Identification_Information: Citation: 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 Geospatial_Data_Presentation_Form: report, point cloud, GeoTIFF 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 Description: Abstract: The State of Alaska Division of Geological & Geophysical Surveys (DGGS) produced airborne lidar-derived elevation data for Sitka, Alaska. Airborne and ground surveys occurred between the 27th and 30th of April, 2018. These data were produced to assess bare earth slope conditions as part of an overarching, multi-hazard risk analysis for the study area, coordinated through the Federal Emergency Management Agency (FEMA) Cooperating Technical Partners (CTP) program. The project was initiated in response to a tragic debris flow incident that took three Alaskans' lives in 2015. This data collection is 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/10.14509/30531). Purpose: These data were produced to assess bare earth slope conditions as part of an overarching, multi-hazard risk analysis for the study area, coordinated through the Federal Emergency Management Agency (FEMA) Cooperating Technical Partners (CTP) program. The project was initiated in response to a tragic debris flow incident that took three Alaskans' lives in 2015. This data release is one of a series of DGGS publications to present elevation data. Supplemental_Information: >canopy height model: The CHM displays vegetation heights as the difference between DSM and DTM heights. The CHM 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. Note: there are some negative values in the CHM, present in low confidence areas of the DSM and DTM. >classified point cloud data: Classified point cloud data is provided in this collection in compressed .laz format. An average point spacing of 0.15 meters was calculated from all returns and all non-noise classes. >digital surface model: The DSM represents human-observable surface elevations, which include vegetation, buildings, 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 elevations of the ground surface by penetrating or flattening any vegetation, bridges, buildings, etc. 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. Time_Period_of_Content: Time_Period_Information: Range_of_Dates/Times: Beginning_Date: 20180427 Ending_Date: 20180430 Currentness_Reference: ground condition Status: Progress: complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -135.427773 East_Bounding_Coordinate: -135.005119 North_Bounding_Coordinate: 57.209353 South_Bounding_Coordinate: 56.977934 Keywords: Theme: Theme_Keyword_Thesaurus: ISO 19115 Topic Category Theme_Keyword: geoscientificInformation 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: Funding was provided by the State of Alaska and by National Park Service award #P17AC00903 and award #P15AC01879. 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 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Not applicable Logical_Consistency_Report: Relative accuracy for this dataset has been evaluated as the interswath consistency, measured by comparing tie line points within swath overlap areas. The interswath root-mean-square error was calculated to be 0.008 m. Completeness_Report: This data release is complete. Weather was partially cloudy throughout the survey, at times obscuring higher altitude topography in the study area. These conditions limited data coverage to areas below 980 meters elevation. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: Horizontal accuracy was not measured for this collection. Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: One hundred ground control points were used to determine a -0.015 m average offset from the point cloud, which was corrected with a uniform z-transformation of the lidar data. Point cloud accuracy was measured using 95 checkpoints to determine a root-mean-square error of 0.063 m for the project. The accompanying report provides a table of ground control measurements and summary statistics. Lineage: Process_Step: Process_Description: Airborne survey - The lidar survey was conducted with a Riegl VUX1-LR lidar scanner with an integrated GNSS and Northrop Grumman IMU system. The integration was designed by Phoenix LiDAR systems. This survey was flown with a pulse rate between 200,000-400,000 pulses/second and at a scan rate between 80 and 150 revolutions/second. This survey was flown with an average elevation of 400 m above ground level and a ground speed of approximately 40 m/s with a fixed-wing Cessna 185 aircraft. The scan angle was set from 55 to 305 degrees, centered normal to the aircraft's bottom. The accompanying report provides additional detail regarding flight conditions. Process_Date: 20180430 Process_Step: Process_Description: Ground survey - Trimble R8 and R9 RTK GPS systems were used to collect 195 survey points, 100 of which were used as control points and 95 of which were used as checkpoints. Points were gathered by vehicle along the road system and by boat along the coastline. Points were adjusted for accuracy according to OPUS corrections in Trimble Business Center. Process_Date: 20180430 Process_Step: Process_Description: Lidar dataset processing - SDCImport software was used to apply range thresholding, reflectance thresholding, and missed-time-around (MTA) disambiguation for preliminary point cloud noise filtering. In-flight IMU and GNSS data were coupled using Inertial Explorer software to produce the trajectory data. Spatial Explorer software was used to couple the trajectory data with the point cloud. The point cloud data were calibrated using tielines for roll, pitch, and yaw of the aircraft during the survey. This process was first run using all points, then on a per-flightline basis for additional accuracy. Interswath fluctuations in ground points were identified using overlapping tielines to further calibrate the data. The point cloud was classified in accordance with American Society for Photogrammetry and Remote Sensing (ASPRS) guidelines using project-tailored macros. Misclassified points were manually reclassified in post-processing QA/QC. The point cloud was converted from ellipsoidal to orthometric heights using geoid 12B, then uniformly adjusted to maintain a mean offset of 0 with collected ground control. Calibration, classification, and height adjustments were all executed in TerraSolid. Derived products were processed in ArcMap. 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. The CHM was created by subtracting DTM height values from DSM height values. A lidar intensity image was created from first returns of all classes using mean binning. Process_Date: 2019 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: 3 Transverse_Mercator: Scale_Factor_at_Central_Meridian: 0.999600 Longitude_of_Central_Meridian: -165 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: North American Datum of 1983 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: 0.5 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: canopy height model Entity_Type_Definition: The CHM displays vegetation heights as the difference between DSM and DTM heights. The CHM 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. Note: there are some negative values in the CHM, present in low confidence areas of the DSM and DTM. Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys (DGGS) Entity_Attribute_Layer_Name: canopy height model 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. An average point spacing of 0.15 meters was calculated from all returns and all non-noise classes. Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys (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 human-observable surface elevations, which include vegetation, buildings, 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: Alaska Division of Geological & Geophysical Surveys (DGGS) Entity_Attribute_Layer_Name: digital surface model Detailed_Description: Entity_Type: Entity_Type_Label: digital terrain model Entity_Type_Definition: The DTM represents elevations of the ground surface by penetrating or flattening any vegetation, bridges, buildings, etc. 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. Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys (DGGS) Entity_Attribute_Layer_Name: digital terrain model 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 2020-13 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: 20201123 Format_Information_Content: canopy height model, classified point cloud data, digital surface model, and digital terrain model Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.14509/30531 Fees: Free download Metadata_Reference_Information: Metadata_Date: 20201202 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