{"action":"create","ckan_id":null,"date_created":"Wed, 25 Feb 2026 05:54:34 GMT","date_finished":null,"harvest_job_id":"eb09b262-e723-4298-b3a7-4ac67ebae5b1","harvest_source_id":"f4c7bbab-c7ef-4277-a7d3-c25b78854814","id":"177bd4f6-39f5-4696-8b29-2bb0e944c91d","identifier":"https://dggs.alaska.gov/webpubs/metadata/RDF2021-6.xml","parent_identifier":null,"source_hash":"6f404b69be1aefccf817bd8da50a21eabda5a130607f8c86da805d34440897a4","source_raw":"\r\n\r\n \r\n \r\n \r\n Salisbury, J.B.\r\n Herbst, A.M.\r\n Daanen, R.P.\r\n 2021\r\n Lidar-derived elevation models for the Grewingk Glacier 1967 landslide scar, Alaska, collected June 3, 2019\r\n report, point cloud, GeoTIFF\r\n \r\n Raw Data File\r\n RDF 2021-6\r\n \r\n \r\n Fairbanks, Alaska, United States\r\n Alaska Division of Geological & Geophysical Surveys\r\n \r\n 7 p.\r\n https://doi.org/10.14509/30599\r\n \r\n \r\n \r\n The Alaska Division of Geological & Geophysical Surveys (DGGS) used lidar to produce digital terrain models (DTM), a digital surface model (DSM), and an intensity model for evaluations of the Grewingk Glacier 1967 landslide scar located above the proglacial lake on the north-facing flank of the glacial valley in Kachemak Bay State Park, Alaska. DGGS capitalized on a data collect (Salisbury and others, 2021) conducted in Homer the same day for a landslide hazard resiliency project. Lidar and Global Navigation Satellite System (GNSS) data were collected on June 3, 2019, and subsequently processed using TerraSolid and ArcGIS. The Alaska Division of Mining, Land, & Water (DMLW) Survey Section conducted a targeted Ground Control Survey for the Homer project on June 19-20, 2019, and we use these ground control data for the Grewingk Glacier dataset across Kachemak Bay. These data are being 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/10.14509/30599).\r\n For evaluations of the Grewingk Glacier 1967 landslide scar located above the proglacial lake on the north-facing flank of the glacial valley in Kachemak Bay State Park, Alaska, DGGS capitalized on a data collect (Salisbury and others, 2021) conducted in Homer the same day.\r\n >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 point spacing is 54.07 cm, and the average point density is 3.42 points per square meter. Elevation surfaces interpolated from areas with a point density of fewer than 2 pts/m2 were designated as \"low confidence areas\" rather than classified as No Data. This decision was made to preserve the visual consistency of the data while remaining forthright about its quality.\t\r\n>digital surface model: The DSM represents surface elevations as they appear to the naked eye, including the heights of vegetation, buildings, bridges, 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.\t\r\n>digital terrain model: The DTM represents surface elevations of ground surfaces, achieved by penetrating or flattening any vegetation, bridges, buildings, and other non-ground features. 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 (the 32-bit, floating-point minimum).\t\r\n>hydro-flattened digital terrain model: The hydro-flattened DTM represents bare earth surfaces that have undergone a selective \"flattening\" process, where elevation values for any hydrologic features are replaced with a consistent, appropriate pixel (elevation) value. The hydro-enforced 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.\t\r\n>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 0.5 meters. No Data value is set to -3.40282306074e+038.\r\n \r\n \r\n \r\n \r\n 20190603\r\n \r\n \r\n ground condition\r\n \r\n \r\n complete\r\n None planned\r\n \r\n \r\n \r\n -151.183077\r\n -151.034593\r\n 59.612907\r\n 59.576673\r\n \r\n \r\n \r\n \r\n ISO 19115 Topic Category\r\n geoscientificInformation\r\n \r\n \r\n Alaska Division of Geological & Geophysical Surveys\r\n\t\tDGGS\r\n Digital Elevation Model\r\n Digital Surface Model (DSM)\r\n Digital Terrain Model\r\n Engineering\r\n Engineering Geology\r\n Glaciers\r\n Landslide\r\n LiDAR\r\n LiDAR Intensity Image\r\n Point Cloud Data\r\n Point Count\r\n Raster Image\r\n \r\n \r\n Alaska Division of Geological & Geophysical Surveys\r\n Grewingk Glacier\r\n Halibut Cove\r\n Kachemak Bay\r\n \r\n \r\n This report, map, and/or dataset is available directly from the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys (see contact information below).\r\n Any hard copies or published datasets utilizing these datasets shall clearly indicate their source. If the user has modified the data in any way, the user is obligated to describe the types of modifications the user has made. The user specifically agrees not to misrepresent these datasets, nor to imply that changes made by the user were approved by the State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys. The State of Alaska makes no express 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.\r\n \r\n \r\n \r\n Alaska Division of Geological & Geophysical Surveys\r\n \r\n Metadata Manager\r\n \r\n mailing and physical\r\n
3354 College Road
\r\n Fairbanks\r\n AK\r\n 99709-3707\r\n USA\r\n \r\n (907)451-5020\r\n (907)451-5050\r\n dggspubs@alaska.gov\r\n 8 am to 4:30 pm, Monday through Friday, except State holidays\r\n Please view our website (https://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible.\r\n \r\n \r\n These data products were funded by the State of Alaska and collected and processed by Alaska Division of Geological & Geophysical Surveys staff. The Homer lidar dataset and ground control referenced above was funded by the Federal Emergency Management Agency (FEMA) through Cooperating Technical Partnership (CTP) with the City of Homer and AK DGGS under federal grant number CTP EMS-2018-CA-00016-S01. We thank Clearwater Air for their aviation expertise and contribution to these data products.\r\n \r\n \r\n Salisbury, J.B.\r\n Daanen, R.P.\r\n Herbst, A.M.\r\n 2021\r\n Lidar-derived elevation models for Homer, Alaska\r\n \r\n Raw Data File\r\n RDF 2021-2\r\n \r\n \r\n Fairbanks, Alaska, United States\r\n Alaska Division of Geological & Geophysical Surveys\r\n \r\n 6 p\r\n https://doi.org/10.14509/30591\r\n \r\n \r\n \r\n \r\n Stevens, D.S.P.\r\n Wolken, G.J.\r\n Hubbard, T.D.\r\n Hendricks, K.A.\r\n 2018\r\n Landslides in Alaska\r\n \r\n Information Circular\r\n IC 65\r\n \r\n \r\n Fairbanks, Alaska, United States\r\n Alaska Division of Geological & Geophysical Surveys\r\n \r\n 2 p\r\n https://doi.org/10.14509/29849\r\n \r\n \r\n \r\n \r\n Stevens, D.S.P.\r\n 2019\r\n The Engineering Geology section at DGGS\r\n \r\n Information Circular\r\n IC 76\r\n \r\n \r\n Fairbanks, Alaska, United States\r\n Alaska Division of Geological & Geophysical Surveys\r\n \r\n 2 p\r\n https://doi.org/10.14509/30122\r\n \r\n \r\n \r\n \r\n Timm, Kristin\r\n Wolken, G.J.\r\n 2017\r\n Deglacierization and the development of glacier-related hazards\r\n \r\n Information Circular\r\n IC 63\r\n \r\n \r\n Fairbanks, Alaska, United States\r\n Alaska Division of Geological & Geophysical Surveys\r\n \r\n 3 p\r\n https://doi.org/10.14509/29752\r\n \r\n \r\n \r\n \r\n \r\n Not applicable\r\n \r\n Elevation surfaces interpolated from areas with a point density of fewer than 2 pts/m2 were designated as 'low confidence areas' rather than classified as nodata. This decision was made to preserve the visual consistency of the data while remaining forthright about its quality. The tests and processing methods used to ensure data consistency are further described in the accompanying report.\r\n This is a partial release dataset. Data for the Grewingk Glacier 1967 landslide scar were collected at the end of the day (June 3, 2019), after collection of Homer data was complete and the plane was refueled. Data quality portrayed here is based on the Homer dataset, as we have no ground control across Kachemak Bay. However, we ran the lidar scanner continuously all day and quality should be consistent throughout the Homer and Grewingk datasets.\r\n \r\n \r\n Horizontal accuracy was not measured for this collection.\r\n \r\n \r\n No ground control was collected for this dataset. However, these data share relative accuracy properties with another dataset in Homer, for which an RMSE of 3.1 cm was evaluated. The relative accuracy between these two datasets was measured at 1.18 cm RMSE, calculated as the inter-swath consistency. See accompanying report for more detail.\r\n \r\n \r\n \r\n \r\n Airborne survey - DGGS operates a Riegl VUX1-LR laser scanner with a GNSS and Northrop Grumman Inertial Measurement Unit (IMU). The integration was designed by Phoenix LiDAR systems. The sensor can collect up to 820,000 points per second over a 150 m range. We flew the instrument with a repetition rate of 400,000 to 820,000 pulses per second, a scan speed of 200 revolutions per second, at approximately 150 m above ground level, and at a ground speed of approximately 40 meters per second with a fixed-wing Cessna 185. The scan look angle operated between 55 and 305 degrees. The total data coverage is approximately 16.31 km2. DGGS collected lidar data in the Homer area on June 3, 2019, initiating the GNSS base station at 8:48 am and flying from 10:15 am to 3:35 pm with a 15-minute refuel at 2:15 pm. Data for the Grewingk Glacier landslide scar were collected in the afternoon from 2:30 pm to 3:35 pm after the plane refuel stop. The sky was clear with light, easterly winds. Patchy snow cover was present along the ridgeline during the survey.\r\n 20190603\r\n \r\n \r\n Ground survey - The Alaska Division of Mining, Land, & Water Survey Section collected 79 points in a targeted Ground Control Survey in Homer on June 19-20, 2019. We use these ground control data for the Grewingk dataset, as the lidar collection was continuous from one study area to the next.\r\n 20190603\r\n \r\n \r\n Lidar dataset processing - DGGS processed raw data by first using SDCImport to apply range thresholding, reflectance thresholding, and missed-time-around (MTA) disambiguation for preliminary point cloud noise filtering. We coupled in-flight IMU and GNSS data in Inertial Explorer to produce flight trajectory data and coupled the trajectory data with the raw point cloud in Spatial Explorer. We then used Terrasolid to calibrate point cloud data using tielines for roll, pitch, and yaw of the aircraft during the survey. We completed this process first for all points, then on a per-flight-line basis. For additional calibration, we identified interswath fluctuations in preliminarily classified ground points using overlapping tielines. We classified the point cloud in accordance with American Society for Photogrammetry and Remote Sensing (ASPRS) guidelines using project-tailored macros, resulting in a ground points class, as well as low, medium, and high vegetation (0.01-0.3 m, 0.3-5 m, and 5-60 m heights above the ground, respectively). Misclassified points were manually reclassified in post-processing QA/QC. We eliminated all low points and air points from the dataset. We converted the point cloud from ellipsoidal to orthometric heights using GEOID 12B and then uniformly vertically adjusted the dataset (based on ground control collected in Homer) to minimize vertical offset. All derivative products were created in ArcMap. The 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. A lidar intensity image was created from first returns of all classes using mean binning.\r\n 2020\r\n \r\n \r\n \r\n \r\n raster\r\n \r\n \r\n \r\n \r\n \r\n Universal Transverse Mercator\r\n \r\n 5\r\n \r\n 0.999600\r\n -153\r\n 0\r\n 500000.000000\r\n 0\r\n \r\n \r\n \r\n \r\n coordinate pair\r\n \r\n .00000001\r\n .00000001\r\n \r\n Meters\r\n \r\n \r\n \r\n NAD83\r\n GRS 80\r\n 6378137\r\n 298.257222101000025\r\n \r\n \r\n \r\n \r\n NAVD88, GEOID12B\r\n 0.001\r\n meters\r\n Explicit elevation coordinate included with horizontal coordinates\r\n \r\n \r\n \r\n \r\n \r\n \r\n classified point cloud data\r\n 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 point spacing is 54.07 cm, and the average point density is 3.42 points per square meter. Elevation surfaces interpolated from areas with a point density of fewer than 2 pts/m2 were designated as \"low confidence areas\" rather than classified as No Data. This decision was made to preserve the visual consistency of the data while remaining forthright about its quality.\r\n DGGS\r\n classified point cloud data\r\n \r\n \r\n \r\n \r\n digital surface model\r\n The DSM represents surface elevations as they appear to the naked eye, including the heights of vegetation, buildings, bridges, 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.\r\n DGGS\r\n digital surface model\r\n \r\n \r\n \r\n \r\n digital terrain model\r\n The DTM represents surface elevations of ground surfaces, achieved by penetrating or flattening any vegetation, bridges, buildings, and other non-ground features. 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 (the 32-bit, floating-point minimum).\r\n DGGS\r\n digital terrain model\r\n \r\n \r\n \r\n \r\n hydro-flattened digital terrain model\r\n The hydro-flattened DTM represents bare earth surfaces that have undergone a selective \"flattening\" process, where elevation values for any hydrologic features are replaced with a consistent, appropriate pixel (elevation) value. The hydro-enforced 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.\r\n DGGS\r\n hydro-flattened digital terrain model\r\n \r\n \r\n \r\n \r\n lidar intensity image\r\n 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 0.5 meters. No Data value is set to -3.40282306074e+038.\r\n DGGS\r\n lidar intensity image\r\n \r\n \r\n \r\n \r\n \r\n \r\n \r\n Alaska Division of Geological & Geophysical Surveys\r\n \r\n Metadata Manager\r\n \r\n mailing and physical\r\n
3354 College Road
\r\n Fairbanks\r\n AK\r\n 99709-3707\r\n USA\r\n \r\n (907)451-5020\r\n (907)451-5050\r\n dggspubs@alaska.gov\r\n 8 am to 4:30 pm, Monday through Friday, except State holidays\r\n Please view our website (https://www.dggs.alaska.gov) for the latest information on available data. Please contact us using the e-mail address provided above when possible.\r\n \r\n \r\n RDF 2021-6\r\n 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.\r\n \r\n DGGS publications are available as free online downloads or you may purchase paper hard-copies or digital files on CD/DVD or other digital storage media by mail, phone, fax, or email from the DGGS Fairbanks office. To purchase this or other printed reports and maps, contact DGGS by phone (907-451-5020), e-mail (dggspubs@alaska.gov), or fax (907-451-5050). Payment accepted: Cash, check, money order, VISA, or MasterCard. Turnaround time is 1-2 weeks unless special arrangements are made and an express fee is paid. Shipping charge will be the actual cost of postage and will be added to the total amount due. Contact us for the exact shipping amount.\r\n Contact DGGS for current pricing\r\n \r\n \r\n \r\n \r\n report point-cloud GeoTIFF\r\n 20210323\r\n classified point cloud data, digital surface model, digital terrain model, hydro-flattened digital terrain model, and lidar intensity image\r\n \r\n \r\n \r\n \r\n \r\n https://doi.org/10.14509/30599\r\n \r\n \r\n \r\n \r\n \r\n Free download\r\n \r\n \r\n \r\n 20210324\r\n \r\n \r\n \r\n Alaska Division of Geological & Geophysical Surveys\r\n Simone Montayne\r\n \r\n Metadata Manager\r\n \r\n mailing and physical\r\n
3354 College Road
\r\n Fairbanks\r\n AK\r\n 99709-3707\r\n USA\r\n \r\n (907)451-5020\r\n (907)451-5050\r\n dggspubs@alaska.gov\r\n 8 am to 4:30 pm, Monday through Friday, except State holidays\r\n \r\n \r\n FGDC Content Standard for Digital Geospatial Metadata\r\n FGDC-STD-001-1998\r\n If the user has modified the data in any way they are obligated to describe the types of modifications they have performed in the supporting metadata file. User specifically agrees not to imply that changes they made were approved by the Alaska Department of Natural Resources or Division of Geological & Geophysical Surveys.\r\n \r\n https://dggs.alaska.gov/metadata/dggs.ext\r\n dggs metadata extensions\r\n \r\n \r\n\r\n","source_transform":null,"status":"error"}