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Item Identification
Keywords
Physical Location
Data Set Info
Support Roles
Extents
Spatial Info
Access Info
Distribution Info
URLs
Data Quality
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Catalog Details

Summary

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Short Citation
OCM Partners, 2024: 2016 DOWL Lidar DEM: Chena River Lakes, Alaska, https://www.fisheries.noaa.gov/inport/item/52874.
Full Citation Examples

Abstract

This metadata record was created by the NOAA Office for Coastal Management (OCM) because no metadata record was available for the data. Information to create this record was taken from the Quantum Spatial Chena River Lakes LiDAR Technical Data Report. There is a link to this report in the URL section of this metadata record. The report indicates that the data are in Alaska State Plane Zone 3, NAD83 (NSRS2007), US survey feet and in NAVD88 (GEOID06) with vertical units in US survey feet.

The NOAA Office for Coastal Management (OCM) downloaded the gridded Digital Elevation Model (DEM) data from the AK DGGS site (https://elevation.alaska.gov/) and processed the data to be available on the Digital Coast Data Access Viewer (DAV).

In addition to these bare earth Digital Elevation Model (DEM) data, the lidar point data that these DEM data were created from, are also available. These data are available for custom download at the link provided in the URL section of this metadata record.

In early 2016, Quantum Spatial (QSI) was contracted by DOWL, Inc. to collect Light Detection and Ranging (LiDAR) data in the spring of 2016 for the Chena River Lakes site in Alaska.

Distribution Information

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

  • GeoTIFF

    Bulk download of data files in the original coordinate system.

Access Constraints:

None

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be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions.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.

Controlled Theme Keywords

COASTAL ELEVATION, elevation, TERRAIN ELEVATION

Child Items

No Child Items for this record.

Contact Information

Point of Contact
NOAA Office for Coastal Management (NOAA/OCM)
coastal.info@noaa.gov
(843) 740-1202

Metadata Contact
NOAA Office for Coastal Management (NOAA/OCM)
coastal.info@noaa.gov
(843) 740-1202

Extents

Geographic Area 1

-147.321° W, -147.04° E, 64.838° N, 64.7° S

Time Frame 1
2016-05-01

Item Identification

Title: 2016 DOWL Lidar DEM: Chena River Lakes, Alaska
Short Name: ak2016_chena_dem_m8541_metadata
Status: Completed
Creation Date: 2017
Abstract:

This metadata record was created by the NOAA Office for Coastal Management (OCM) because no metadata record was available for the data. Information to create this record was taken from the Quantum Spatial Chena River Lakes LiDAR Technical Data Report. There is a link to this report in the URL section of this metadata record. The report indicates that the data are in Alaska State Plane Zone 3, NAD83 (NSRS2007), US survey feet and in NAVD88 (GEOID06) with vertical units in US survey feet.

The NOAA Office for Coastal Management (OCM) downloaded the gridded Digital Elevation Model (DEM) data from the AK DGGS site (https://elevation.alaska.gov/) and processed the data to be available on the Digital Coast Data Access Viewer (DAV).

In addition to these bare earth Digital Elevation Model (DEM) data, the lidar point data that these DEM data were created from, are also available. These data are available for custom download at the link provided in the URL section of this metadata record.

In early 2016, Quantum Spatial (QSI) was contracted by DOWL, Inc. to collect Light Detection and Ranging (LiDAR) data in the spring of 2016 for the Chena River Lakes site in Alaska.

Purpose:

Data were collected to aid DOWL, Inc. in assessing the topographic and geophysical properties of the study area and to support engineering and mapping endeavors.

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
UNCONTROLLED
None DEM
None erosion

Temporal Keywords

Thesaurus Keyword
UNCONTROLLED
None 2016
None May

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

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
Global Change Master Directory (GCMD) Platform Keywords
DEM > Digital Elevation Model

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: Unknown
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: DOWL, Inc.

Support Roles

Data Steward

CC ID: 757835
Date Effective From: 2018
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: 757836
Date Effective From: 2018
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: 757837
Date Effective From: 2018
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: 757838
Date Effective From: 2018
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: 1291083
W° Bound: -147.321
E° Bound: -147.04
N° Bound: 64.838
S° Bound: 64.7

Extent Group 1 / Time Frame 1

CC ID: 1291082
Time Frame Type: Discrete
Start: 2016-05-01

Spatial Information

Reference Systems

Reference System 1

CC ID: 1291080

Coordinate Reference System

CRS Type: Vertical
EPSG Code: EPSG:6360
EPSG Name: NAVD88 height (ftUS)
See Full Coordinate Reference System Information

Access Information

Security Class: Unclassified
Data Access Procedure:

Data is available online for custom and bulk 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: 757839
Start Date: 2018
End Date: Present
Download URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=8541
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2018 - Present)
File Name: Customized Download
Description:

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

File Type (Deprecated): Zip
Compression: Zip

Distribution 2

CC ID: 757840
Start Date: 2018
End Date: Present
Download URL: https://noaa-nos-coastal-lidar-pds.s3.us-east-1.amazonaws.com/dem/AK_Chena_DEM_2016_8541/index.html
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2018 - Present)
File Name: Bulk Download
Description:

Bulk download of data files in the original coordinate system.

File Type (Deprecated): GeoTIFF
Distribution Format: GeoTIFF

URLs

URL 1

CC ID: 757841
URL: https://coast.noaa.gov/
Name: NOAA's Office for Coastal Management (OCM) website
URL Type:
Online Resource
File Resource Format: HTML
Description:

Information on the NOAA Office for Coastal Management (OCM)

URL 2

CC ID: 757842
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: 757843
URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/8540/supplemental/ak2016_chena_m8540.kmz
Name: Browse graphic
URL Type:
Browse Graphic
File Resource Format: KML
Description:

This graphic displays the footprint for this lidar data set.

URL 4

CC ID: 757844
URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/8540/supplemental/ak2016_chena_m8540_lidar_report.pdf
Name: Dataset report
URL Type:
Online Resource
File Resource Format: PDF
Description:

Link to data set report.

URL 5

CC ID: 757845
URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=8540
URL Type:
Other
Description:

Link to custom download the lidar point data from which these raster Digital Elevation Model (DEM) data were created.

Data Quality

Vertical Positional Accuracy:

Absolute accuracy was assessed using Fundamental Vertical Accuracy (FVA) reporting designed to meet guidelines presented in the FGDC National Standard for Spatial Data Accuracy 2. FVA compares known ground quality assurance point data collected on open, bare earth surfaces with level slope (<20 degrees) to the triangulated surface generated by the LiDAR points. FVA is a measure of the accuracy of LiDAR point data in open areas where the LiDAR system has a high probability of measuring the ground surface and is evaluated at the 95% confidence interval (1.96 * RMSE). The mean and standard deviation of divergence of the ground surface model from quality assurance point coordinates are also considered during accuracy assessment. These statistics assume the error for x, y, and z is normally distributed, and therefore the skew and kurtosis of distributions are also considered when evaluating error statistics. For the Chena River Lakes survey, 80 quality assurance points were used for Fundamental Vertical Accuracy (FVA) calculations which resulted in an FVA value of 0.188 feet (0.057 meters) .

Vertical accuracy was also assessed using Supplemental Vertical Accuracy (SVA) and Consolidated Vertical Accuracy (CVA) reporting. SVA compares known ground check point data within individual land cover class categories to the triangulated ground surface generated by the ground classified LiDAR points while CVA compares known ground check points within all land cover classes. SVA and CVA are evaluated at the 95th percentile.

SVA

Brush - 0.452 ft (0.138 m)

Gravel - 0.152 ft (0.046 m)

Forest - 0.337 ft (0.102 m)

CVA - 0.231 ft (0.070 m)

Completeness Report:

Complete

Lineage

Process Steps

Process Step 1

CC ID: 1291075
Description:

Planning

In preparation for data collection, QSI reviewed the project area and developed a specialized flight plan to ensure complete coverage of the Chena River Lakes LiDAR study area at the target point density of ≥12.0 points/m2 (1.11 points/ft2). Acquisition parameters including orientation relative to terrain, flight altitude, pulse rate, scan angle, and ground speed were adapted to optimize flight paths and flight times while meeting all contract specifications.

Factors such as satellite constellation availability and weather windows must be considered during the planning stage. Any weather hazards or conditions affecting the flights were continuously monitored due to their potential impact on the daily success of airborne and ground operations. In addition, logistical considerations including private property access and potential air space restrictions were reviewed.

Process Step 2

CC ID: 1291076
Description:

Acquisition

The LiDAR survey was accomplished using a Leica ALS80 system mounted in a Cessna Caravan. Table 3 in the technical report summarizes the settings used to yield an average pulse density of greater than or equal to 12 pulses/m2 over the Chena River Lakes project area. The Leica ALS80 laser system can record unlimited range measurements (returns) per pulse. It is not uncommon for some types of surfaces (e.g., dense vegetation or water) to return fewer pulses to the LiDAR sensor than the laser originally emitted. The discrepancy between first return and overall delivered density will vary depending on terrain, land cover, and the prevalence of water bodies. All discernible laser returns were processed for the output dataset.

All areas were surveyed with an opposing flight line side-lap of ≥60% (≥100% overlap) in order to reduce laser shadowing and increase surface laser painting. To accurately solve for laser point position (geographic coordinates x, y and z), the positional coordinates of the airborne sensor and the attitude of the aircraft were recorded continuously throughout the LiDAR data collection mission. Position of the aircraft was measured twice per second (2 Hz) by an onboard differential GPS unit, and aircraft attitude was measured 200 times per second (200 Hz) as pitch, roll and yaw (heading) from an onboard inertial measurement unit (IMU). To allow for post-processing correction and calibration, aircraft and sensor position and attitude data are indexed by GPS time.

Process Date/Time: 2016-05-01 00:00:00

Process Step 3

CC ID: 1291077
Description:

Ground Control

Ground control surveys, including monumentation and the collection of ground survey points (GSPs), were conducted by DOWL to support the airborne acquisition. Ground control data were used to geospatially correct the aircraft positional coordinate data and to perform quality assurance checks on final LiDAR data.

QSI used static GNSS data provided by DOWL from base stations set up over three monument locations for the Chena River Lakes LiDAR project All survey data were reviewed by QSI staff upon receipt, and monument positions were verified by processing static GNSS data against nearby Continuously Operating Reference Stations (CORS) using the Online Positioning User Service (OPUS1).

Ground survey points were collected by DOWL using real time kinematic survey techniques and supplied to QSI for LiDAR calibration.

In addition to ground survey points, land cover class control points were collected and provided by DOWL throughout the study area. Individual accuracies were calculated for each land cover type to assess confidence in the LiDAR-derived ground models across land cover classes.

Process Step 4

CC ID: 1291078
Description:

Lidar Processing

Upon completion of data acquisition, QSI processing staff initiated a suite of automated and manual techniques to process the data into the requested deliverables. Processing tasks included GPS control computations, smoothed best estimate trajectory (SBET) calculations, kinematic corrections, calculation of laser point position, sensor and data calibration for optimal relative and absolute accuracy, and LiDAR point classification. Processing methodologies were tailored for the landscape.

Resolve kinematic corrections for aircraft position data using kinematic aircraft GPS and static ground GPS data. Develop a smoothed best estimate of trajectory (SBET) file that blends post-processed aircraft position with sensor head position and attitude recorded throughout the survey.

Calculate laser point position by associating SBET position to each laser point return time, scan angle, intensity, etc. Create raw laser point cloud data for the entire survey in *.las (ASPRS v. 1.2) format. Convert data to orthometric elevations by applying a geoid06 correction

Import raw laser points into manageable blocks to perform manual relative accuracy calibration and filter erroneous points. Classify ground points for individual flight lines.

Using ground classified points per each flight line, test the relative accuracy. Perform automated line-to-line calibrations for system attitude parameters (pitch, roll, heading), mirror flex (scale) and GPS/IMU drift. Calculate calibrations on ground classified points from paired flight lines and apply results to all points in a flight line. Use every flight line for relative accuracy calibration.

Classify resulting data to ground and other client designated ASPRS classifications. Assess statistical absolute accuracy via direct comparisons of ground classified points to ground control survey data.

Generate bare earth models as triangulated surfaces. Generate highest hit models as a surface expression of all classified points. Export all surface models as ESRI GRIDs at a 3.0 foot pixel resolution.

Correct intensity values for variability and export intensity images as GeoTIFFs at a 1.5 foot pixel resolution.

Process Step 5

CC ID: 1291079
Description:

The NOAA Office for Coastal Management (OCM) downloaded 507 DEM files from the Alaska Division of Geological and Geophysical Surveys data Portal (https://elevation.alaska.gov/). The report indicates that the data are in Alaska State Plane Zone 3, NAD83 (NSRS2007), US survey feet and in NAVD88 (GEOID06) with vertical units in US survey feet. The bare earth raster files are at a 3 ft grid spacing.

OCM converted the files to Cloud Optimized GeoTiffs and set the vertical georeferencing using GeoTiff 1.1 format.

Process Date/Time: 2023-06-26 00:00:00
Process Contact: Office for Coastal Management (OCM)

Catalog Details

Catalog Item ID: 52874
GUID: gov.noaa.nmfs.inport:52874
Metadata Record Created By: Rebecca Mataosky
Metadata Record Created: 2018-06-12 11:26+0000
Metadata Record Last Modified By: Kirk Waters
Metadata Record Last Modified: 2024-01-10 19:02+0000
Metadata Record Published: 2024-01-10
Owner Org: OCMP
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Last Review Date: 2022-03-16
Metadata Review Frequency: 1 Year
Metadata Next Review Date: 2023-03-16