Identification_Information: Citation: Citation_Information: Originator: Zechmann, J.M. Originator: Wikstrom Jones, K.M. Originator: Wolken, G.J. Publication_Date: 2023 Title: Lidar-derived elevation data for Wrangell Island, Southeast Alaska, collected July 2023 Geospatial_Data_Presentation_Form: data Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2023-28 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 14 p. Online_Linkage: https://doi.org/10.14509/31098 Description: Abstract: Lidar-derived elevation data for Wrangell Island, Southeast Alaska, collected July 2023, Raw Data File 2023-28, provides lidar-derived classified point cloud, a digital surface model (DSM), a digital terrain model (DTM), and an intensity model of Wrangell Island, Southeast Alaska, during leaf-on ground conditions. The survey provides snow-free surface elevations for use in shoreline development, resource quantification, hydrographic mapping, and slope stability modeling. Ground control data were collected June 26-30, 2023, and aerial lidar data were collected July 7-11, 2023, and subsequently merged and processed using a suite of geospatial processing software. All files can be downloaded from the Alaska Division of Geological & Geophysical Surveys website (http://doi.org/10.14509/31098). Purpose: The survey provides snow-free surface elevations for use in shoreline development, resource quantification, hydrographic mapping, and slope stability modeling. Supplemental_Information: >boundaries: A boundary, also known as an Area of Interest (AOI) or border, that defines the area covered by the data. >classified_points: Classified point cloud data are provided in LASer (LAS) format. Data are classified following ASPRS 2019 guidelines (table 2) and contain return and intensity information. For all ground points, the average point spacing is 54.6 cm, and the average density is 3.35 pts/m2. >dsm: The DSM represents surface elevations, including heights of vegetation, buildings, powerlines, bridge decks, etc. The DSM is a single-band, 32-bit GeoTIFF file of 50-cm resolution. No Data value is set to -9999. >dtm: The DTM represents bare earth elevations, excluding vegetation, bridge decks, buildings, etc. The DTM is a single-band, 32-bit GeoTIFF file of 50-cm resolution. No Data value is set to -9999. >lidar_intensity: The lidar intensity image describes the relative amplitude of reflected signals contributing to the point cloud. Lidar intensity is (1) primarily a function of scanned object reflectance in relation to the signal frequency, (2) dependent on ambient conditions, and (3) not necessarily consistent between separate scans. The intensity image is a single-band, 16-bit unsigned GeoTIFF file of 50-cm resolution. No Data value is set to 0. Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 20230626 Ending_Date: 20230711 Currentness_Reference: ground condition Status: Progress: complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -132.396167 East_Bounding_Coordinate: -131.920007 North_Bounding_Coordinate: 56.494219 South_Bounding_Coordinate: 56.115756 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: Aerial Photography Theme_Keyword: Coastal Theme_Keyword: Coastal and River Theme_Keyword: DGGS Theme_Keyword: Digital Elevation Model Theme_Keyword: Digital Surface Model (DSM) Theme_Keyword: Digital Terrain Model Theme_Keyword: Elevation Theme_Keyword: Emergency Preparedness Theme_Keyword: Engineering Theme_Keyword: Engineering Geology Theme_Keyword: Environmental Theme_Keyword: Geologic Theme_Keyword: Geologic Hazards Theme_Keyword: Geological Process Theme_Keyword: Geology Theme_Keyword: Geomorphology Theme_Keyword: Geotechnical Theme_Keyword: Hazards Theme_Keyword: Hillshade Image Theme_Keyword: LiDAR Theme_Keyword: LiDAR Intensity Image Theme_Keyword: LiDAR LAS File Format Theme_Keyword: Point Cloud Data Theme_Keyword: Raster Image Theme_Keyword: Remote Sensing Theme_Keyword: Slope Theme_Keyword: Surface Theme_Keyword: Surficial Theme_Keyword: Surficial Geology Theme_Keyword: Topography Theme_Keyword: Water Place: Place_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Place_Keyword: Blake Channel Place_Keyword: Bradfield Canal Place_Keyword: Cemetery Point Place_Keyword: Chichagof Peak Place_Keyword: Dewey Hill Place_Keyword: Double Rock Place_Keyword: Eastern Passage Place_Keyword: Ernest Sound Place_Keyword: Highbush Lake Place_Keyword: Institute Creek Place_Keyword: Long Lake Place_Keyword: McCormack Creek Place_Keyword: Nemo Point Place_Keyword: Pat Creek Place_Keyword: Pats Lake Place_Keyword: Point Highfield Place_Keyword: Point Shekesti Place_Keyword: Rainbow Falls Place_Keyword: Shoemaker Bay Place_Keyword: Southeast Alaska Place_Keyword: The Narrows Place_Keyword: Thoms Creek Place_Keyword: Thoms Lake Place_Keyword: Thoms Point Place_Keyword: Trout Lake Place_Keyword: Turn Island Place_Keyword: Turn Point Place_Keyword: Wrangell Place_Keyword: Wrangell Harbor Place_Keyword: Wrangell Island Place_Keyword: Zimovia Islets Place_Keyword: Zimovia Strait 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: This survey area is on the traditional homelands of the Stikine Tlingit people. For this project, we partnered with the U.S. Forest Service to cost-share the acquisition of lidar data in an area of mutual interest. We thank Clearwater Air for their aviation expertise and contribution to these data products, Dustin Wittwer and Joe Delabrue of the U.S. Forest Service for logistical help, and David Ciampa and Amy Helkenn of the Alaska Division of Mining, Land and Water for providing ground control points. 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: 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: 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 Cross_Reference: Citation_Information: Originator: Wolken, G.J. Originator: Hendricks, K.A. Originator: Daanen, R.P. Originator: Overbeck, J.R. Originator: Stevens, D.S.P. Originator: Masterman, S.S. Publication_Date: 2017 Title: Alaska & climate change Series_Information: Series_Name: Information Circular Issue_Identification: IC 64 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/10.14509/29781 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Not applicable Logical_Consistency_Report: This is a full-release dataset. There was no over-collect. Data quality is consistent throughout the survey. 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 measured a mean offset of +94.3 cm between 43 control points and the point cloud. This offset was reduced to +0.9 cm in non-vegetated areas and +10.5 cm in vegetated areas by applying a rubber-sheet vertical correction to the lidar point data. We used 214 checkpoints to determine the vertical accuracy of the point cloud ground class using a Triangulated Irregular Network (TIN) approach. The project vertical accuracy has a root mean square error (RMSE) of 5.3 cm in non-vegetated areas and 17.4 cm in vegetated areas (app. 3). We evaluated the relative accuracy for this dataset as the interswath overlap consistency and measured it at 6.4 cm RMSE. Lineage: Process_Step: Process_Description: Ground survey - Ground control points were collected June 26-30, 2023, by the Alaska Division of Mining, Land and Water (DMLW). They deployed a Trimble R12 GNSS receiver to provide a base station occupation and real-time kinematic (RTK) corrections to points they surveyed with a rover Trimble R12i GNSS receiver/TSC5 controller. Benchmark HH-2 (PID BBDX58), located on the Heritage Harbor breakwater in Wrangell, served as the base station location. DMLW collected 43 ground control points and 214 checkpoints to use for calibration and assess the vertical accuracy of the point cloud. Checkpoints were collected in forest, shrubland, grassland, sphagnum bog, bare earth, and paved surfaces. We processed and delivered all data in NAD83 (2011) UTM8N and vertical datum NAVD88 GEOID12B. Process_Date: 20230630 Process_Step: Process_Description: Aerial photogrammetric survey - DGGS used a Riegl VUX1-LR22 laser scanner integrated with a global navigation satellite system (GNSS) and Northrop Grumman LN-200C inertial measurement unit (IMU) designed by Phoenix LiDAR Systems. The sensor can collect a maximum of 1,500,000 points per second at a range of 150 m, or a minimum of 50,000 points per second at a range of 640 m. The scanner operated with a pulse refresh rate of 600,000 pulses per second over forested terrain, and 200,000 pulses per second over alpine terrain, with a scan rate between 50 and 200 lines per second. We used a Cessna 180 fixed-wing platform to survey from an elevation of approximately 150-350 m above ground level, at a ground speed of approximately 40 m/s, and with a scan angle set from 80 to 280 degrees. The total survey area covers approximately 565 km2. The survey area was accessed by air from Wrangell Airport. See table 1 of the accompanying report for data collection start and end times, and weather conditions. Process_Date: 20230711 Process_Step: Process_Description: Lidar dataset processing - We processed point data in Spatial Explorer 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 IMU and GNSS data in Inertial Explorer, and flightline information was integrated with the point cloud in Spatial Explorer. 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 the American Society for Photogrammetry & Remote Sensing (ASPRS) 2019 guidelines (ASPRS, 2019). 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. A 50-cm DSM was interpolated from maximum return values from ground, vegetation, bridge deck, and building classes using a binning method and maximum values. A 50-cm DTM was interpolated from all ground class returns using a binning method and minimum values. We also produced an intensity image for the entire area using average binning in ArcGIS Pro, with no normalization or corrections applied. Process_Date: 2023 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: 8 Transverse_Mercator: Scale_Factor_at_Central_Meridian: 0.999600 Longitude_of_Central_Meridian: -135 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: boundaries Entity_Type_Definition: A boundary, also known as an Area of Interest (AOI) or border, that defines the area covered by the data. Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: boundaries Detailed_Description: Entity_Type: Entity_Type_Label: classified_points Entity_Type_Definition: Classified point cloud data are provided in LASer (LAS) format. Data are classified following ASPRS 2019 guidelines (table 2) and contain return and intensity information. For all ground points, the average point spacing is 54.6 cm, and the average density is 3.35 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, bridge decks, etc. The DSM is a single-band, 32-bit GeoTIFF file of 50-cm resolution. No Data value is set to -9999. Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: dsm Detailed_Description: Entity_Type: Entity_Type_Label: dtm Entity_Type_Definition: The DTM represents bare earth elevations, excluding vegetation, bridge decks, buildings, etc. The DTM is a single-band, 32-bit GeoTIFF file of 50-cm 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: lidar_intensity Entity_Type_Definition: The lidar intensity image describes the relative amplitude of reflected signals contributing to the point cloud. Lidar intensity is (1) primarily a function of scanned object reflectance in relation to the signal frequency, (2) dependent on ambient conditions, and (3) not necessarily consistent between separate scans. The intensity image is a single-band, 16-bit unsigned GeoTIFF file of 50-cm resolution. No Data value is set to 0. Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: lidar_intensity 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 2023-28 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: 20231116 Format_Information_Content: boundaries, classified points, dsm, dtm and lidar intensity Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.14509/31098 Fees: Free download Metadata_Reference_Information: Metadata_Date: 20231116 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