Search Help Show/Hide Menu
Summary
Item Identification
Keywords
Physical Location
Data Set Info
Support Roles
Extents
Spatial Info
Access Info
Distribution Info
URLs
Data Quality
Data Management
Lineage
Related Items
Catalog Details

Summary

Browse Graphic

Short Citation
OCM Partners, 2024: 2018 AK DGGS Lidar: Sitka, Alaska, https://www.fisheries.noaa.gov/inport/item/67930.
Full Citation Examples

Abstract

The State of Alaska Division of Geological & Geophysical Surveys (DGGS) produced airborne lidar-derived elevation data for Sitka, Alaska. Airborne and ground surveys occurred between the 27th and 30th of April, 2018. These data were produced to assess bare earth slope conditions as part of an overarching, multi-hazard risk analysis for the study area, coordinated through the Federal Emergency Management Agency (FEMA) Cooperating Technical Partners (CTP) program. The project was initiated in response to a tragic debris flow incident that took three Alaskans' lives in 2015. This data collection is released as a Raw Data File with an open end-user license. All files can be downloaded free of charge from the Alaska Division of Geological & Geophysical Surveys website (http://doi.org/10.14509/30531).

The NOAA Office for Coastal Management (OCM) downloaded this data set from this AK DGGS site:

https://elevation.alaska.gov/

These files were processed to make the data available for custom and bulk download from the NOAA Digital Coast Data Access Viewer (DAV) . The total number of files downloaded and processed was 263. During processing, OCM noted that there are points that fall on water bodies and buildings that are classified as ground.

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

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.

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, geoscientificInformation, 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

-135.430199° W, -135.180975° E, 57.166765° N, 57.024363° S

Time Frame 1
2018-04-27 - 2018-04-30

Item Identification

Title: 2018 AK DGGS Lidar: Sitka, Alaska
Short Name: ak2018_sitka_m9611_metadata
Status: Completed
Creation Date: 2018
Publication Date: 2020
Abstract:

The State of Alaska Division of Geological & Geophysical Surveys (DGGS) produced airborne lidar-derived elevation data for Sitka, Alaska. Airborne and ground surveys occurred between the 27th and 30th of April, 2018. These data were produced to assess bare earth slope conditions as part of an overarching, multi-hazard risk analysis for the study area, coordinated through the Federal Emergency Management Agency (FEMA) Cooperating Technical Partners (CTP) program. The project was initiated in response to a tragic debris flow incident that took three Alaskans' lives in 2015. This data collection is released as a Raw Data File with an open end-user license. All files can be downloaded free of charge from the Alaska Division of Geological & Geophysical Surveys website (http://doi.org/10.14509/30531).

The NOAA Office for Coastal Management (OCM) downloaded this data set from this AK DGGS site:

https://elevation.alaska.gov/

These files were processed to make the data available for custom and bulk download from the NOAA Digital Coast Data Access Viewer (DAV) . The total number of files downloaded and processed was 263. During processing, OCM noted that there are points that fall on water bodies and buildings that are classified as ground.

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

Purpose:

These data were produced to assess bare earth slope conditions as part of an overarching, multi-hazard risk analysis for the study area, coordinated through the Federal Emergency Management Agency (FEMA) Cooperating Technical Partners (CTP) program. The project was initiated in response to a tragic debris flow incident that took three Alaskans' lives in 2015. This data release is one of a series of DGGS publications to present elevation data.

Supplemental Information:

>canopy height model: The CHM displays vegetation heights as the difference between DSM and DTM heights. The CHM is a single-band, 32-bit float GeoTIFF file with a ground sample distance of 0.5 meters. No Data value is set to -3.40282306074e+038. Note: there are some negative values in the CHM, present in low confidence areas of the DSM and DTM.

>classified point cloud data: Classified point cloud data is provided in this collection in compressed .laz format. An average point spacing of 0.15 meters was calculated from all returns and all non-noise classes.

>digital surface model: The DSM represents human-observable surface elevations, which include vegetation, buildings, etc. The DSM is a single band, 32-bit GeoTIFF file with a ground sample distance of 0.5 meters. No Data value is set to -3.40282306074e+038.

>digital terrain model: The DTM represents elevations of the ground surface by penetrating or flattening any vegetation, bridges, buildings, etc. The DTM is a single-band, 32-bit float GeoTIFF file with a ground sample distance of 0.5 meters. No Data value is set to -3.40282306074e+038.

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
ISO 19115 Topic Category
geoscientificInformation

Spatial Keywords

Thesaurus Keyword
Global Change Master Directory (GCMD) Location Keywords
CONTINENT
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 > ALASKA
Global Change Master Directory (GCMD) Location Keywords
VERTICAL LOCATION > LAND SURFACE
UNCONTROLLED
None Sitka

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:

The State of Alaska makes no expressed or implied warranties (including warranties for merchantability and fitness) with respect to the character, functions, or capabilities of the electronic data or products or their appropriateness for any user's purposes. In no event will the State of Alaska be liable for any incidental, indirect, special, consequential, or other damages suffered by the user or any other person or entity whether from the use of the electronic services or products or any failure thereof or otherwise. In no event will the State of Alaska's liability to the Requestor or anyone else exceed the fee paid for the electronic service or product.

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: Funding was provided by the State of Alaska and by National Park Service award #P17AC00903 and award #P15AC01879., Daanen, R.P. Wolken, G.J. Herbst, A.M.

Support Roles

Data Steward

CC ID: 1184908
Date Effective From: 2022
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address: coastal.info@noaa.gov
Phone: (843) 740-1202
URL: https://coast.noaa.gov

Distributor

CC ID: 1184907
Date Effective From: 2022
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address: coastal.info@noaa.gov
Phone: (843) 740-1202
URL: https://coast.noaa.gov

Metadata Contact

CC ID: 1184909
Date Effective From: 2022
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address: coastal.info@noaa.gov
Phone: (843) 740-1202
URL: https://coast.noaa.gov

Point of Contact

CC ID: 1184910
Date Effective From: 2022
Date Effective To:
Contact (Organization): NOAA Office for Coastal Management (NOAA/OCM)
Address: 2234 South Hobson Ave
Charleston, SC 29405-2413
Email Address: coastal.info@noaa.gov
Phone: (843) 740-1202
URL: https://coast.noaa.gov

Extents

Currentness Reference: Ground Condition

Extent Group 1

Extent Group 1 / Geographic Area 1

CC ID: 1184913
W° Bound: -135.430199
E° Bound: -135.180975
N° Bound: 57.166765
S° Bound: 57.024363

Extent Group 1 / Time Frame 1

CC ID: 1184912
Time Frame Type: Range
Start: 2018-04-27
End: 2018-04-30

Spatial Information

Spatial Representation

Representations Used

Vector: Yes

Reference Systems

Reference System 1

CC ID: 1184927

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: 1184914
Start Date: 2022-09-26
End Date: Present
Download URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=9611/details/9611
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2022 - Present)
File Name: Customized Download
Description:

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

File Type (Deprecated): Zip
Compression: Zip

Distribution 2

CC ID: 1184915
Start Date: 2022-09-26
End Date: Present
Download URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/9611/index.html
Distributor: NOAA Office for Coastal Management (NOAA/OCM) (2022 - Present)
File Name: Bulk Download
Description:

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

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

URLs

URL 1

CC ID: 1184906
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: 1184928
URL: https://dggs.alaska.gov/webpubs/dggs/rdf/text/rdf2020_013.pdf
Name: Lidar Report
URL Type:
Online Resource
File Resource Format: pdf
Description:

Link to the lidar report.

URL 3

CC ID: 1184929
URL: https://coast.noaa.gov/lidar/viewer/v/noaapotree.html?m=9611&g=geoid12b
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.

URL 4

CC ID: 1184930
URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/entwine/geoid12b/9611/ept.json
Name: Entwine Point Tiles (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 5

CC ID: 1184931
URL: https://noaa-nos-coastal-lidar-pds.s3.amazonaws.com/laz/geoid12b/9611/supplemental/ak2018_sitka_m9611.kmz
Name: Browse Graphic
URL Type:
Browse Graphic
File Resource Format: kmz
Description:

This graphic displays the footprint for this lidar data set.

URL 6

CC ID: 1184932
URL: https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=9612/details/9612
Name: Custom DEM Download
URL Type:
Online Resource
File Resource Format: Zip
Description:

Link to custom download, from the Data Access Viewer (DAV), the raster Digital Elevation Model (DEM) data that were created from this lidar data set.

Data Quality

Horizontal Positional Accuracy:

Horizontal accuracy was not measured for this collection.

Vertical Positional Accuracy:

One hundred ground control points were used to determine a -0.015 m average offset from the point cloud, which was corrected with a uniform z-transformation of the lidar data. Point cloud accuracy was measured using 95 checkpoints to determine a root-mean-square error of 0.063 m for the project. The accompanying report provides a table of ground control measurements and summary statistics.

Completeness Report:

This data release is complete. Weather was partially cloudy throughout the survey, at times obscuring higher altitude topography in the study area. These conditions limited data coverage to areas below 980 meters elevation.

Conceptual Consistency:

Relative accuracy for this dataset has been evaluated as the interswath consistency, measured by comparing tie line points within swath overlap areas. The interswath root-mean-square error was calculated to be 0.008 m.

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 data were collected for the Alaska Division of Geological and Geophysical Surveys (DGGS) and made available on the AK DGGS Elevation Portal (https://elevation.alaska.gov/). The NOAA Office for Coastal Management (OCM) downloaded the data from this site to make the data available for custom downloads from the NOAA Digital Coast Data Access Viewer and for bulk downloads from the AWS S3 bucket.

Sources

Alaska Division of Geological and Geophysical Surveys (AK DGGS)

CC ID: 1184933
Contact Role Type: Originator
Contact Type: Organization
Contact Name: AK DGGS
Citation URL: https://elevation.alaska.gov/
Citation URL Name: AK DGGS Elevation Portal

Process Steps

Process Step 1

CC ID: 1184900
Description:

Airborne survey - The lidar survey was conducted with a Riegl VUX1-LR lidar scanner with an integrated GNSS and Northrop Grumman IMU system. The integration was designed by Phoenix LiDAR systems. This survey was flown with a pulse rate between 200,000-400,000 pulses/second and at a scan rate between 80 and 150 revolutions/second. This survey was flown with an average elevation of 400 m above ground level and a ground speed of approximately 40 m/s with a fixed-wing Cessna 185 aircraft. The scan angle was set from 55 to 305 degrees, centered normal to the aircraft's bottom. The accompanying report provides additional detail regarding flight conditions.

Process Date/Time: 2018-04-30 00:00:00

Process Step 2

CC ID: 1184901
Description:

Ground survey - Trimble R8 and R9 RTK GPS systems were used to collect 195 survey points, 100 of which were used as control points and 95 of which were used as checkpoints. Points were gathered by vehicle along the road system and by boat along the coastline. Points were adjusted for accuracy according to OPUS corrections in Trimble Business Center.

Process Date/Time: 2018-04-30 00:00:00

Process Step 3

CC ID: 1184902
Description:

Lidar dataset processing - SDCImport software was used to apply range thresholding, reflectance thresholding, and missed-time-around (MTA) disambiguation for preliminary point cloud noise filtering. In-flight IMU and GNSS data were coupled using Inertial Explorer software to produce the trajectory data. Spatial Explorer software was used to couple the trajectory data with the point cloud. The point cloud data were calibrated using tielines for roll, pitch, and yaw of the aircraft during the survey. This process was first run using all points, then on a per-flightline basis for additional accuracy. Interswath fluctuations in ground points were identified using overlapping tielines to further calibrate the data. The point cloud was classified in accordance with American Society for Photogrammetry and Remote Sensing (ASPRS) guidelines using project-tailored macros. Misclassified points were manually reclassified in post-processing QA/QC. The point cloud was converted from ellipsoidal to orthometric heights using geoid 12B, then uniformly adjusted to maintain a mean offset of 0 with collected ground control. Calibration, classification, and height adjustments were all executed in TerraSolid. Derived products were processed in ArcMap. DTM and DSM were produced using point triangulation with nearest-neighbor interpolation. The DTM was derived from all returns for ground classified points, while the DSM used first returns for all non-noise classes. The CHM was created by subtracting DTM height values from DSM height values. A lidar intensity image was created from first returns of all classes using mean binning.

Process Date/Time: 2019-01-01 00:00:00

Process Step 4

CC ID: 1184934
Description:

The NOAA Office for Coastal Management (OCM) downloaded 263 laz files from the Alaska Division of Geological and Geophysical Surveys Elevation Portal (https://elevation.alaska.gov/). The files contained classified elevation and intensity measurements for the 2018 Sitka Alaska project. The data were in UTM Zone 8 NAD83 (2011), meters coordinates and NAVD88 (GEOID12B) elevations in meters. During processing, OCM noted that there are points that fall on water bodies and buildings that are classified as ground. The data had the following classifications: 1 - Unclassified, 2 - Ground, 3- Low Vegetation, 4 - Medium Vegetation, 5 - High Vegetation, 6 - Building, 7 - Noise. OCM processed all points to the Digital Coast Data Access Viewer (DAV).

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 and intensity ranges.

2. Internal OCM scripts were run on the laz files to convert from UTM Zone 8 NAD83 (2011), meters coordinates to geographic coordinates, to convert from NAVD88 elevations to ellipsoid elevations using the GEOID12B model, to assign the geokeys, to sort the data by gps time, zip the data to database, and to create Cloud Optimized Point Cloud (COPC) version laz files that are available from the AWS S3 bucket.

Process Date/Time: 2022-10-19 00:00:00
Process Contact: Office for Coastal Management (OCM)

Related Items

Item Type Relationship Type Title
Data Set (DS) Cross Reference 2018 AK DGGS Lidar DEM: Sitka, Alaska

Catalog Details

Catalog Item ID: 67930
GUID: gov.noaa.nmfs.inport:67930
Metadata Record Created By: Rebecca Mataosky
Metadata Record Created: 2022-09-26 19:57+0000
Metadata Record Last Modified By: SysAdmin InPortAdmin
Metadata Record Last Modified: 2023-10-17 16:12+0000
Metadata Record Published: 2022-10-19
Owner Org: OCMP
Metadata Publication Status: Published Externally
Do Not Publish?: N
Metadata Last Review Date: 2022-10-19
Metadata Review Frequency: 1 Year
Metadata Next Review Date: 2023-10-19