsequent rigorous data checking confirmed adequate results to meet the required accuracy specs. The USGS QA Team already reviewed affected data (blocks) for this project and found no QA/QC discrepancies to report regarding those gaps.

Geographic Extent: This data set is consisting of lidar point cloud, classified lidar, digital elevation model, and lidar intensity images which all pieces encompasses the 2016 Alabama 25 County lidar (Pilot) area of interest (AOI), approximately 18,845 square miles or 48,408 square kilometers.

Data set Description: This data set consists of lidar point cloud LAS swath files and tiled LAS files. Each LAS file contains lidar point information, which has been calibrated, controlled, and classified. Each file represents a separate swath of lidar.

Ground Conditions: water at normal levels; no unusual inundation; no snow; leaf off

How the Withheld Points are Identified: Withheld (ignore) points were identified in the files using the standard LAS Withheld bit.

Class Code:1

Class Item:Unclassified

Class Code:2

Class Item:Ground

Class Code:7

Class Item:Low Noise

Class Code:9

Class Item:Water

Class Code:10

Class Item:Ignored Ground

Class Code:17

Class Item:Bridges

Class Code:18

Class Item:High Noise

The NOAA Office for Coastal Management (OCM) downloaded the laz files from these USGS sites and processed the data to the Data Access Viewer (DAV) and to https. The total number of files downloaded and processed was 23,054.

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_AL_25Co_B1_2017/ Number of files: 2305

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_AL_25Co_B2_2017/ Number of files: 2500

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_AL_25Co_B3_2017/ Number of files: 2243

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_AL_25Co_B4_2017/ Number of files: 3765

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_AL_25Co_B5_2017/ Number of files: 2505

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_AL_25Co_B6_2017/ Number of files: 3778

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_AL_25Co_B7_2017/ Number of files: 3879

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_AL_25Co_B8_2017/ Number of files: 2075

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/AL_25_County_Lidar_2017_B17/ Number of files: 4

The hydro breaklines were also downloaded from these USGS sites and are available for download at the link provided in the URL section of this metadata record. Please note that these products have not been reviewed by the NOAA Office for Coastal Management (OCM) and any conclusions drawn from the analysis of this information are not the responsibility of NOAA or OCM.

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/metadata/AL_25_County_Lidar_2017_B17/AL_25Co_B1_2017/breaklines/

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/metadata/AL_25_County_Lidar_2017_B17/AL_25Co_B2_2017/breaklines/

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/metadata/AL_25_County_Lidar_2017_B17/AL_25Co_B3_2017/breaklines/

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/metadata/AL_25_County_Lidar_2017_B17/AL_25Co_B4_2017/breaklines/

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/metadata/AL_25_County_Lidar_2017_B17/AL_25Co_B5_2017/breaklines/

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/metadata/AL_25_County_Lidar_2017_B17/AL_25Co_B6_2017/breaklines/

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/metadata/AL_25_County_Lidar_2017_B17/AL_25Co_B7_2017/breaklines/

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/metadata/AL_25_County_Lidar_2017_B17/AL_25Co_B8_2017/breaklines/

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/metadata/AL_25 20County 20Lidar_2017_B17/AL_25Co_TL_2017/breaklines/

Purpose:

The primary purpose of the lidar survey was to establish measurements of the bare earth surface, as well as top surface feature data for providing geometric inputs for modeling, other numerical modeling and economic related assessments.

Supplemental Information:

All lidar data was acquired, calibrated, and used in the creation of lidar derived products by Atlantic.

The following are the USGS lidar fields in JSON:

{

"ldrinfo" : {

"ldrspec" : "USGS-NGP Base Lidar Specification v1.2",

"ldrsens" : "Leica ALS70-HP",

"ldrmaxnr" : "unlimited",

"ldrnps" : "0.71 ",

"ldrdens" : "2.2 ",

"ldranps" : "0. ",

"ldradens" : "4.50 ",

"ldrfltht" : "2,000 ",

"ldrfltsp" : "130",

"ldrscana" : "45",

"ldrscanr" : "35.1",

"ldrpulsr" : "264,800",

"ldrpulsd" : "4",

"ldrpulsw" : "0.50",

"ldrwavel" : "1064",

"ldrmpia" : "1",

"ldrbmdiv" : "0.15",

"ldrswatw" : "1,663",

"ldrswato" : "20",

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

},

"ldraccur" : {

"ldrchacc" : "0.321",

"rawnva" : "-999999",

"rawnvan" : "-999999",

"clsnva" : "0.087",

"clsnvan" : "353",

"clsvva" : ".1154",

"clsvvan" : "287"

},

"lasinfo" : {

"lasver" : "1.4",

"lasprf" : "6",

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

"lasolap" : "Swath "overage" points were identified in these files using the standard LAS overlap bit.",

"lasintr" : "11",

"lasclass" : {

"clascode" : "1",

"clasitem" : "Unclassified"

},

"lasclass" : {

"clascode" : "2",

"clasitem" : "Ground"

},

"lasclass" : {

"clascode" : "7",

"clasitem" : "Low Noise"

},

"lasclass" : {

"clascode" : "9",

"clasitem" : "Water"

},

"lasclass" : {

"clascode" : "10",

"clasitem" : "Ignored Ground"

},

"lasclass" : {

"clascode" : "17",

"clasitem" : "Bridges"

},

"lasclass" : {

"clascode" : "18",

"clasitem" : "High Noise"

}

}}

Keywords

Theme Keywords

Thesaurus Keyword
UNCONTROLLED
Global Change Master Directory (GCMD) Science Keywords Earth Science > Land Surface > Topography > Terrain Elevation
ISO 19115 Topic Category elevation
None beach
None DEM
None DEM
None digital elevation model
None Elevation Data
None erosion
None Intensity Image
None laser
None lidar
None Lidar
None Topography

Spatial Keywords

Thesaurus Keyword
UNCONTROLLED
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 > Alabama
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Autauga County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Baldwin County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Barbour County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Bullock County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Butler County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Chambers County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Cherokee County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Clarke County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Conecuh County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Covington County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Crenshaw County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Elmore County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Etowah County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Henry County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Houston County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Lamar County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Limestone County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Macon County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Monroe County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Pike County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Randolph County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Russell County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Shelby County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Tallapoosa County
Global Change Master Directory (GCMD) Location Keywords Continent > North America > United States Of America > Alabama > Winston County
Global Change Master Directory (GCMD) Location Keywords Vertical Location > Land Surface
None U.S. Coastline

Instrument Keywords

Thesaurus Keyword
UNCONTROLLED
Global Change Master Directory (GCMD) Instrument Keywords Earth Remote Sensing Instruments > Active Remote Sensing > Profilers/Sounders > Lidar/Laser Sounders > LIDAR > Light Detection and Ranging

Platform Keywords

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

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: As Needed
Data Presentation Form: Model (digital)
Entity Attribute Detail Citation:

Lidar tiles and associated derived products for USGS

Distribution Liability:

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

Data Set Credit: Atlantic

Support Roles

Data Steward

CC ID: 1043666
Date Effective From: 2021
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: 1043665
Date Effective From: 2021
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: 1043667
Date Effective From: 2021
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: 1043668
Date Effective From: 2021
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 Description:

Overall data set, including all 8 blocks.

Extent Group 1 / Geographic Area 1

CC ID: 1043671
W° Bound: -88.29664
E° Bound: -84.82097
N° Bound: 34.999031
S° Bound: 30.20865

Extent Group 1 / Time Frame 1

CC ID: 1043670
Time Frame Type: Range
Start: 2016-12-02
End: 2019-11-12
Description:

Overall dates of collection for all blocks.

Extent Group 1 / Time Frame 2

CC ID: 1044105
Time Frame Type: Range
Start: 2016-12-02
End: 2017-02-15
Description:

Dates of collection for Block 1 - Lamar, Limestone, Winston Counties

Extent Group 1 / Time Frame 3

CC ID: 1044106
Time Frame Type: Range
Start: 2016-12-28
End: 2017-03-09
Description:

Dates of collection for Block 2 - Cherokee, Etowah, Shelby Counties

Extent Group 1 / Time Frame 4

CC ID: 1044107
Time Frame Type: Range
Start: 2017-02-26
End: 2017-11-20
Description:

Dates of collection for Block 3 - Chambers, Randolph, Tallapoosa (partial) Counties

Extent Group 1 / Time Frame 5

CC ID: 1044108
Time Frame Type: Range
Start: 2017-02-17
End: 2017-04-02
Description:

Dates of collection for Block 4 - Autauga, Barbour (partial), Bullock (partial), Elmore, Russell Counties

Extent Group 1 / Time Frame 6

CC ID: 1044109
Time Frame Type: Range
Start: 2017-03-16
End: 2017-04-02
Description:

Dates of collection for Block 5 - Barbour (partial), Bullock (partial), Henry, Houston Counties

Extent Group 1 / Time Frame 7

CC ID: 1044111
Time Frame Type: Range
Start: 2018-01-02
End: 2018-01-19
Description:

Dates of collection for Block 7 - Baldwin (partial), Butler (partial), Clarke, Conecuh (partial), Monroe Counties

Extent Group 1 / Time Frame 8

CC ID: 1044110
Time Frame Type: Range
Start: 2017-03-19
End: 2018-12-18
Description:

Dates of collection for Block 6 - Barbour (partial), Bullock (partial), Butler (partial), Conecuh (partial), Covington, Crenshaw, Pike Counties

Extent Group 1 / Time Frame 9

CC ID: 1044112
Time Frame Type: Range
Start: 2018-01-14
End: 2018-12-17
Description:

Dates of collection for Block 8 - Baldwin (partial)

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: 1043721

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: 1043673
Start Date: 2021-02-22
End Date: Present
Download URL: http://coast.noaa.gov/htdata/lidar2_z/geoid18/data/9174
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2021 - 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: LAZ

Distribution 2

CC ID: 1043672
Start Date: 2021-02-22
End Date: Present
Download URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=9174/details/9174
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2021 - 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: Zip
Compression: Zip

URLs

URL 1

CC ID: 1043662
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: 1043663
URL: https://coast.noaa.gov/htdata/lidar2_z/geoid18/data/9174/supplemental/al2017_25county_m9174.kmz
Name: Browse graphic
URL Type:
Browse Graphic
File Resource Format: KML
Description:

This graphic displays the footprint for this lidar data set.

URL 3

CC ID: 1043722
URL: https://coast.noaa.gov/htdata/lidar2_z/geoid18/data/9174/breaklines/
Name: Hydro breaklines
URL Type:
Online Resource
File Resource Format: zip
Description:

Link to the data set hydro breaklines.

URL 4

CC ID: 1043723
URL: https://coast.noaa.gov/htdata/lidar2_z/geoid18/data/9174/supplemental/
Name: Lidar Reports
URL Type:
Online Resource
File Resource Format: pdf
Description:

Link to the data set reports.

URL 5

CC ID: 1043725
URL: https://coast.noaa.gov/htdata/lidar2_z/geoid18/data/9174/supplemental/16113_AL_BAA_25_Counties_LiDAR_Blocks.kmz
Name: Block footprints
URL Type:
Browse Graphic
File Resource Format: kmz
Description:

This graphic displays the boundaries of each of the eight blocks that make up this data set.

Technical Environment

Description:

CloudPro 1.2.0 Build 85620; GeoCue Version 2014.1.21.2; Windows 7 Operating System

\\lidarsrv\GC_Warehouse_5\80658\30\*.las

184 GB

Data Quality

Vertical Positional Accuracy:

A total of 761 ground survey points were collected in support of this project, including 136 LiDAR Control Points (LCP), 340 Non-vegetated Vertical Accuracy (NVA) and 285 Vegetated Vertical Accuracy (VVA).

Point cloud data accuracy was tested against a Triangulated Irregular Network (TIN) constructed from LiDAR points in clear and open areas. A clear and open area can be characterized with respect to topographic and ground cover variation such that a minimum of five (5) times the Nominal Pulse Spacing (NPS) exists with less than 1/3 of the RMSEZ deviation from a low-slope plane. Slopes that exceed ten (10) percent were avoided.

The NVA value is a requirement that must be met, regardless of any allowed “busts” in the VVA(s) for individual land cover types within the project. Checkpoints for each assessment (NVA and VVA) are required to be well-distributed throughout the land cover type, for the entire project area.

Each land cover type representing ten (10) percent or more of the total project area were tested and reported with a VVA. In land cover categories other than dense urban areas, the tested points did not have obstructions forty-five (45) degrees above the horizon to ensure a satisfactory TIN surface. The VVA value is provided as a target. It is understood that in areas of dense vegetation, swamps, or extremely difficult terrain, this value may be exceeded.

Vertical Accuracy of the point cloud and bare-earth lidar data was assessed and reported in accordance with the ASPRS Positional Accuracy Standards for Digital Geospatial Data;

Required Non Vegetated Vertical Accuracy (NVA) : 0.196m

Required Vegetated Vertical Accuracy (VVA): 0.294 m.

This data set was tested to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data (2014) for a 10.0 (cm) RMSEz Vertical Accuracy Class. Actual NVA accuracy of the bare-earth was found to be RMSEz = 0.0817 m, equating to +/- 0.1601 m at 95% confidence level.

Actual VVA accuracy was found to be RMSEz = 0.1192 m, equating to +/- 0.2335 m at the 95th percentile.

Completeness Report:

The raw LAS data files included all data points collected. No points have been removed or excluded. A visual qualitative assessment was performed to ensure data completeness. The raw point cloud is of good quality and data passes Fundamental Vertical Accuracy specifications.Void areas (i.e., areas outside the project boundary but within the tiling scheme) are coded using a unique NODATA value. This value is identified in the appropriate location within the file header.

Conceptual Consistency:

All lidar data and lidar derived data covers the entire 18,845 square miles area of interest for the pilot area. All lidar point cloud tiles show no edge artifacts or mismatches from tile to tile. Void areas (i.e. areas outside the project boundary but within the tiling scheme) are coded using a unique NODATA value. This value is identified in the appropriate location within the file header. Data cover 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:

Atlantic collected lidar data for the USGS Alabama 25 County data set. This data was made available on the USGS rockyftp site. NOAA OCM downloaded the laz data to process to the Data Access Viewer to make available for free custom and bulk downloads.

Sources

Atlantic

CC ID: 1043737

USGS

CC ID: 1043738

Process Steps

Process Step 1

CC ID: 1043650
Description:

Ground Control Survey

A total of 761 ground survey points were collected in support of this project, including 136 LiDAR Control Points (LCP), 340 Non-vegetated Vertical Accuracy (NVA) and 285 Vegetated Vertical Accuracy (VVA).

Point cloud data accuracy was tested against a Triangulated Irregular Network (TIN) constructed from LiDAR points in clear and open areas. A clear and open area can be characterized with respect to topographic and ground cover variation such that a minimum of five (5) times the Nominal Pulse Spacing (NPS) exists with less than 1/3 of the RMSEZ deviation from a low-slope plane. Slopes that exceed ten (10) percent were avoided.

Each land cover type representing ten (10) percent or more of the total project area were tested and reported with a VVA. In land cover categories other than dense urban areas, the tested points did not have obstructions forty-five (45) degrees above the horizon to ensure a satisfactory TIN surface. The VVA value is provided as a target. It is understood that in areas of dense vegetation, swamps, or extremely difficult terrain, this value may be exceeded.

The NVA value is a requirement that must be met, regardless of any allowed “busts” in the VVA(s) for individual land cover types within the project. Checkpoints for each assessment (NVA and VVA) are required to be well-distributed throughout the land cover type, for the entire project area.

Process Date/Time: 2019-11-10 00:00:00

Process Step 2

CC ID: 1043651
Description:

Aerial Lidar Acquisition: Atlantic acquired 882 passes of the AOI as a series of perpendicular and/or adjacent flight-lines executed in 83 flight missions conducted between December 28, 2016 and November 10, 2019. Onboard differential Global Navigation Satellite System (GNSS) unit(s) recorded sample aircraft positions at 2 hertz (Hz) or more frequency. LiDAR data was only acquired when a minimum of six (6) satellites were in view.

Process Date/Time: 2019-11-10 00:00:00

Process Step 3

CC ID: 1043652
Description:

LiDAR Point Cloud Generation

Atlantic utilized Leica software products to download the IPAS ABGNSS/IMU data and raw laser scan files from the airborne system. Waypoint Inertial Explorer is used to extract the raw IPAS ABGNSS/IMU data, which is further processed in combination with controlled base stations to provide the final Smoothed Best Estimate Trajectory (SBET) for each mission. The SBETs are combined with the raw laser scan files to export the LiDAR ASCII Standard (*.las) formatted swath point clouds.

Process Date/Time: 2019-11-10 00:00:00

Process Step 4

CC ID: 1043653
Description:

Smooth Surface Repeatability (Interswath)

Departures from planarity of first returns within single swaths in non-vegetated areas were assessed at multiple locations with hard surface areas (parking lots or large rooftops) inside the project area. Each area was evaluated using signed difference rasters (maximum elevation – minimum elevation) at a cell size equal to 2 x ANPS, rounded to the next integer. The following figure depicts a sample of the assessment.

Process Date/Time: 2019-11-10 00:00:00

Process Step 5

CC ID: 1043654
Description:

LiDAR Calibration

Using a combination of GeoCue, TerraScan and TerraMatch; overlapping swath point clouds are corrected for any orientation or linear deviations to obtain the best fit swath-to-swath calibration. Relative calibration was evaluated using advanced plane-matching analysis and parameter corrections derived. This process was repeated interactively until residual errors between overlapping swaths, across all project missions, was reduced to ≤2cm. A final analysis of the calibrated LiDAR is preformed using a TerraMatch tie line report for an overall statistical model of the project area. Individual control point assessments for this project can be found in Section VI of this report.

Upon completion of the data calibration, a complete set of elevation difference intensity rasters (dZ Orthos) are produced. A user-defined color ramp is applied depicting the offsets between overlapping swaths based on project specifications. The dZ orthos provide an opportunity to review the data calibration in a qualitative manner. Atlantic assigns green to all offset values that fall below the required RMSDz requirement of the project. A yellow color is assigned for offsets that fall between the RMSDz value and 1.5x of that value. Finally, red values are assigned to all values that fall beyond 1.5x of the RMSDz requirements of the project.

Process Date/Time: 2019-11-10 00:00:00

Process Step 6

CC ID: 1043655
Description:

Lidar Classification: The calibrated Lidar data was run through automated classification routines and then manually checked and edited. The data was classified into the following classes: 1-unclassified*, 2-ground, 7-low noise, 9-water, 10-ignored ground, 17-bridges, and 18-high noise

Process Date/Time: 2019-11-10 00:00:00

Process Step 7

CC ID: 1043656
Description:

Lidar Intensity Imagery Creation: All lidar intensity imagery was created from the final calibrated and classified lidar point cloud. Intensity images were produced from all classified points and are posted to a 1 meter cell size. Intensity images were cut to match the tile index and have corresponding names to match tile names.

Process Date/Time: 2019-11-10 00:00:00

Process Step 8

CC ID: 1043657
Description:

The NOAA Office for Coastal Management (OCM) downloaded the laz files from these USGS sites and processed the data to the Data Access Viewer (DAV) and to https. The total number of files downloaded and processed was 23,054.

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_AL_25Co_B1_2017/ Number of files: 2305

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_AL_25Co_B2_2017/ Number of files: 2500

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_AL_25Co_B3_2017/ Number of files: 2243

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_AL_25Co_B4_2017/ Number of files: 3765

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_AL_25Co_B5_2017/ Number of files: 2505

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_AL_25Co_B6_2017/ Number of files: 3778

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_AL_25Co_B7_2017/ Number of files: 3879

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/USGS_LPC_AL_25Co_B8_2017/ Number of files: 2075

ftp://rockyftp.cr.usgs.gov/vdelivery/Datasets/Staged/Elevation/LPC/Projects/AL_25_County_Lidar_2017_B17/ Number of files: 4

The data were in UTM Zone 16 (NAD83 2011), meters, coordinates and NAVD88 (Geoid12B) elevations in meters. The data were classified as: 1 - Unclassified, 2 - Ground, 7 - Low Noise, 9 - Water, 10 - Ignored Ground, 17 - Bridge Decks, 18 - High Noise. OCM processed all classifications of points to the Digital Coast Data Access Viewer (DAV). Classes available on the DAV are: 1, 2, 7, 9, 10, 17, 18.

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

1. An internal OCM script was run to check the number of points by classification and by flight ID and the gps and intensity ranges. This script found a file (USGS_LPC_AL_25Co_B2_2017_16S_FC_2160.laz) in Block 2 that had a bad point. The point had a bad longitude value. The point was deleted from the file before processing.

2. Internal OCM scripts were run on the laz files to convert from orthometric (NAVD88) elevations to ellipsoid elevations using the Geoid12B model, to convert from UTM Zone 16 (NAD83 2011) coordinates in meters to geographic coordinates, to assign the geokeys, to sort the data by gps time and zip the data to database and to http.

Process Date/Time: 2021-02-22 00:00:00
Process Contact: Office for Coastal Management (OCM)

Catalog Details

Catalog Item ID: 64305
Metadata Record Created By: Rebecca Mataosky
Metadata Record Created: 2021-02-22 19:04+0000
Metadata Record Last Modified By: Rebecca Mataosky
Metadata Record Last Modified: 2021-03-03 16:19+0000
Metadata Record Published: 2021-02-26
Owner Org: OCMP
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Next Review Date: 2022-02-27