Identification_Information: Citation: Citation_Information: Originator: Salisbury, J.B. Originator: Herbst, A.M. Originator: Daanen, R.P. Publication_Date: 2021 Title: Lidar-derived elevation models for the Grewingk Glacier 1967 landslide scar, Alaska, collected June 3, 2019 Geospatial_Data_Presentation_Form: report, point cloud, GeoTIFF Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2021-6 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 7 p. Online_Linkage: https://doi.org/10.14509/30599 Description: Abstract: 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). Purpose: 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. Supplemental_Information: >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. >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. >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). >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. >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. Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 20190603 Currentness_Reference: ground condition Status: Progress: complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -151.183077 East_Bounding_Coordinate: -151.034593 North_Bounding_Coordinate: 59.612907 South_Bounding_Coordinate: 59.576673 Keywords: Theme: Theme_Keyword_Thesaurus: ISO 19115 Topic Category Theme_Keyword: geoscientificInformation Theme: Theme_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Theme_Keyword: DGGS Theme_Keyword: Digital Elevation Model Theme_Keyword: Digital Surface Model (DSM) Theme_Keyword: Digital Terrain Model Theme_Keyword: Engineering Theme_Keyword: Engineering Geology Theme_Keyword: Glaciers Theme_Keyword: Landslide Theme_Keyword: LiDAR Theme_Keyword: LiDAR Intensity Image Theme_Keyword: Point Cloud Data Theme_Keyword: Point Count Theme_Keyword: Raster Image Place: Place_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Place_Keyword: Grewingk Glacier Place_Keyword: Halibut Cove Place_Keyword: Kachemak Bay Access_Constraints: 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). Use_Constraints: 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. Point_of_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: Alaska Division of Geological & Geophysical Surveys Contact_Position: Metadata Manager Contact_Address: Address_Type: mailing and physical Address: 3354 College Road City: Fairbanks State_or_Province: AK Postal_Code: 99709-3707 Country: USA Contact_Voice_Telephone: (907)451-5020 Contact_Facsimile_Telephone: (907)451-5050 Contact_Electronic_Mail_Address: dggspubs@alaska.gov Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays Contact_Instructions: 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. Data_Set_Credit: 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. Cross_Reference: Citation_Information: Originator: Salisbury, J.B. Originator: Daanen, R.P. Originator: Herbst, A.M. Publication_Date: 2021 Title: Lidar-derived elevation models for Homer, Alaska Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2021-2 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 6 p Online_Linkage: https://doi.org/10.14509/30591 Cross_Reference: Citation_Information: Originator: Stevens, D.S.P. Originator: Wolken, G.J. Originator: Hubbard, T.D. Originator: Hendricks, K.A. Publication_Date: 2018 Title: Landslides in Alaska Series_Information: Series_Name: Information Circular Issue_Identification: IC 65 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 2 p Online_Linkage: https://doi.org/10.14509/29849 Cross_Reference: Citation_Information: Originator: Stevens, D.S.P. Publication_Date: 2019 Title: The Engineering Geology section at DGGS Series_Information: Series_Name: Information Circular Issue_Identification: IC 76 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 2 p Online_Linkage: https://doi.org/10.14509/30122 Cross_Reference: Citation_Information: Originator: Timm, Kristin Originator: Wolken, G.J. Publication_Date: 2017 Title: Deglacierization and the development of glacier-related hazards Series_Information: Series_Name: Information Circular Issue_Identification: IC 63 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 3 p Online_Linkage: https://doi.org/10.14509/29752 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Not applicable Logical_Consistency_Report: 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. Completeness_Report: 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. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Horizontal accuracy was not measured for this collection. Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: 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. Lineage: Process_Step: Process_Description: 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. Process_Date: 20190603 Process_Step: Process_Description: 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. Process_Date: 20190603 Process_Step: Process_Description: 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. Process_Date: 2020 Spatial_Data_Organization_Information: Direct_Spatial_Reference_Method: raster Spatial_Reference_Information: Horizontal_Coordinate_System_Definition: Planar: Grid_Coordinate_System: Grid_Coordinate_System_Name: Universal Transverse Mercator Universal_Transverse_Mercator: UTM_Zone_Number: 5 Transverse_Mercator: Scale_Factor_at_Central_Meridian: 0.999600 Longitude_of_Central_Meridian: -153 Latitude_of_Projection_Origin: 0 False_Easting: 500000.000000 False_Northing: 0 Planar_Coordinate_Information: Planar_Coordinate_Encoding_Method: coordinate pair Coordinate_Representation: Abscissa_Resolution: .00000001 Ordinate_Resolution: .00000001 Planar_Distance_Units: Meters Geodetic_Model: Horizontal_Datum_Name: NAD83 Ellipsoid_Name: GRS 80 Semi-major_Axis: 6378137 Denominator_of_Flattening_Ratio: 298.257222101000025 Vertical_Coordinate_System_Definition: Altitude_System_Definition: Altitude_Datum_Name: NAVD88, GEOID12B Altitude_Resolution: 0.001 Altitude_Distance_Units: meters Altitude_Encoding_Method: Explicit elevation coordinate included with horizontal coordinates Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Type_Label: classified point cloud data Entity_Type_Definition: 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. Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: classified point cloud data Detailed_Description: Entity_Type: Entity_Type_Label: digital surface model Entity_Type_Definition: 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. Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: digital surface model Detailed_Description: Entity_Type: Entity_Type_Label: digital terrain model Entity_Type_Definition: 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). Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: digital terrain model Detailed_Description: Entity_Type: Entity_Type_Label: hydro-flattened digital terrain model Entity_Type_Definition: 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. Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: hydro-flattened digital terrain model Detailed_Description: Entity_Type: Entity_Type_Label: lidar intensity image Entity_Type_Definition: 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. Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: lidar intensity image Distribution_Information: Distributor: Contact_Information: Contact_Organization_Primary: Contact_Organization: Alaska Division of Geological & Geophysical Surveys Contact_Position: Metadata Manager Contact_Address: Address_Type: mailing and physical Address: 3354 College Road City: Fairbanks State_or_Province: AK Postal_Code: 99709-3707 Country: USA Contact_Voice_Telephone: (907)451-5020 Contact_Facsimile_Telephone: (907)451-5050 Contact_Electronic_Mail_Address: dggspubs@alaska.gov Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays Contact_Instructions: 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. Resource_Description: RDF 2021-6 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. Standard_Order_Process: Non-digital_Form: 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. Fees: Contact DGGS for current pricing Standard_Order_Process: Digital_Form: Digital_Transfer_Information: Format_Name: report point-cloud GeoTIFF Format_Version_Date: 20210323 Format_Information_Content: classified point cloud data, digital surface model, digital terrain model, hydro-flattened digital terrain model, and lidar intensity image Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.14509/30599 Fees: Free download Metadata_Reference_Information: Metadata_Date: 20210324 Metadata_Contact: Contact_Information: Contact_Organization_Primary: Contact_Organization: Alaska Division of Geological & Geophysical Surveys Contact_Person: Simone Montayne Contact_Position: Metadata Manager Contact_Address: Address_Type: mailing and physical Address: 3354 College Road City: Fairbanks State_or_Province: AK Postal_Code: 99709-3707 Country: USA Contact_Voice_Telephone: (907)451-5020 Contact_Facsimile_Telephone: (907)451-5050 Contact_Electronic_Mail_Address: dggspubs@alaska.gov Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays Metadata_Standard_Name: FGDC Content Standard for Digital Geospatial Metadata Metadata_Standard_Version: FGDC-STD-001-1998 Metadata_Use_Constraints: 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. Metadata_Extensions: Online_Linkage: https://dggs.alaska.gov/metadata/dggs.ext Profile_Name: dggs metadata extensions