Identification_Information: Citation: 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 Geospatial_Data_Presentation_Form: report, point cloud, GeoTIFF 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 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 Homer, Alaska. Detailed bare earth elevation data for Homer were collected and processed for use in a landslide hazard resiliency project for the City of Homer. Data coverage includes neighboring Kachemak City. 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 this project on June 19-20, 2019. 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/10.14509/30591). Purpose: Detailed bare earth elevation data for Homer were collected and processed for use in a landslide hazard resiliency project for the City of Homer. Data coverage includes neighboring Kachemak City. This data release is one of a series of DGGS publications to present elevation data. 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. Elevation surfaces interpolated from areas with a point density of fewer than 4 pts/m2 were classified as no data. >digital surface model: DSMs represent surface elevations as they appear to the naked eye. They include 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: DTMs represent 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. >hydro-enforced digital terrain model: The hydro-flattened DTM represents bare earth surfaces which 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 (32-bit, floating-point minimum). Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 20200603 Currentness_Reference: ground condition Status: Progress: complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -151.732364 East_Bounding_Coordinate: -151.373102 North_Bounding_Coordinate: 59.709396 South_Bounding_Coordinate: 59.598820 Keywords: Theme: Theme_Keyword_Thesaurus: ISO 19115 Topic Category Theme_Keyword: geoscientificInformation Theme: Theme_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Theme_Keyword: Digital Elevation Model Theme_Keyword: Digital Surface Model (DSM) Theme_Keyword: Digital Terrain Model Theme_Keyword: Emergency Preparedness Theme_Keyword: Engineering Theme_Keyword: Engineering Geology Theme_Keyword: Geologic Theme_Keyword: Geology Theme_Keyword: Geomorphology Theme_Keyword: Geotechnical Theme_Keyword: Hazards Theme_Keyword: Landslide Theme_Keyword: Landslide Susceptibility Theme_Keyword: LiDAR Theme_Keyword: Point Cloud Data Theme_Keyword: Remote Sensing Theme_Keyword: Surficial Theme_Keyword: Surficial Geology Theme_Keyword: Topography Theme_Keyword: Web Service Place: Place_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Place_Keyword: Bear Canyon Place_Keyword: Beluga Lake Place_Keyword: Bidarki Creek Place_Keyword: Bluff Point Place_Keyword: Bridge Creek Place_Keyword: Carrie Creek Place_Keyword: City of Homer Place_Keyword: City of Kachemak Place_Keyword: Coal Point Place_Keyword: Cook Inlet Place_Keyword: Crossman Ridge Place_Keyword: Diamond Creek Place_Keyword: Diamond Gulch Place_Keyword: Diamond Ridge Place_Keyword: Homer Place_Keyword: Homer Spit Place_Keyword: Kachemak Bay Place_Keyword: Kachemak City Place_Keyword: Lampert Lake Place_Keyword: Mud Bay Place_Keyword: Neilson Canyon Place_Keyword: Palmer Creek Place_Keyword: Twitter Creek Place_Keyword: Waterman Canyon Place_Keyword: Woodard Canyon 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 were collected and processed by the Alaska Division of Geological & Geophysical Surveys staff with funding 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. Cross_Reference: Citation_Information: Originator: Reger, R.D. Publication_Date: 1978 Title: Bluff Point landslide, a massive ancient rock failure near Homer, Alaska Series_Information: Series_Name: Geologic Report Issue_Identification: GR 61B Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: p. 5-9 Online_Linkage: https://doi.org/10.14509/409 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: Suleimani, E.N. Originator: Nicolsky, D.J. Originator: Salisbury, J.B. Publication_Date: 2019 Title: Updated tsunami inundation maps for Homer and Seldovia, Alaska Series_Information: Series_Name: Report of Investigation Issue_Identification: RI 2018-5 v. 2 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 97 p., 11 sheets Online_Linkage: https://doi.org/10.14509/30095 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: Not applicable Logical_Consistency_Report: The relative accuracy for this dataset is 10.38 cm RMSE, calculated as the interswath consistency. Heavy air traffic precluded sufficient scanning of the southwestern portion of Beluga Lake and an area southeast of the Homer Airport runway (along Kachemak Drive). The low-quality data at the southwest end of Beluga Lake has been clipped and flattened to lake level. The tests and processing methods used to ensure data consistency are further described in the accompanying report. Completeness_Report: This dataset is a partial release of the June 3, 2019 lidar project. After the refuel stop, the survey moved across Kachemak Bay to scan the north-facing flank of the Grewingk Glacier valley (the site of a 1967 landslide into the proglacial lake). Data covering the Grewingk Glacier landslide scar will be published separately. However, data quality portrayed here for Homer and Kachemak is consistent throughout the entire 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: The non-vegetated vertical accuracy for classified ground point data is a root mean square error of 3.1 cm. The average pulse spacing is 18.56 cm and the average point density is 29 points per square meter. 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 pulses per second, a scan speed of 200 revolutions per second, at approximately 200 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 98 km2. DGGS collected lidar data on June 3, 2019, initiating the GNSS base station at 08h48 and flying from 10h15 to 15h35 with a 15-minute refuel at 14h15. The sky was clear with light, easterly winds. Heavy air traffic precluded sufficient scanning of the southwestern portion of Beluga Lake and an area southeast of the Homer Airport runway (along Kachemak Drive). Process_Date: 20200603 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. Process_Date: 20200620 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 and manually identified some buildings under dense vegetation, particularly in areas of complex terrain. We hydro-flattened the Bridge Creek Reservoir, Beluga Lake, and Lampert Lake to specified elevations. Lastly, we converted the point cloud from ellipsoidal to orthometric heights using GEOID 12B, then uniformly adjusted the dataset to maintain a mean offset of 0 m with collected ground control. 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. Elevation surfaces interpolated from areas with a point density of fewer than 4 pts/m2 were classified as no data. 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: DSMs represent surface elevations as they appear to the naked eye. They include 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: 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: DTMs represent 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. Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys (DGGS) Entity_Attribute_Layer_Name: digital terrain model Detailed_Description: Entity_Type: Entity_Type_Label: hydro-enforced digital terrain model Entity_Type_Definition: The hydro-flattened DTM represents bare earth surfaces which 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: Alaska Division of Geological & Geophysical Surveys (DGGS) Entity_Attribute_Layer_Name: hydro-enforced 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 (32-bit, floating-point minimum). Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys (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 2021-2 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: report point-cloud GeoTIFF Format_Version_Date: 20210126 Format_Information_Content: classified point cloud data, digital surface model, digital terrain model, hydro-enforced digital terrain model, and lidar intensity image Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: https://doi.org/10.14509/30591 Fees: Free download Metadata_Reference_Information: Metadata_Date: 20210127 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