Lidar data for the community of Golovin, Alaska

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Frequently anticipated questions:


What does this data set describe?

Title: Lidar data for the community of Golovin, Alaska
Abstract:
This publication presents lidar data collected over the community of Golovin, on the southern coast of the Seward Peninsula in western Alaska (fig. 1). The original data were collected on November 5, 2013, by Quantum Spatial. The complete, classified lidar dataset was purchased by the State of Alaska Division of Geological & Geophysical Surveys in 2014 in support of coastal vulnerability mapping efforts. For the purposes of open access to lidar datasets in coastal regions of Alaska, this collection is being released as a Raw Data File with an open end-user license. The horizontal datum for this dataset is NAD83 (CORS96), the vertical datum is NAVD88, Geoid 09, and it is projected in UTM Zone 3 North. Units are in Meters. Data have been classified to Ground (class 2) and Default (class 1). Quantum Spatial collected the Golovin LiDAR data on 11/05/2013.
Supplemental_Information:
The DGGS metadata standard extends the FGDC standard to include elements that are required to facilitate our internal data management. These elements, referred to as "layers," group and describe files that have intrinsic logical or topological relationships and correspond to subdirectories within the data distribution package. The metadata layer provides an FGDC metadata file and may include other documentation files. Attribute information for each data layer is described in this metadata file under the "Entity_and_Attribute_Information" section. Data layer contents:
point cloud data - all returns - classified:    Classified (ASPRS standard) LiDAR values for all returns (distributed in LAZ format), data have been classified to Ground (class 2) and Default (class 1).
las-index:    polygons that serve as an index to the spatial location and extent of each point cloud (LAS) bin
border:    polygon that encompasses the maximum geographic extent of the data observations
dsm:	digital surface model (first return), 1 meter resolution, single band raster
dsm_hs:	hillshade of digital surface model (first return), 1 meter resolution, three band raster
dtm:	digital terrain model (bare earth), 1 meter resolution, single band raster
dtm_hs:	hillshade of digital terrain model (first return), 1 meter resolution, three band raster
  1. How should this data set be cited?

    Southerland, L.E., and Kinsman, N.E.M., 2014, Lidar data for the community of Golovin, Alaska: Raw Data File RDF 2014-20, Alaska Division of Geological & Geophysical Surveys, Fairbanks, Alaska, United States.

    Online Links:

    Other_Citation_Details: 23 p.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -163.048528
    East_Bounding_Coordinate: -162.959765
    North_Bounding_Coordinate: 64.557070
    South_Bounding_Coordinate: 64.537851

  3. What does it look like?

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

    Beginning_Date: 05-Nov-2013
    Ending_Date: 2014
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form: report and digital data

  6. How does the data set represent geographic features?

    1. How are geographic features stored in the 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: 3
      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 0.01
      Ordinates (y-coordinates) are specified to the nearest 0.01
      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 1/298.257222101.

      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: NAVD88, derived using GEOID 12A
      Altitude_Resolution: 0.01
      Altitude_Distance_Units: Meters
      Altitude_Encoding_Method:
      Explicit elevation coordinate included with horizontal coordinates

  7. How does the data set describe geographic features?

    point_cloud_data
    point cloud data - all returns - classified: Classified (ASPRS standard) LiDAR values for all returns; File format: LAS 1.1, distributed in LAZ format (Source: Quantum Spatial)

    rdf2014-20-las-index
    polygons that serve as an index to the spatial location and extent of each point cloud (LAS) bin; File format: shapefile (Source: Quantum Spatial)

    NAME
    Bin identification (Source: Quantum Spatial)

    Alpha numeric values that uniquely identify each LAS bin

    rdf2014-20-border
    polygon that encompasses the maximum geographic extent of the data observations; File format: shapefile (Source: Quantum Spatial)

    rdf_2014_20_dsm
    digital surface model (first return), 1 meter resolution, single band raster (Source: Alaska Division of Geological & Geophysical Surveys)

    rdf_2014_20_dsm_hs
    hillshade of digital surface model (first return), 1 meter resolution, three band raster (Source: Alaska Division of Geological & Geophysical Surveys)

    rdf_2014_20_dtm
    digital terrain model (bare earth), 1 meter resolution, single band raster (Source: Alaska Division of Geological & Geophysical Surveys)

    rdf_2014_20_dtm_hs
    hillshade of digital terrain model (first return), 1 meter resolution, three band raster (Source: Alaska Division of Geological & Geophysical Surveys)


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?

    This publication is funded with qualified outer continental shelf oil and gas revenues through the Coastal Impact Assistance Program, U.S. Fish and Wildlife Service, U.S. Department of the Interior. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the opinions or policies of the U.S. Government. Mention of trade names or commercial products does not constitute their endorsement by the U.S. Government.

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

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

    (907)451-5020 (voice)
    dggsgis@alaska.gov

    Hours_of_Service: 8 am to 4:30 pm, Monday through Friday, except State holidays


Why was the data set created?

For the purposes of open access to lidar datasets in coastal regions of Alaska, this collection is being released as a Raw Data File with an open end-user license.


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: 05-Nov-2013 (process 1 of 6)
    Acquisition. Quantum Spatial collected the Golovin lidar data on 11/05/2013. The survey used a Optech Gemini laser system mounted in a Piper Navajo. Data was collected using a single pulse flight plan. Ground level GPS and aircraft IMU were collected during the flight. Optech Gemini Instrument Parameters: Beam diameter: 26 cm, Pulse rate: 70 kHz, Maximum returns: 4, Field of view (FOV): 40 degrees, Beam wavelength: 1064 nm, Frequency of GPS sampling: 2 Hz, Frequency of IMU sampling: 200 Hz, AGL: 800 m, Average pulse density: 4

    Date: 16-Sep-2014 (process 2 of 6)
    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 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 within 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 upon 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 based on known elevation ranges and included the removal of any cycle slips. 7. Using TerraScan and Microstation, ground classifications utilized custom settings appropriate to the study area. 8. The corrected and filtered return points were compared to the RTK ground survey points collected to verify the vertical accuracy. 9. Data were classified to Ground (class 2) and Default (class 1).

    Date: 2014 (process 3 of 6)
    File compression - LAS files were compressed to LAZ format to facilitate online distribution

    Date: 2014 (process 4 of 6)
    Digital Surface Model (DSM) - The digital surface model (first returns) was generated from LAS files in ArcGIS using the LASD to Raster Tool.

    Date: 2014 (process 5 of 6)
    Digital Terrain Model (DTM) - The digital terrain model (bare earth) was generated from LAS files in ArcGIS using the LASD to Raster Tool after filtering to only use ground points.

    Date: 2014 (process 6 of 6)
    Hillshade images were derived from the digital terrain model and digital surface model with Global Mapper and exported as 3 Band GeoTIFFs.

  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?

    Accuracy statements are based on areas of moderate terrain. Diminished accuracies are to be expected in areas of extreme terrain and dense vegetation. The accuracy of each point is expected to meet the vertical accuracy standard, however, derived products may be less accurate in extreme terrain and dense vegetation due to a lesser number of points defining the bare-earth in these areas. Questions regarding data accuracy can be best answered by Quantum Spatial (Anchorage, Alaska) staff.

  2. How accurate are the geographic locations?

    The Optech Gemini system has a stated horizontal accuracy of 1/5500 x altitude. The Golovin lidar data was flown at 800m AGL resulting in a horizontal accuracy of 15 cm.

  3. How accurate are the heights or depths?

    The Root Mean Square Error (RMSE) of the vertical accuracy of this dataset is 0.107 m. Accuracy was assessed using 15 ground survey points. Please see the lidar data report for a discussion of the statistics related to this dataset. The vertical accuracy of the lidar dataset was independently evaluated by DGGS using control points (n=10) that were collected by DGGS during the course of 2012 fieldwork. The standard deviation of the differences between these independent control points and the lidar point-cloud data confirmed the vertical accuracy reported by Quantum Spatial in the 2014 delivery report.

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

    LiDAR data has been collected and processed for all areas within the project study area. AKDGGS's area of interest (AOI) was larger in extent than the previous AOI for which the data was acquired. This resulted in small but unavoidable data gaps along the northern boundary and lower point densities in the eastern section of the AOI not specifically targeted during the acquisition. All discernible laser returns from the fall 2013 acquisition were processed to aid AKDGGS in assessing the topographic and geophysical properties of the study area to support storm monitoring.

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

    Shaded relief images have been visually inspected for data errors such as pits, border artifacts, and shifting. LiDAR flight lines have been examined to ensure consistent elevation values across overlapping flight lines. The Root Mean Square Error (RMSE) of line to line relative accuracy for this dataset is 0.035 m. Please see the LiDAR data report for a discussion of the statistics related to this dataset.


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
    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 2014-20

  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: 12-Dec-2014
Metadata author:
Alaska Division of Geological & Geophysical Surveys
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 Fri Dec 12 16:15:56 2014