High-resolution lidar data for infrastructure corridors, Sagavanirktok Quadrangle, Alaska

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Frequently anticipated questions:


What does this data set describe?

Title:
High-resolution lidar data for infrastructure corridors, Sagavanirktok Quadrangle, Alaska
Abstract:
In advance of design, permitting, and construction of a pipeline to deliver North Slope natural gas to out-of-state customers and Alaska communities, the Division of Geological & Geophysical Surveys (DGGS) has acquired lidar (light detection and ranging) data along proposed pipeline routes, nearby areas of infrastructure, and regions where significant geologic hazards have been identified. Lidar data will serve multiple purposes, but have primarily been collected to (1) evaluate active faulting, slope instability, thaw settlement, erosion, and other engineering constraints along proposed pipeline routes, and (2) provide a base layer for the state-federal GIS database that will be used to evaluate permit applications and construction plans. Lake polygons represent areas of water bodies (excluding streams and rivers) > 150 square meteres, present at the time of lidar data collection.
Supplemental_Information:
This metadata file was written to document and describe, as a whole, all the lake polygon files generated for this project. The original metadata files provided by Watershed Sciences, Inc. are also included in the download package and may provide additional useful information that is specific to each file. The metadata files provided by Watershed Sciences, Inc. have not been reviewed for accuracy or compliance with FGDC standards. The DGGS metadata standard extends the FGDC standard to include several elements that are required to facilitate internal data management. For each data delivery area, reports documenting data collection methodology, accuracy, and quality control were provided by Watershed Sciences and the Oregon Department of Geology and Mineral Industries (DOGAMI). These reports have been combined into single comprehensive reports organized by delivery region. The lidar QC report (the comprehensive report from DOGAMI) and the lidar delivery report (the comprehensive report from Watershed Sciences) can be found at <http://www.dggs.alaska.gov/pubs/id/22722>. Information about the quadrangles included in individual delivery regions can be found in the lidar delivery index report included with the data download. The DGGS metadata standard extends the FGDC standard to include several elements that are required to facilitate internal data management. This dataset is described as a single layer titled:
lakes	Polygons showing lakes greater than 150 square meters
  1. How should this data set be cited?

    Hubbard, T.D., Braun, M.L., Westbrook, R.E., and Gallagher, P.E., 2011, High-resolution lidar data for infrastructure corridors, Sagavanirktok Quadrangle, Alaska: Raw Data File RDF 2011-3T, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, Alaska USA.

    Online Links:

    This is part of the following larger work.

    Hubbard, T.D., Koehler, R.D., and Combellick, R.A., 2011, High-resolution lidar data for Alaska infrastructure corridors: Raw Data File RDF 2011-3, State of Alaska, Department of Natural Resources, Division of Geological & Geophysical Surveys, Fairbanks, AK USA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -150
    East_Bounding_Coordinate: -147
    North_Bounding_Coordinate: 70
    South_Bounding_Coordinate: 69

  3. What does it look like?

  4. Does the data set describe conditions during a particular time period?

    Beginning_Date: 2010
    Ending_Date: 2011
    Currentness_Reference: ground condition

  5. What is the general form of this data set?

    Geospatial_Data_Presentation_Form: vector digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the data set?

      This is a Vector data set.

    2. What coordinate system is used to represent geographic features?

      Grid_Coordinate_System_Name: Universal Transverse Mercator
      Universal_Transverse_Mercator:
      Transverse_Mercator:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -147
      Latitude_of_Projection_Origin: 0.000000
      False_Easting: 500000.000000
      False_Northing: 0.000000
      UTM_Zone_Number: 6

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 1.000000
      Ordinates (y-coordinates) are specified to the nearest 1.000000
      Planar coordinates are specified in meters

      The horizontal datum used is North American Datum of 1983.
      The ellipsoid used is Geodetic Reference System 80.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257222.

  7. How does the data set describe geographic features?

    lakes.shp
    Polygons showing lakes greater than 150 square meters (Source: Watershed Sciences)


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?

    Data collection was supported by funding from the Department of Natural Resources (DNR), Division of Geological & Geophysical Surveys (DGGS), the Alaska Gas Pipeline Project Office, the Office of the Federal Coordinator, and the Alaska Gasline Development Corporation (AGDC). Lidar data were collected and processed by Watershed Sciences of Corvalis, Oregon. Survey data were collected by McClintock Land Associates of Eagle River, AK. Lidar data and derivative products were checked for quality, completeness, and accuracy by State of Oregon Department of Geology & Mineral Industries based in Portland, OR.

  3. To whom should users address questions about the data?

    Alaska Division of Geological &amp; Geophysical Surveys
    GIS Analyst
    3354 College Road
    Fairbanks, AK 99709-3707
    USA

    (907)451-5029 (voice)


Why was the data set created?

Provide vector data depicting water bodies greater than 150 square meters.


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: 2010 (process 1 of 3)
    Acquisition: The lidar data were collected between September and October 2010 and between May and July 2011. The survey used the Leica ALS 60 system. Near-nadir scan angles were used to increase penetration of vegetation to ground surfaces. Ground-level GPS and aircraft IMU were collected during the flight.

    Date: 2010 (process 2 of 3)
    Processing lidar data: (1) Flight lines and data were reviewed to ensure complete coverage of the study area and positional accuracy of the laser points. (2) Laser point-return coordinates were computed using ALS Post Processor software, IPAS Pro GPS/INS software, and Waypoint GPS, based on independent data from the lidar system, IMU, and aircraft. (3) The raw lidar file was assembled into flight lines per return with each point having an associated x, y, and z coordinate. (4) Visual inspection of swath-to-swath laser point consistencies in the study area were used to perform manual refinements of system alignment. (5) Custom algorithms were designed to evaluate points between adjacent flight lines. Automated system alignment was computed based on randomly selected swath-to-swath accuracy measurements that consider elevation, slope, and intensities. Specifically, refinement in the combination of system pitch, roll, and yaw-offset parameters optimize internal consistency. (6) Noise (e.g., pits and birds) was filtered using ALS postprocessing software, based on known elevation ranges, and included the removal of any cycle slips.

    Date: 2010 (process 3 of 3)
    Hydro-flattening: A combination of automated and manual detection and adjustment techniques was used to identify lake boundaries and water levels for closed water bodies with a surface area > 150 square meters.

  3. What similar or related data should the user be aware of?


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

  1. How well have the observations been checked?

    The accuracy of the lake polygons depends on the horizontal and vertical positional accuracy of the lidar data, the accuracy of the laser return classification and the accuracy of the hydro-flattening process. Refer to the lidar delivery report and lidar QC report for more details on the accuracy of the lidar data for each delivery area, including a comparison of GCP elevations with bare-earth DEM elevations. More information on the hydro-flattening process can also be found in the lidar delivery report.

  2. How accurate are the geographic locations?

    Accuracies of lake boundaries is uncertain and variable depending on the accuracy of the lidar return classification and algorithms used for lake-edge detection, but is believed to be within a few meters.

  3. How accurate are the heights or depths?

  4. Where are the gaps in the data? What is missing?

    Polygons were created for all lakes with an area greater than 150 square meters. Rivers and streams were excluded from the data set.

  5. How consistent are the relationships among the observations, including topology?

    The following logical consistency tests were performed. 1) All lake polygons were checked to ensure that lidar data within the polygons was classified as water. 2) All lake edge lines were manually reviewed and edited in a 3-D environment by the contractor.


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 &amp; 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
    3354 College Road
    Fairbanks, AK 99709-3707
    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 (<http://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 2011-3T

  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?

  5. Is there some other way to get the data?

    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 over the counter, by mail, phone, fax, or email from the DGGS Fairbanks office. 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 exact shipping amount.


Who wrote the metadata?

Dates:
Last modified: 20-Aug-2013
Metadata author:
Metadata manager
3354 College Road
Fairbanks, AK 99709-3707
USA

(907)451-5020 (voice)

Metadata standard:
FGDC Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:


Generated by mp version 2.9.21 on Tue Aug 20 16:54:06 2013