Identification_Information: Citation: Citation_Information: Originator: Willingham, A.L. Originator: Herriott, T.M. Publication_Date: 2020 Title: Photogrammetry-derived digital surface model and orthoimagery of Slope Mountain, North Slope, Alaska, June 2018 Geospatial_Data_Presentation_Form: imagery Series_Information: Series_Name: Raw Data File Issue_Identification: RDF 2020-1 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 9 p. Online_Linkage: http://doi.org/10.14509/30419 Description: Abstract: The Alaska Division of Geological & Geophysical Surveys (DGGS) conducted a photogrammetric survey of Slope Mountain in northern Alaska. The survey encompasses a well-known outcrop of significance to petroleum resources on the North Slope. Global Navigation Satellite System (GNSS) data and aerial photographs were collected on 20-22 June 2018 and 24 and 26 June 2018, respectively. We processed these data using structure-from-motion (SfM) photogrammetric techniques to create a digital surface model (DSM) and orthorectified aerial optical image (orthoimage). This Raw Data File provides open access to, and an open end-user license for, these data products. All files can be downloaded free of charge from the DGGS website (http://doi.org/10.14509/30419). Purpose: The goal of this data release is to provide a visual and quantitative context for the stratigraphy at Slope Mountain in support of geologic and petroleum systems studies. Slope Mountain is a road-accessible, world-class outcrop of the Cretaceous Nanushuk and Torok Formations, which form oil reservoirs in recent major petroleum discoveries on the North Slope. The Slope Mountain stratigraphy records chiefly progradational sedimentation, with depositional systems extending along depositional strike toward the recent discoveries farther north, providing a valuable outcrop analog to subsurface reservoirs. Within this context, DGGS recently renewed investigations at Slope Mountain, including generation of measured sections and collection of a geochronology sample suite. The DSM and othoimagery yield a three-dimensional framework that complements prior detailed outcrop work and renders geologic and geographic constraints for ongoing and future studies. Supplemental_Information: >digital surface model: A single-band, 32-bit float DSM represents surface elevations of vegetation and uncovered ground surfaces in meters with a GSD of 3.8 cm per pixel. The "No Data" value is set to -32767. The file employs LZ77 compression. >orthoimage: The orthoimage is a three-band, 8-bit unsigned GeoTIFF file. The orthoimagery GSD is 1.9 cm per pixel, and the 'No Data' value is set to 256. Time_Period_of_Content: Time_Period_Information: Single_Date/Time: Calendar_Date: 2018 Currentness_Reference: ground condition Status: Progress: complete Maintenance_and_Update_Frequency: None planned Spatial_Domain: Bounding_Coordinates: West_Bounding_Coordinate: -149.060206 East_Bounding_Coordinate: -149.014684 North_Bounding_Coordinate: 68.734847 South_Bounding_Coordinate: 68.719579 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: Elevation Theme_Keyword: Oil and Gas Theme_Keyword: Orthoimagery Theme_Keyword: Photogrammetry Theme_Keyword: Stratigraphy Theme_Keyword: Structure From Motion Place: Place_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Place_Keyword: North Slope Place_Keyword: Slope Mountain Stratum: Stratum_Keyword_Thesaurus: Alaska Division of Geological & Geophysical Surveys Stratum_Keyword: Nanushuk Formation 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 Data_Set_Credit: The State of Alaska funded this work. We thank helicopter pilot Tom Ratledge (Yukon Aviation) for his adaptability and precise flying during the Slope Mountain photogrammetric survey. Discussions with Katreen Wikstrom Jones and Barrett Salisbury regarding photogrammetry surveys and GNSS data processing are much appreciated. Additional support in data handling and digital products was provided by Andrew Herbst, Mike Hendricks, Kristen Janssen, and Simone Montayne. Cross_Reference: Citation_Information: Originator: Harris, E.E. Originator: Mull, C.G. Originator: Reifenstuhl, R.R. Originator: Montayne, Simone Publication_Date: 2002 Title: Geologic map of the Dalton Highway (Atigun Gorge to Slope Mountain) area, southern Arctic Foothills, Alaska Series_Information: Series_Name: Preliminary Interpretive Report Issue_Identification: PIR 2002-2 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 1 sheet, scale 1:63,360 Online_Linkage: http://doi.org/10.14509/2867 Cross_Reference: Citation_Information: Originator: LePain, D.L. Originator: McCarthy, P.J. Originator: Kirkham, R.A. Publication_Date: 2009 Title: Sedimentology and sequence stratigraphy of the middle Albian-Cenomanian Nanushuk Formation in outcrop, central North Slope, Alaska Series_Information: Series_Name: Report of Investigation Issue_Identification: RI 2009-1 v. 2 Publication_Information: Publication_Place: Fairbanks, Alaska, United States Publisher: Alaska Division of Geological & Geophysical Surveys Other_Citation_Details: 76 p., 1 sheet Online_Linkage: http://doi.org/10.14509/19761 Data_Quality_Information: Attribute_Accuracy: Attribute_Accuracy_Report: The DSM and orthoimagery were visually inspected for data errors such as pits, border artifacts, and shifting. The end-user should be aware that pits and peaks are present in areas of some small water bodies, such as lakes and ponds, and that DSM data are not hydro-flattened in these areas. There are also small artifacts present in some tundra-covered areas. Ragged edges of the survey with many data errors are clipped from both the DSM and orthoimagery. Logical_Consistency_Report: Ground control GNSS data were submitted to the National Geodetic Survey Online Positioning User Service (OPUS) for processing. OPUS generates position solutions based on the National Oceanic and Atmospheric Administration Continuously Operating Reference Station (NOAA CORS) Network. Three of the GNSS points were used as GCPs to calibrate the DSM and orthoimagery; the remaining three points were used as checkpoints in the accuracy assessment of the data products. Completeness_Report: The survey's design ground sample distance (GSD) is 1.8 cm, with a survey area of approximately 2 km2. Forty northeast-southwest-trending, near-nadir-view flight lines were flown with greater than 60% side-lap and 80% end-lap. Two additional cross-cutting near-nadir-view flight lines, as well as six oblique-view flight lines, were also flown. This data release is complete. Positional_Accuracy: Horizontal_Positional_Accuracy: Horizontal_Positional_Accuracy_Report: The three GNSS points designated as checkpoints assess the horizontal accuracy of the data products by comparing their GNSS-derived locations with their position on the orthoimage. The mean offsets (residual) are 0.62 cm in the X-direction and -1.62 cm in the Y-direction, with standard deviations of 32.21 cm (X-direction) and 97.49 cm (Y-direction) and mean absolute errors of 25 cm (X-direction) and 74.36 cm (Y-direction). A horizontal transformation of -1.3685 m in the X-direction and 0.2336 m in the Y-direction is applied. A table of checkpoints and error calculations can be found in the accompanying report. Vertical_Positional_Accuracy: Vertical_Positional_Accuracy_Report: The vertical accuracy of the DSM is evaluated by comparing the elevation values of the same three checkpoints in the photogrammetry-derived DSM to the GNSS-derived elevation values. The mean vertical offset (Z-direction) is -0.75 cm, with a standard deviation of 73.66 cm and the mean absolute error of 55.11 cm. A vertical transformation of 0.5366 m is applied. Lineage: Process_Step: Process_Description: Aircraft and equipment - Aerial photography was conducted from a Bell 206 (Jet Ranger) helicopter at an above ground-level flying height of approximately 145 m. We employed a Nikon D850 digital single-lens reflex camera with a Sigma 35mm f/1.4DG HSM Art lens. The survey's design ground sample distance (GSD) is 1.8 cm, with a survey area of approximately 2 km2. Each photograph is 45.4-megapixels (8256 x 5504 pixels); images were recorded in a 14-bit, losslessly compressed NEF (RAW) file format. Forty northeast-southwest-trending, near-nadir-view flight lines were flown with greater than 60 percent side-lap and 80 percent end-lap. Two additional cross-cutting near-nadir-view flight lines, as well as six oblique-view flight lines, were also flown, further bolstering the photographic dataset and rendering convergent imagery geometries. Select lines were re-flown to fill data gaps, as necessary. The camera was hand-held during the survey, and the shutter was triggered manually based on perceived image overlap and airspeed, resulting in 4,562 total photos. Process_Date: 2018 Process_Step: Process_Description: Georeferencing - Georeferencing described below is based on GNSS data collected on the ground during the photogrammetric campaign, as the camera itself was not fitted with a GNSS receiver. We surveyed ground targets (described below) with a Trimble R7 GNSS receiver, providing both ground control points (GCPs)-to be used in calibration-and checkpoints, which are used in the accuracy assessment of the DSM and orthoimagery. Due to poor satellite coverage in the area of the survey, long occupation times were required to yield appropriate accuracy, which led to fewer GNSS points being collected than is generally preferred. Six GNSS points were collected with the R7 as rapid static (less than 120 minutes) or static (greater than 120 minutes) occupations. Occupation times at GNSS points ranged from 90 to 250 minutes; the longer occupations further ensured adequate position solutions. Each GNSS point was collected at a temporary target placed on the ground surface. At each target site, the GNSS receiver was positioned at the inside corner of two sheets of Tyvek-type material arranged in the shape of an 'L'; the limbs of each target were 100 cm long by 28 cm wide and held down with landscape staples. These targets are easy to locate on the resulting orthoimagery, allowing us to readily reference our GNSS points and check the model for scale discrepancies. Process_Date: 2018 Process_Step: Process_Description: Weather conditions and flight times - Ground targets were deployed and GNSS data were collected between 20 and 22 June 2018. Aerial photographs were collected 24 and 26 June 2018. The first day of the photography survey (24 June 2018) had high, thin overcast conditions that were generally sunny but with variable, lower-level cloud cover, leading to some illumination discrepancies later in the day. The majority of photographs were taken this first day, between 10:55 AM and 3:12 PM. Flight line tracking and photographic coverage were estimated qualitatively by live-monitoring helicopter tracking on a tablet computer relative to planned flight lines. After the 24 June photography survey, we assessed the photographs and flight tracks and identified a few areas that would benefit from additional coverage. To address these potential data gaps, we flew a limited subset of the planned survey again on 26 June 2018, between 10:33 AM and 11:12 AM. The weather on 26 June was high-overcast and sunny, producing somewhat better overall lighting conditions, albeit with deeper shadows, than were encountered during the 24 June photography flight. Process_Date: 2018 Process_Step: Process_Description: Photography - We oversampled the number of frames captured during the photography survey to ensure adequate photographic coverage of the study area. The total number of photographs used to build the model was necessarily reduced in Adobe Photoshop Lightroom to provide approximately 60 percent side-lap and 80 percent end-lap between adjacent flight lines and frames, respectively. The selected NEF format aerial photographs were also optimized in Lightroom to render consistent white balance and exposure parameters and minimize illumination anomalies due to variable lighting conditions during the photogrammetry survey. The selected photographic dataset ultimately comprised 2,611 photographs, which were exported from Lightroom as high-quality JPEG files and then imported into Agisoft Metashape Professional software (Version 1.5.2 build 7838) on a Windows desktop computer. Prior to alignment, image masks were developed as necessary and the photographs were georeferenced using the three GCPs. The photographs were processed in Metashape to edit the sparse point cloud, construct the dense point cloud, calibrate colors, and export the natural color (red, blue, green [RGB]) orthoimagery and DSM GeoTIFF files. Process_Date: 2018 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: 6 Transverse_Mercator: Scale_Factor_at_Central_Meridian: 0.999600 Longitude_of_Central_Meridian: -147 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; EPOCH 2010.00) Altitude_Resolution: 0.019 Altitude_Distance_Units: meters Altitude_Encoding_Method: Explicit elevation coordinate included with horizontal coordinates Entity_and_Attribute_Information: Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: digital surface model Entity_Type_Label: digital surface model Entity_Type_Definition: A single-band, 32-bit float DSM represents surface elevations of vegetation and uncovered ground surfaces in meters with a GSD of 3.8 cm per pixel. The "No Data" value is set to -32767. The file employs LZ77 compression. Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys (DGGS) Detailed_Description: Entity_Type: Entity_Attribute_Layer_Name: orthoimage Entity_Type_Label: orthoimage Entity_Type_Definition: The orthoimage is a three-band, 8-bit unsigned GeoTIFF file. The orthoimagery GSD is 1.9 cm per pixel, and the 'No Data' value is set to 256. Entity_Type_Definition_Source: Alaska Division of Geological & Geophysical Surveys (DGGS) 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 Resource_Description: RDF 2020-1 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: imagery Digital_Transfer_Option: Online_Option: Computer_Contact_Information: Network_Address: Network_Resource_Name: http://doi.org/10.14509/30419 Fees: Free download Metadata_Reference_Information: Metadata_Date: 20200130 Metadata_Contact: Contact_Information: Contact_Organization_Primary: Contact_Person: Simone Montayne 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 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: http://www.dggs.alaska.gov/metadata/dggs.ext Profile_Name: dggs metadata extensions