67836 ak2020_barry_dem_m9579_metadata Data Set Published / External 49404 DEMs - partner (no harvest) Project Completed 2020 2021 The Alaska Division of Geological & Geophysical Surveys (DGGS) used aerial lidar to produce a classified point cloud, digital terrain model (DTM), surface model (DSM), and intensity model of land areas in northern Barry Arm, northwest Prince William Sound, Alaska, during near snow-free ground conditions on June 26, 2020. The goal of the survey is to provide high quality, modern topographic data in the recently deglacierized part of Barry Arm where significant landslide hazards exist. Aerial lidar and ground control data were collected on June 26, 2020, and subsequently processed in Terrasolid and ArcGIS. Ground control was collected on June 26, 2020, as well. All files can be downloaded free of charge from the Alaska Division of Geological & Geophysical Surveys website (http://doi.org/10.14509/30589). 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 1. NOAA OCM noted that there are artifact areas along some of the borders of the data set. The goal of the survey is to provide high quality, modern topographic data in the recently deglacierized part of Barry Arm where significant landslide hazards exist. This data release is one of a series of DGGS publications to present elevation data. >classified point cloud data: Classified point cloud data is provided in this collection in compressed LAZ format. Data are classified in accordance with ASPRS 2014 guidelines and contain return and intensity information. The average pulse spacing was 7.2 cm and the average density was 12.05 pts/m2. >digital surface model: The DSM represents surface elevations including heights of vegetation, buildings, bridges, etc. The DSM is a single band, 32-bit GeoTIFF file, with a ground sample distance of 1 meter. No Data value is set to -3.40282306074e+038. >digital terrain model: The DTM represents surface elevations of ground surfaces, excluding vegetation, bridges, buildings, etc. The DTM is a single-band, 32-bit float GeoTIFF file, with a ground sample distance of 1 meter. No Data value is set to -3.40282306074e+038. >lidar intensity image: The lidar intensity image describes the relative amplitude of reflected signals contributing to the point cloud. Lidar intensity is largely a function of scanned object reflectance in relation to the signal frequency, is dependent on ambient conditions, and is not necessarily consistent between separate scans. The intensity image is a single-band, 32-bit float GeoTIFF file with a ground sample distance of 1 meter. No Data value is set to -3.40282306074e+038 (32-bit, floating-point minimum). >hydro-enforced digital terrain model: The hydro-enforced DTM represents bare earth surfaces which have undergone a selective "flattening" process, where elevation values for any hydrologic features, as well as any hydrologic obstacles (bridges, culverts, etc.), are replaced with neighboring pixel values. The hydro-enforced DTM is a single-band, 32-bit float GeoTIFF file, with a ground sample distance of 1 meter. No Data value is set to -3.40282306074e+038. Theme Global Change Master Directory (GCMD) Science Keywords EARTH SCIENCE > LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION Theme Global Change Master Directory (GCMD) Science Keywords EARTH SCIENCE > LAND SURFACE > TOPOGRAPHY > TERRAIN ELEVATION > DIGITAL ELEVATION/TERRAIN MODEL (DEM) Theme Global Change Master Directory (GCMD) Science Keywords EARTH SCIENCE > OCEANS > COASTAL PROCESSES > COASTAL ELEVATION Theme ISO 19115 Topic Category elevation Theme ISO 19115 Topic Category geoscientificInformation Spatial Global Change Master Directory (GCMD) Location Keywords CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA Spatial Global Change Master Directory (GCMD) Location Keywords CONTINENT > NORTH AMERICA > UNITED STATES OF AMERICA > ALASKA Spatial Global Change Master Directory (GCMD) Location Keywords VERTICAL LOCATION > LAND SURFACE Instrument Global Change Master Directory (GCMD) Instrument Keywords LIDAR > Light Detection and Ranging Platform Global Change Master Directory (GCMD) Platform Keywords Airplane > Airplane Theme Alaska Division of Geological & Geophysical Surveys Debris Avalanche Theme Alaska Division of Geological & Geophysical Surveys Debris Flow Theme Alaska Division of Geological & Geophysical Surveys Glacial Geology Theme Alaska Division of Geological & Geophysical Surveys Glacial Geomorphology Theme Alaska Division of Geological & Geophysical Surveys Glacial Processes Theme Alaska Division of Geological & Geophysical Surveys Landslide Theme Alaska Division of Geological & Geophysical Surveys LiDAR Theme Alaska Division of Geological & Geophysical Surveys Remote Sensing Theme Alaska Division of Geological & Geophysical Surveys Rock Avalanche Theme Alaska Division of Geological & Geophysical Surveys Rockfall Theme Alaska Division of Geological & Geophysical Surveys Slope Instability Theme Alaska Division of Geological & Geophysical Surveys Tsunami Theme Alaska Division of Geological & Geophysical Surveys Unconsolidated Deposits Spatial Alaska Division of Geological & Geophysical Surveys Barry Glacier Spatial Alaska Division of Geological & Geophysical Surveys College Fjord Spatial Alaska Division of Geological & Geophysical Surveys Esther Island Spatial Alaska Division of Geological & Geophysical Surveys Harriman Fjord Spatial Alaska Division of Geological & Geophysical Surveys Passage Canal Spatial Alaska Division of Geological & Geophysical Surveys Port Wells Spatial Alaska Division of Geological & Geophysical Surveys Whittier Office for Coastal Management Charleston SC Data Set Elevation None Planned Model (digital) 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. These data products were funded by the State of Alaska and collected and processed by DGGS. We thank Clearwater Air and Alpine Air for their aviation expertise and contribution to these data products., Daanen, R.P. Wolken, G.J. Wikstrom Jones, Katreen Herbst, A.M. Data Steward 2022 Organization NOAA Office for Coastal Management NOAA/OCM coastal.info@noaa.gov 2234 South Hobson Ave Charleston SC 29405-2413 (843) 740-1202 https://coast.noaa.gov NOAA Office for Coastal Management Home Page Online Resource Distributor 2022 Organization NOAA Office for Coastal Management NOAA/OCM coastal.info@noaa.gov 2234 South Hobson Ave Charleston SC 29405-2413 (843) 740-1202 https://coast.noaa.gov NOAA Office for Coastal Management Home Page Online Resource Metadata Contact 2022 Organization NOAA Office for Coastal Management NOAA/OCM coastal.info@noaa.gov 2234 South Hobson Ave Charleston SC 29405-2413 (843) 740-1202 https://coast.noaa.gov NOAA Office for Coastal Management Home Page Online Resource Point of Contact 2022 Organization NOAA Office for Coastal Management NOAA/OCM coastal.info@noaa.gov 2234 South Hobson Ave Charleston SC 29405-2413 (843) 740-1202 https://coast.noaa.gov NOAA Office for Coastal Management Home Page Online Resource Ground Condition -148.214985 -148.060743 61.188625 61.077423 Discrete 2020-06-26 Yes Vertical EPSG:5703 NAVD88 height North American Vertical Datum 1988 1 Gravity-related height H metre up Projected EPSG:6335 NAD83(2011) / UTM zone 6N NAD83 (National Spatial Reference System 2011) GRS 1980 6378137 298.257222101 NAD83(2011) UTM zone 6N Transverse Mercator 1 Easting E metre east Unclassified Data is available online for bulk and custom downloads. None Users should be aware that temporal changes may have occurred since this data set was collected and some parts of this data may no longer represent actual surface conditions. Users should not use this data for critical applications without a full awareness of its limitations. https://coast.noaa.gov/dataviewer/#/lidar/search/where:ID=9579/details/9579 2022 Organization NOAA Office for Coastal Management Customized Download 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. Zip Zip https://noaa-nos-coastal-lidar-pds.s3.us-east-1.amazonaws.com/dem/AK_Barry_Arm_DEM_2020_9579/index.html 2022 Organization NOAA Office for Coastal Management Bulk Download Bulk download of data files in the original coordinate system. GeoTIFF GeoTIFF https://coast.noaa.gov/ NOAA's Office for Coastal Management (OCM) website Online Resource HTML Information on the NOAA Office for Coastal Management (OCM) https://coast.noaa.gov/dataviewer/ NOAA's Office for Coastal Management (OCM) Data Access Viewer (DAV) Online Resource HTML 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. https://dggs.alaska.gov/webpubs/dggs/rdf/text/rdf2021_003.pdf Lidar Report Online Resource pdf Link to the lidar report. Horizontal accuracy was not measured for this collection. A mean offset of -19.7 cm was measured between 84 control points and the point cloud (appendix 1). This offset was reduced to -0.6 cm by performing a vertical transformation of the lidar point data. Twenty-two check points were used to determine the non-vegetated vertical accuracy (NVA) of the point cloud ground class, using a TIN-based approach. Project NVA was calculated to have a root mean square error (RMSE) of 7.7 cm. See accompanying report for more detail. This data release is complete, and there is no over collect except for aircraft turns that were eliminated from the dataset. Relative accuracy for this dataset was evaluated as the interswath overlap consistency and was measured at 8.3 cm RMSE. The data quality is consistent throughout the survey. Data were collected by the Alaska Division of Geological and Geophysical Surveys (AK DGGS). OCM downloaded the data from the Alaska DGGS Elevation Portal and processed the data to be available for custom and bulk download from the NOAA Digital Coast Data Access Viewer (DAV). Alaska Division of Geological and Geophysical Surveys (AK DGGS) Organization AK DGGS Originator https://elevation.alaska.gov/ AK DGGS Elevation Portal 1 Airborne survey - DGGS used a Riegl VUX1-LR laser scanner integrated with a global navigation satellite system (GNSS) and Northrop Grumman LN-200C inertial measurement unit (IMU). The lidar integration system was designed by Phoenix LiDAR Systems. The sensor is capable of collecting up to 820,000 points per second over a distance of 150 m. This survey was flown with a pulse refresh rate between 200,000 and 600,000 pulses per second at a scan rate between 80 and 150 lines per second. This survey was flown with an average elevation of 200 m above ground level and a ground speed of approximately 36 m/s with a fixed-wing aircraft configuration, using a Cessna 180 aircraft. The scan angle was set from 80 to 280 degrees. The total area surveyed was approximately 40 km2. Flight take-off occurred at 10:15am from Merrill Field airport in Anchorage, Alaska, and landing occurred at 4:00 pm. The aircraft landed at the airstrip in Girdwood, Alaska, once during the survey. 2020-06-26T00:00:00 2 Ground survey - Ground control and check points were collected on June 26, 2020. A Trimble R10-2 GNSS receiver with internal antenna was deployed on the ridge near the center of the study and provided a base station occupation and real-time kinematic (RTK) corrections to points surveyed with a rover Trimble R10-2 GNSS receiver (internal antenna). A total of 106 ground control points and check points were collected to be used for calibration and assessment of the vertical accuracy of the point cloud. All points were collected on bare earth or minimally vegetated surface. 2020-06-26T00:00:00 3 Lidar dataset processing - Point data were processed in SDCimport software for initial filtering and multiple-time-around (MTA) disambiguation. MTA errors, corrected in this process, are the result of imprecise interpretations of received pulse time intervals and occur more frequently with higher pulse refresh rates. Inertial Measurement Unit (IMU) and Global Navigation Satellite System (GNSS) data were processed in Inertial Explorer and used to integrate flightline information with the point cloud in Spatial Explorer software. The point data were calibrated at an incrementally precise scale of sensor movement and behavior, incorporating sensor velocity, roll, pitch, and yaw fluctuations throughout the survey. Points were classified in accordance with American Society for Photogrammetry and Remote Sensing (ASPRS) 2014 guidelines, using macros designed in Terrasolid software. Careful attention was given to the interpolation of the project's ground surface to compensate for inconsistent penetration through low vegetation as a function of the scan angle. Once classified, points underwent a geometric transformation and were converted from ellipsoidal heights to GEOID12B (Alaska) orthometric heights. Raster products were derived from the point cloud using ArcMap. The DTM was interpolated from all ground class returns using a TIN-based method. The DTM was also used to produce a separate hydro-enforced raster based on a digitized shoreline. The DSM was likewise interpolated from only the first return points using a TIN-based method. An intensity image was also produced in ArcMap, using closest-to-mean binning. 2020-01-01T00:00:00 4 The NOAA Office for Coastal Management (OCM) downloaded 1 raster DEM file in GeoTiff format from the Alaska DGGS Elevation Portal. The data were in UTM Zone 6 NAD83 (2011), meters coordinates and NAVD88 (Geoid12B) elevations in meters. The bare earth raster file was at a 1 meter grid spacing. NOAA OCM noted that there are artifact areas along some of the borders of the data set. OCM performed the following processing on the data for Digital Coast storage and provisioning purposes: 1. Used internal an script to assign the EPSG codes (Horizontal EPSG: 6335 and Vertical EPSG: 5703) to the GeoTiff formatted files. 2. Copied the files to https. 2022-09-06T00:00:00 Organization Office for Coastal Management OCM https://ror.org/05v14bq57 2234 South Hobson Avenue Charleston SC 29405-2413 https://www.coast.noaa.gov/ gov.noaa.nmfs.inport:67836 Rebecca Mataosky 2022-09-06T20:43:59 SysAdmin InPortAdmin 2026-03-04T19:17:17 2024-01-10 OCM Partners OCMP 1002 Public No No 2022-09-06 1 Year 2023-09-06