Identification_Information: Citation: Citation_Information: Originator: Zechmann, J.M. Originator: Wikstrom Jones, Katreen Originator: Wolken, G.J. Publication_Date: 2023 Title: Lidar-derived elevation data for land near Grewingk Glacier and Halibut Cove Lagoon, Southcentral Alaska, collected October 12-13, 2021 Geospatial_Data_Presentation_Form: data Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2023-2 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 11 p. Online_Linkage: https://doi.org/10.14509/30958 Description: Abstract: Lidar-derived elevation data for land near Grewingk Glacier and Halibut Cove Lagoon, Southcentral Alaska, collected October 12-13, 2021, Raw Data File 2023-2, uses aerial lidar to produce a classified point cloud, digital surface model (DSM), digital terrain models (DTM), and intensity model of land near Grewingk Glacier and Halibut Cove Lagoon, located in Southcentral Alaska (cover figure). Aerial data were collected October 12-13, 2021, and subsequently processed in a suite of geospatial processing software. Ground control data were collected on October 12, 2021. This data supports a paraglacial rock slope destabilization study at Grewingk Glacier and Grewingk Lake and will be used to assess and characterize an ongoing landslide hazard. All files can be downloaded from the Alaska Division of Geological & Geophysical Surveys website (http://doi.org/10.14509/30958). Purpose: This data supports a paraglacial rock slope destabilization study at Grewingk Glacier and Grewingk Lake and will be used to assess and characterize an ongoing landslide hazard. Supplemental_Information: >classified_points: Classified point cloud data are provided in compressed LAZ format. Data are classified in accordance with ASPRS 2019 guidelines (table 1) and contain return and intensity information. For ground points, the average pulse spacing is 52 cm, and the average point density is 3.69 pts/m2. >dsm: The DSM represents surface elevations, including heights of vegetation, buildings, powerlines, etc. The DSM is a single-band, 32-bit GeoTIFF file of 1-meter resolution. No Data value is set to -3.40282306074e+38 (32-bit, floating-point minimum). >dtm: The DTM represent bare earth elevations, excluding vegetation, bridges, buildings, etc. the DTM is single-band, 32-bit float GeoTIFF file, of 1-meter resolution. No Data value is set to -9999. >dtm_detail: The detailed DTM represents bare earth elevations, excluding vegetation. The DTM is single-band, 32-bit float GeoTIFF file, of 20-cm resolution. This higher-resolution DTM file covers an area identified as a scientific priority. No Data value is set to -9999. >lidar_intensity: The lidar intensity image depicts the relative amplitude of reflected signals contributing to the point cloud. Lidar intensity is primarily 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 of 1-meter resolution. No Data value is set to -3.40282306074e+38. >lidar_las_index: The LAS index file is a shapefile with polygons that serve as an index to the spatial location and extent of each point cloud (LAS) bin. Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 20221012 Ending_Date: 20221013 Currentness_Reference: ground condition Status: Progress: complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -151.232799 East_Bounding_Coordinate: -150.928405 North_Bounding_Coordinate: 59.691498 South_Bounding_Coordinate: 59.493974 Keywords: Theme: Theme_Keyword_Thesaurus: ISO 19115 Topic Category Theme_Keyword: geoscientificInformation Theme: Theme_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Theme_Keyword: Aerial Theme_Keyword: Aerial Geology Theme_Keyword: DGGS Theme_Keyword: Digital Elevation Model Theme_Keyword: Digital Surface Model (DSM) Theme_Keyword: Elevation Theme_Keyword: Environmental Theme_Keyword: Geomorphology Theme_Keyword: Geotechnical Theme_Keyword: Glacial Geology Theme_Keyword: Glacial Geomorphology Theme_Keyword: Glacial Processes Theme_Keyword: Glaciers Theme_Keyword: Glaciology Theme_Keyword: Hazards Theme_Keyword: Hydrology and Surficial Geology Theme_Keyword: Landslide Theme_Keyword: LiDAR Theme_Keyword: LiDAR Intensity Image Theme_Keyword: Periglacial Slope Failure Theme_Keyword: Point Cloud Data Theme_Keyword: Point Count Theme_Keyword: Slope Theme_Keyword: Slope Instability Place: Place_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Place_Keyword: China Poot Lake Place_Keyword: Cook Inlet Place_Keyword: Glacier Spit Place_Keyword: Grewingk Creek Place_Keyword: Grewingk Glacier Place_Keyword: Halibut Cove Place_Keyword: Halibut Creek Place_Keyword: Homer Place_Keyword: Humpy Creek Place_Keyword: Kachemak Bay Place_Keyword: Kachemak Bay State Park Place_Keyword: Quiet Creek Place_Keyword: Southcentral Alaska Temporal: Temporal_Keyword_Thesaurus: Walker, J.D., Geissman, J.W., Bowring, S.A, and Babcock, L.E., comp., 2012, Geologic Time Scale v. 4.0: Geological Society of America Temporal_Keyword: Holocene 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: The area of this survey is on the traditional homelands of the Dena'ina people. These data products were funded by RWTH-Aachen University through a grant from the German Research Foundation and the State of Alaska and collected and processed by DGGS. We are grateful to Bretwood 'Hig' Higman for assistance with ground-based surveying. We also thank Clearwater Air for their aviation expertise and contribution to these data products. The views and conclusions contained in this document are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government. 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: 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 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 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Not applicable Logical_Consistency_Report: This is a complete release dataset. There was no over-collect except for aircraft turns that were eliminated from the dataset. The data quality is consistent throughout the survey, save for two small (~0.1 km2) data gaps located along Halibut Creek and in the southeast corner of the study area. Completeness_Report: This data relaease is complete. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: We did not measure horizontal accuracy for this collection. Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: We achieved a vertical accuracy of 3.9 cm average magnitude offset between the lidar point cloud and 178 ground control points by performing a rubbersheet correction. In addition, we evaluated the relative accuracy for this dataset as the interswath overlap consistency and measured it at 8.0 cm RMSE. Lineage: Process_Step: Process_Description: Aerial photogrammetric 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 can collect up to 820,000 points per second at a range of up to 150 m. The scanner operated with a pulse refresh rate of 100,000 pulses per second in alpine areas and up to 600,000 pulses per second over forested areas at a scan rate between 100 and 200 lines per second. We used a Cessna 180 fixed-wing platform to survey from an elevation of ~100-500 m above ground level, at a ground speed of ~37 m/s, and with a scan angle set from 80 to 280 degrees. The total survey area covers ~145 km2. On October 12, we departed Homer Airport at 1:20 pm and covered the Grewingk valley from Kachemak Bay to the lower Grewingk Glacier (fig. 1). We landed back at Homer Airport at 4:15 pm. On October 13, we departed Homer Airport at 10:00 am and covered a swath from Halibut Cove and lower Halibut Creek south to the river that drains Wosnesenski Glacier. Our return time to Homer Airport was 1:30 pm. The weather throughout the survey was partly cloudy to overcast. Process_Date: 20221013 Process_Step: Process_Description: Ground survey - We collected ground control and checkpoints on October 12, 2021. We deployed a Trimble R10-2 GNSS receiver with an internal antenna at a temporary benchmark on the Grewingk Glacier fan delta (59 degrees 38 minutes 27.39 seconds N; 151 degrees 12 minutes 13.338 seconds W). It provided a base station occupation and real-time kinematic (RTK) corrections to points we surveyed with a rover Trimble R10-2 GNSS receiver (internal antenna). We collected a total of 178 ground control and checkpoints for calibration and to assess the vertical accuracy of the point cloud. All points were collected on bare earth. Process_Date: 20221012 Process_Step: Process_Description: Lidar dataset processing - We processed point data in SDCimport software for initial filtering and multiple-time-around (MTA) disambiguation. MTA errors, corrected in this process, result from ambiguous interpretations of received pulse time intervals and occur more frequently with higher pulse refresh rates. We processed Inertial Measurement Unit (IMU) and Global Navigation Satellite System (GNSS) data in Inertial Explorer, and we used Spatial Explorer software to integrate flightline information with the point cloud. We calibrated the point data at an incrementally precise scale of sensor movement and behavior, incorporating sensor velocity, roll, pitch, and yaw fluctuations throughout the survey. We created macros in Terrasolid software and classified points in accordance with American Society for Photogrammetry and Remote Sensing (ASPRS) 2019 guidelines. Once classified, we applied a geometric transformation and converted the points from ellipsoidal heights to GEOID12B (Alaska) orthometric heights. We used ArcGIS Pro to derive raster products from the point cloud. The DSM was interpolated from maximum return values from the ground, vegetation, and building classes using a binning method. The 1-meter DTM was interpolated from all ground class returns, also using a binning method and minimum values. An additional 20-cm DTM encompassing the northern part of the study area (dashed line in cover image) was produced using triangulation with natural neighbor interpolation. In ArcGIS Pro, we created a 1-meter intensity image by binning and averaging ground, vegetation, and building classes. Using the ArcGIS Pro Pixel Editor, we hydroflattened both DTMs and the DSM. Water surface elevations were preserved where possible, and interpolation artifacts were replaced with average water surface elevations and smoothed using the Pixel Editor blur tool. Process_Date: 2022 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 (2011) Ellipsoid_Name: GRS 80 Semi-major_Axis: 6378137 Denominator_of_Flattening_Ratio: 298.257222101 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_points Entity_Type_Definition: Classified point cloud data are provided in compressed LAZ format. Data are classified in accordance with ASPRS 2019 guidelines (table 1) and contain return and intensity information. For ground points, the average pulse spacing is 52 cm, and the average point density is 3.69 pts/m2. Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: classified_points Detailed_Description: Entity_Type: Entity_Type_Label: dsm Entity_Type_Definition: The DSM represents surface elevations, including heights of vegetation, buildings, powerlines, etc. The DSM is a single-band, 32-bit GeoTIFF file of 1-meter resolution. No Data value is set to -3.40282306074e+38 (32-bit, floating-point minimum). Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: dsm Detailed_Description: Entity_Type: Entity_Type_Label: dtm Entity_Type_Definition: The DTM represent bare earth elevations, excluding vegetation, bridges, buildings, etc. the DTM is single-band, 32-bit float GeoTIFF file, of 1-meter resolution. No Data value is set to -9999. Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: dtm Detailed_Description: Entity_Type: Entity_Type_Label: dtm_detail Entity_Type_Definition: The detailed DTM represents bare earth elevations, excluding vegetation. The DTM is single-band, 32-bit float GeoTIFF file, of 20-cm resolution. This higher-resolution DTM file covers an area identified as a scientific priority. No Data value is set to -9999. Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: dtm_detail Detailed_Description: Entity_Type: Entity_Type_Label: lidar_intensity Entity_Type_Definition: The lidar intensity image depicts the relative amplitude of reflected signals contributing to the point cloud. Lidar intensity is primarily 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 of 1-meter resolution. No Data value is set to -3.40282306074e+38. Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: lidar_intensity Detailed_Description: Entity_Type: Entity_Type_Label: lidar_las_index Entity_Type_Definition: The LAS index file is a shapefile with polygons that serve as an index to the spatial location and extent of each point cloud (LAS) bin. Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: lidar_las_index 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 2023-2 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: data Format_Version_Date: 20230406 Format_Information_Content: classified points, dsm, dtm, dtm detail, lidar intensity and lidar las index Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.14509/30958 Fees: Free download Metadata_Reference_Information: Metadata_Date: 20230406 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