Lidar-derived elevation data for the Utqiagvik-Atqasuk region, Alaska, collected August 2019

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Frequently anticipated questions:


What does this data set describe?

Title:
Lidar-derived elevation data for the Utqiagvik-Atqasuk region, Alaska, collected August 2019
Abstract:
Lidar-derived elevation data for the Utqiagvik-Atqasuk region, Alaska, collected August 2019, Raw Data File 2022-10, provides classified point cloud, digital terrain model (DTM), surface model (DSM), and intensity model data for the communities of Utqiagvik and Atqasuk and surrounding areas. The data were collected in support of the Alaska Strategic Transportation and Resources (ASTAR) program for the purpose of investigating the potential for future road infrastructure connecting the communities. Aerial lidar data were collected between August 19 and 23, 2019, and subsequently processed using a suite of geospatial processing software. These products are released as a Raw Data File with an open end-user license. All files can be downloaded from the Alaska Division of Geological & Geophysical Surveys website (http://doi.org/10.14509/30870).
Supplemental_Information:
classified points:    Classified point cloud data are provided in this collection in compressed LAZ format. Data are classified in accordance with ASPRS 2014 guidelines and contain return and intensity information. The average ground point spacing was 34 cm and the average density was 8.51 pts/m^2	
digital surface model:    The DSM represents surface elevations including heights of vegetation, buildings, bridges, and other structures. The DSM is a single band, 32-bit GeoTIFF file, with a ground sample distance of 1 meter. No Data value is set to -3.40282306074e+038.	
digital terrain model:    The DTM represents surface elevations of ground surfaces, excluding vegetation, bridges, buildings, etc. The DTM is a single-band, 32-bit float GeoTIFF file, with a ground sample distance of 1 meter. 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 1 meter. No Data value is set to  3.40282306074e+038 (32-bit, floating-point minimum).
  1. How might this data set be cited?
    Herbst, A.M., and Daanen, R.P., 2022, Lidar-derived elevation data for the Utqiagvik-Atqasuk region, Alaska, collected August 2019: Raw Data File RDF 2022-10, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 8 p.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -157.734935
    East_Bounding_Coordinate: -156.215074
    North_Bounding_Coordinate: 71.355669
    South_Bounding_Coordinate: 70.466536
  3. What does it look like?
  4. Does the data set describe conditions during a particular time period?
    Beginning_Date: 19-Sep-2019
    Ending_Date: 23-Sep-2019
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      This is a raster data set.
    2. What coordinate system is used to represent geographic features?
      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      UTM_Zone_Number: 4
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -159
      Latitude_of_Projection_Origin: 0
      False_Easting: 500000.000000
      False_Northing: 0
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest .00000001
      Ordinates (y-coordinates) are specified to the nearest .00000001
      Planar coordinates are specified in Meters
      The horizontal datum used is NAD83 (2011).
      The ellipsoid used is GRS 80.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257222101.
      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
  7. How does the data set describe geographic features?
    classified points
    Classified point cloud data are provided in this collection in compressed LAZ format. Data are classified in accordance with ASPRS 2014 guidelines and contain return and intensity information. The average ground point spacing was 34 cm and the average density was 8.51 pts/m^2 (Source: DGGS)
    digital surface model
    The DSM represents surface elevations including heights of vegetation, buildings, bridges, and other structures. The DSM is a single band, 32-bit GeoTIFF file, with a ground sample distance of 1 meter. No Data value is set to -3.40282306074e+038. (Source: DGGS)
    digital terrain model
    The DTM represents surface elevations of ground surfaces, excluding vegetation, bridges, buildings, etc. The DTM is a single-band, 32-bit float GeoTIFF file, with a ground sample distance of 1 meter. No Data value is set to -3.40282306074e+038. (Source: DGGS)
    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 1 meter. No Data value is set to 3.40282306074e+038 (32-bit, floating-point minimum). (Source: DGGS)

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
  2. Who also contributed to the data set?
    These data products were funded by the U.S. Bureau of Land Management and the State of Alaska's Arctic Strategic Transportation and Resources (ASTAR) project. We thank Clearwater Air, Inc., for their professional and expert flight services.
  3. To whom should users address questions about the data?
    Alaska Division of Geological & Geophysical Surveys
    Metadata Manager
    3354 College Road
    Fairbanks, AK
    USA

    (907)451-5020 (voice)
    (907)451-5050 (FAX)
    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.

Why was the data set created?

The data were collected in support of the Alaska Strategic Transportation and Resources (ASTAR) program for the purpose of investigating the potential for future road infrastructure connecting the communities.

How was the data set created?

  1. From what previous works were the data drawn?
  2. How were the data generated, processed, and modified?
    Date: 23-Sep-2019 (process 1 of 3)
    Aerial photogrammetric survey - DGGS used a Riegl VUX1-LR laser scanner integrated with a global navigation satellite system (GNSS) and Northrop Grumman LN-200C inertial measurement unit (IMU). The lidar integration system was designed by Phoenix LiDAR Systems. The sensor can collect up to 820,000 points per second over a distance of 150 m. This survey was flown with a pulse refresh rate of 400,000 pulses per second, at a scan rate between 80 and 220 lines per second. This survey was flown with an average elevation of 200 m above ground level and a ground speed of approximately 30 m/s with a fixed-wing configuration, using a Cessna 180. The scan angle was set from 80 to 280 degrees. The total area surveyed was approximately 1,595 km^2. Aerial lidar was collected between August 19 and 23, 2019. Seven flightlines collected on the evening of August 22 yielded too large a file for our software to process and the points from those lines are not represented in our final product.
    Date: Sep-2018 (process 2 of 3)
    Ground survey - Ground survey points from an UMIAQ, LLC, collection in September 2018, were used as control and checkpoint data for this dataset. These survey data were originally gathered in support of a USGS 3DEP funded lidar project, headed by Quantum Spatial (now NV5 Geospatial).
    Date: 2022 (process 3 of 3)
    Photogrammetric dataset processing - Point data were processed in SDCimport software for initial filtering and multiple-time-around (MTA) disambiguation. MTA errors, corrected in this process, are the result of imprecise interpretations of received pulse time intervals and occur more frequently with higher pulse refresh rates. Inertial Measurement Unit (IMU) and Global Navigation Satellite System (GNSS) data were processed in Inertial Explorer and used to integrate flightline information with the point cloud in Spatial Explorer software. The point data were calibrated at an incrementally precise scale of sensor movement and behavior, incorporating sensor velocity, roll, pitch, and yaw fluctuations throughout the survey. Points were classified in accordance with American Society for Photogrammetry and Remote Sensing (ASPRS) 2014 guidelines, using macros designed in Terrasolid software. Once classified, points underwent a geometric transformation and were converted from ellipsoidal heights to GEOID12B (Alaska) orthometric heights. Raster products were derived from the point cloud using ArcGIS Pro. The DTM was interpolated from all ground class returns using a TIN-based method. The DSM was likewise interpolated from only the first return points. An intensity image was also produced in ArcGIS Pro, using closest-to-mean binning.
  3. What similar or related data should the user be aware of?
    Buzard, R.M., Heiner, Daniel, Overbeck, J.R., and Glenn, R.J.T., 2021, Photogrammetry-derived orthoimagery and elevation for Wainwright, Alaska, collected August 3, 2021: Raw Data File RDF 2021-18, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 4 p
    Gavel, M.M., and Hubbard, T.D., 2021, Digital data addendum: Analytical data and field observations from surficial geology and morphology of the Alaskan central Arctic Coastal Plain, 1981-1987: Report of Investigation RI 93-1A, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 6 p

How reliable are the data; what problems remain in the data set?

  1. How well have the observations been checked?
    Not applicable
  2. How accurate are the geographic locations?
    Horizontal accuracy was not measured for this collection.
  3. How accurate are the heights or depths?
    A mean offset of -25.5 cm was measured between 19 control points and point cloud ground returns. This offset was reduced to 0.001 cm by performing a vertical transformation of the lidar point data. Thirty-three check points were used to determine the non-vegetated vertical accuracy (NVA) of the point cloud ground class, using a TIN-based approach. Project NVA was calculated to have a root mean square error (RMSE) of 5.2 cm. Relative accuracy for this dataset was evaluated as the interswath overlap consistency and was measured at 0.95 cm RMSE. See the accompanying report for check points and additional detail.
  4. Where are the gaps in the data? What is missing?
    This is a partial data release and contains all data collected except from the seven flightlines shown in figure 1 of the accompanying report. There is no over collect. The data quality is consistent throughout the survey.
  5. How consistent are the relationships among the observations, including topology?
    DGGS visually inspected the orthoimage for data errors such as shifts, seamline mismatches, and water noise overlapping land. There were no significantly erroneous areas that required repair.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
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.
  1. Who distributes the data set? (Distributor 1 of 1)
    Alaska Division of Geological & Geophysical Surveys
    Metadata Manager
    3354 College Road
    Fairbanks, AK
    USA

    (907)451-5020 (voice)
    (907)451-5050 (FAX)
    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.
  2. What's the catalog number I need to order this data set? RDF 2022-10
  3. What legal disclaimers am I supposed to read?
    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.
  4. How can I download or order the data?

Who wrote the metadata?

Dates:
Last modified: 11-Aug-2022
Metadata author:
Alaska Division of Geological & Geophysical Surveys
Attn: Simone Montayne
Metadata Manager
3354 College Road
Fairbanks, AK
USA

(907)451-5020 (voice)
(907)451-5050 (FAX)
dggspubs@alaska.gov
Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays
Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:

Generated by mp version 2.9.50 on Thu Aug 11 13:46:54 2022