Identification_Information: Citation: Citation_Information: Originator: Zechmann, J.M. Originator: Wolken, G.J. Originator: Daanen, R.P. Originator: Wikstrom Jones, K.M. Originator: Herbst, A.M. Publication_Date: 2026 Title: Lidar-derived elevation data for Sitka, Southeast Alaska, collected April 27-29, 2018, and September 27-28, 2019 Geospatial_Data_Presentation_Form: data Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2026-19 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/10.14509/32132 Description: Abstract: Lidar-derived elevation data for Sitka, Southeast Alaska, collected April 27-29, 2018, and September 27-28, 2019, Raw Data File 2026-19, provides aerial lidar derived classified point cloud, digital surface model (DSM), digital terrain model (DTM), and intensity model of Sitka, Southeast Alaska, during leaf-on ground conditions. The survey provides snow-free surface elevations for studying landslide hazards. Ground control data were collected April 27-30, 2018, and aerial lidar data were collected April 27-29, 2018 and September 27-18, 2019, and subsequently processed using a suite of geospatial processing software. These data and accompanying documentation are released as a Raw Data File and are available from the DGGS website at http://doi.org/10.14509/32132. Purpose: The survey provides snow-free surface elevations for studying landslide hazards. This information is essential for assessing hazards, informing risk-mitigation efforts, and supporting decision-making for communities and infrastructure. 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 LAZ format. Data are classified following ASPRS 2025 guidelines and contain return and intensity information. Point cloud elevation information was recorded, processed, and published rounded to the nearest centimeter. For classified ground points, the average density is 6.17 pts/m2, and the average point spacing is 40.3 cm. >dsm: The DSM represents surface elevations, including heights of vegetation, buildings, bridge decks, etc. The DSM is a single-band, 32-bit GeoTIFF file with a 50-cm resolution. No Data value is set to -3.40282306074e+38 (32-bit, floating-point minimum). >dtm: The DTM represents bare earth elevations, excluding vegetation, bridge decks, buildings, etc. The DTM is a single-band, 32-bit float GeoTIFF file with a 50-cm resolution. No Data value is set to -3.40282306074e+38. >footprints: Footprints for tiled data. >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, 32-bit GeoTIFF file of 50-cm resolution. No Data value is set to -3.40282306074e+38. Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 20180427 Ending_Date: 20190927 Currentness_Reference: ground condition Status: Progress: complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -135.424959 East_Bounding_Coordinate: -135.082872 North_Bounding_Coordinate: 57.209405 South_Bounding_Coordinate: 56.980135 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: Coastal Theme_Keyword: Coastal and River Theme_Keyword: Debris Avalanche Theme_Keyword: Debris Flow 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: Landslide Theme_Keyword: Landslide Susceptibility 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: Slope Instability Theme_Keyword: Surface Theme_Keyword: Surficial Theme_Keyword: Surficial Geology Theme_Keyword: Unconsolidated Deposits Place: Place_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Place_Keyword: Arrowhead Peak Place_Keyword: Bear Lake Place_Keyword: Bear Mountain Place_Keyword: Beaver Lake Place_Keyword: Blue Lake Place_Keyword: Cannon Island Place_Keyword: Cascade Creek Place_Keyword: Castle Hill Place_Keyword: Cedar Cove Place_Keyword: Coxe River Place_Keyword: Dog Point Place_Keyword: Entry Point Place_Keyword: Gavan Hill Place_Keyword: Granite Creek Place_Keyword: Green Lake Place_Keyword: Griffith Island Place_Keyword: Guertin Island Place_Keyword: Halibut Point Place_Keyword: Harbor Peak Place_Keyword: Harbor Point Place_Keyword: Harris Island Place_Keyword: Heart Lake Place_Keyword: Indian River Place_Keyword: Indian River Valley Place_Keyword: Japonski Island Place_Keyword: Katlian Bay Place_Keyword: Katlian River Place_Keyword: Lisianski Peninsula Place_Keyword: Lisianski Point Place_Keyword: Marshall Island Place_Keyword: Medvejie Lake Place_Keyword: Mount Edgecumbe Place_Keyword: Sawmill Creek Place_Keyword: Silver Bay Place_Keyword: Sitka Place_Keyword: Sitka Sound Place_Keyword: Swan Lake Place_Keyword: Thimbleberry Lake Place_Keyword: Thomsen Harbor Place_Keyword: Vodopad River Place_Keyword: Watson Point 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 lies within the traditional homelands of the Tlingit peoples. These data products were funded by the State of Alaska and by National Park Service awards #P17AC00903 and #P15AC01879 and collected and processed by DGGS. We thank Coastal Helicopters and 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: Daanen, R.P. Originator: Wolken, G.J. Originator: Herbst, A.M. Publication_Date: 2020 Title: Lidar-derived elevation data for Sitka, Alaska Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2020-13 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/10.14509/30531 Cross_Reference: Citation_Information: Originator: Hubbard, T.D. Originator: Daanen, R.P. Originator: Stevens, D.S.P. Publication_Date: 2025 Title: Debris flow hazard evaluations for multi-hazard risk mapping in Sitka, Alaska Series_Information: Series_Name: Report of Investigation Issue_Identification: RI 2024-2 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 14 p., 6 sheets, scale 1:20,000 Online_Linkage: https://doi.org/10.14509/30187 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Not applicable Logical_Consistency_Report: The data quality is consistent throughout the survey. Completeness_Report: There was no over-collect except for aircraft turns that were eliminated from the dataset. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Horizontal accuracy was not measured for this collection. Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: We measured a mean offset of -79 cm between 156 control points and the point cloud. This offset was reduced to -9 cm by applying a rubber-sheet vertical correction to the lidar point data. We used 39 check points to assess the non-vegetated vertical accuracy of the point cloud ground class using a Triangulated Irregular Network (TIN) approach. The project's vertical accuracy has a root mean square error (RMSE) of 14 cm. We evaluated the relative accuracy for this dataset as the interswath overlap consistency and measured it at 9 cm RMSE. Lineage: Process_Step: Process_Description: Ground survey - Ground control points were collected April 27-30, 2018 (Daanen and others, 2020). We deployed a base Trimble R7 GNSS receiver to provide base station occupation and real-time kinematic (RTK) corrections to points. We surveyed with a rover Trimble R8 GNSS receiver/Trimble Juno 5 Series controller. We collected 234 ground control points and check points, not all of which overlapped with the April 27-29, 2018, and September 27-28, 2019, point cloud. Daanen and others (2020) reported Easting values to 1 decimal place and Northing values to the nearest whole number. Of the 234 ground control points and check points collected in 2018, 195 could be used for calibration and vertical accuracy assessment of the 2018 and 2019 point cloud. Ground control points and check points were collected on bare earth. Process_Date: 20190927 Process_Step: Process_Description: Lidar survey - DGGS used a Riegl VUX1-LR laser scanner integrated with a global navigation satellite system (GNSS) and a Northrop Grumman LN-200C inertial measurement unit (IMU) integrated by Phoenix LiDAR Systems. The sensor can collect a maximum of 820,000 points per second at a range of 215 m, or a minimum of 50,000 points per second at a range of 820 m (ranges assume greater than or equal to 20 percent natural reflectance). The scanner operated with a pulse refresh rate of 100,000-200,000 pulses per second in alpine areas and 400,000-820,000 pulses per second over forested areas, at a scan rate between 20 and 200 revolutions per second. We used a Cessna 180 Skywagon fixed-wing platform and a Bell 206 JetRanger to survey from elevations of 60-400 m above ground level, at a ground speed of ~40 m/s (Cessna 180 Skywagon) or ~30 m/s (Bell 206 JetRanger), and with a scan angle set from 55 to 305 degrees (2018) or 90 to 270 degrees (2019). The total survey area covers ~168 km2. The survey area was accessed by air from Sitka Rocky Gutierrez Airport. Process_Date: 20190430 Process_Step: Process_Description: Dataset processing - We processed point data using 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. IMU and GNSS data were processed 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. For the lidar data collection, the average pulse density is 48.6 pulses/m2, and the average pulse spacing is 14.4 cm. Macros (ordered lists of point classification commands tailored to this dataset) were created in Terrasolid software and used to classify points in accordance with the American Society for Photogrammetry & Remote Sensing (ASPRS) 2025 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. A 50-cm DSM was interpolated from maximum return values from ground, vegetation, bridge deck, and building classes using a binning method. A 50-cm DTM was interpolated from all ground class returns using a binning method and minimum values. We also produced a 1-meter intensity image for the entire area using average binning in ArcGIS Pro, with no normalization or corrections applied. Process_Date: 2025 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: 0.500000 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 LAZ format. Data are classified following ASPRS 2025 guidelines and contain return and intensity information. Point cloud elevation information was recorded, processed, and published rounded to the nearest centimeter. For classified ground points, the average density is 6.17 pts/m2, and the average point spacing is 40.3 cm. 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, bridge decks, etc. The DSM is a single-band, 32-bit GeoTIFF file with a 50-cm 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 represents bare earth elevations, excluding vegetation, bridge decks, buildings, etc. The DTM is a single-band, 32-bit float GeoTIFF file with a 50-cm resolution. No Data value is set to -3.40282306074e+38. Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: dtm Detailed_Description: Entity_Type: Entity_Type_Label: footprints Entity_Type_Definition: Footprints for tiled data. Entity_Type_Definition_Source: DGGS Entity_Attribute_Layer_Name: footprints 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, 32-bit GeoTIFF file of 50-cm resolution. No Data value is set to -3.40282306074e+38. 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 2026-19 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: 20260806 Format_Information_Content: boundaries, classified points, dsm, dtm, footprints and lidar intensity Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.14509/32132 Fees: Free download Metadata_Reference_Information: Metadata_Date: 20260806 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