Elevation point clouds of the north coast of Barter Island, Alaska acquired July 01 2014, September 07 2014, and July 05 2015 (LAZ file)

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Frequently anticipated questions:


What does this data set describe?

Title:
Elevation point clouds of the north coast of Barter Island, Alaska acquired July 01 2014, September 07 2014, and July 05 2015 (LAZ file)
Abstract:
Six elevation point cloud files in LAZ format (compressed LAS binary data) are included in this data release: 3 raw point clouds of unclassified and unedited points and 3 modified point clouds that were spatially shifted and edited to remove outliers and spurious elevation values associated with moving water surfaces. An XYZ coordinate shift was applied to each data set in order to register the data sets to an earth-based datum established from surveyed ground control points. Points are unclassified and ground-reflected color values in the red-green-blue (RGB) schema are included. The horizontal coordinate system is WGS84, UTM Zone 7 North meters; vertical coordinates are relative to the WGS84 ellipsoid. Aerial photographs were collected from a small, fixed-wing aircraft over the coast of Barter Island Alaska on three separate dates: July 01 2014, September 07 2014, and July 05 2015. Precise aircraft position information and structure-from-motion photogrammetric methods were combined to derive high-resolution elevation point clouds.
Supplemental_Information:
Any use of trade, product, or firm names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
  1. How might this data set be cited?
    Nolan, Matt, Snyder, Alexander G., and Gibbs, Ann E., 2019, Elevation point clouds of the north coast of Barter Island, Alaska acquired July 01 2014, September 07 2014, and July 05 2015 (LAZ file): data release DOI:10.5066/P9964TKX, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

    Other_Citation_Details:
    The first Online Linkage link is to the publication landing page. The second link is to the page containing the data.
    This is part of the following larger work.

    Gibbs, Ann E., Nolan, Matt, and Snyder, Alexander G., 2019, Orthophotomosaics, elevation point clouds, digital surface elevation models and supporting data from the north coast of Barter Island, Alaska: data release DOI:10.5066/P9964TKX, U.S. Geological Survey, Pacific Coastal and Marine Science Center, Santa Cruz, CA.

    Online Links:

    Other_Citation_Details:
    Suggested citation: Gibbs, A.E., Nolan, M., and Snyder, A.G., 2019, Orthophotomosaics, elevation point clouds, digital surface elevation models, and supporting data from the north coast of Barter Island, Alaska: U.S. Geological Survey data release, https://doi.org/10.5066/P9964TKX.
  2. What geographic area does the data set cover?
    West_Bounding_Coordinate: -143.790570
    East_Bounding_Coordinate: -143.546318
    North_Bounding_Coordinate: 70.137845
    South_Bounding_Coordinate: 70.115080
  3. What does it look like?
    https://www.sciencebase.gov/catalog/file/get/5bb6a25fe4b0fc368e894766/?name=BTI_LAS_20150705_browse.jpg (JPG)
    Image of a portion of the July 2015 point cloud generated from photogrammetry over Barter Island, Alaska.
  4. Does the data set describe conditions during a particular time period?
    Calendar_Date: 01-Jul-2014
    Currentness_Reference:
    ground condition
  5. What is the general form of this data set?
    Geospatial_Data_Presentation_Form: LAS binary data
  6. How does the data set represent geographic features?
    1. How are geographic features stored in the data set?
      Indirect_Spatial_Reference:
      Point, with variable size and total point count for the 6 files included in the data release as follows: BTI_20140701_raw.laz: 538 MB 94,288,158 points BTI_20140907_raw.laz: 482 MB 80,497,255 points BTI_20150705_raw.laz: 1131 MB 201,277,897 points BTI_20140701_edited.laz: 294 MB 66,467,987 points BTI_20140907_edited.laz: 261 MB 55,454,467 points BTI_20150705_edited.laz: 452 MB 107,893,129 points
    2. What coordinate system is used to represent geographic features?
      The map projection used is Universal Transverse Mercator.
      Projection parameters:
      Scale_Factor_at_Central_Meridian: 0.999600
      Longitude_of_Central_Meridian: -141.00000
      Latitude_of_Projection_Origin: 0.000
      False_Easting: 500000.0000
      False_Northing: 0.0000
      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.001
      Ordinates (y-coordinates) are specified to the nearest 0.001
      Planar coordinates are specified in meters
      The horizontal datum used is WGS_84.
      The ellipsoid used is WGS_84.
      The semi-major axis of the ellipsoid used is 6378137.
      The flattening of the ellipsoid used is 1/298.257224.
      Vertical_Coordinate_System_Definition:
      Altitude_System_Definition:
      Altitude_Datum_Name: WGS_84 Ellipsoid
      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?
    Entity_and_Attribute_Overview:
    The attribute information associated with LAS binary points in the LAZ file is standard, as described in ASPRS (2013). Attributes include location (northing, easting, and elevation in UTM Zone 7 North meters in the WGS84 coordinate systems), color (red, blue, and green components), intensity, and classification. All points are classified as 0 (unclassified). The LAZ file format, a lossless compression for LAS binary data, is described in Isenburg (2013).
    Entity_and_Attribute_Detail_Citation:
    See cross-references for complete citations of ASPRS (2013) and Isenburg (2013).

Who produced the data set?

  1. Who are the originators of the data set? (may include formal authors, digital compilers, and editors)
    • Matt Nolan
    • Alexander G. Snyder
    • Ann E. Gibbs
  2. Who also contributed to the data set?
    U.S. Geological Survey
  3. To whom should users address questions about the data?
    U.S. Geological Survey, Pacific Coastal and Marine Science Center
    Attn: PCMSC Science Data Coordinator
    2885 Mission Street
    Santa Cruz, CA
    USA

    831-427-4747 (voice)
    pcmsc_data@usgs.gov

Why was the data set created?

These points provide the calculated XYZ (horizontal and vertical) coordinates and RGB (red-green-blue) values of the land surface on the north coast of Barter Island Alaska collected on three dates over one calendar year. The data were acquired in order to demonstrate the utility of using structure-from-motion photogrammetric methods for deriving digital elevation data using imagery acquired from a fixed-wing aircraft in remote environments. Companion data sets, including orthophotomosaics and digital surface models are used to evaluate fine-scale morphological and volumetric change to beaches and permafrost bluffs.

How was the data set created?

  1. From what previous works were the data drawn?
    raw point cloud data elevation derived from aerial photography. (source 1 of 1)
    Fodar, Fairbanks, Unpublished, bti_140701.las, bti_140907.las, bti_150705.las.

    Type_of_Source_Media: LAS binary data
    Source_Contribution:
    The raw point cloud data used to produce the edited and geographically shifted point clouds and subsequent digital surface models. See Nolan and others (2015), Gibbs and others (2016), and Gibbs and others (2019) for a more thorough description of the data acquisition methods.
  2. How were the data generated, processed, and modified?
    Date: 2015 (process 1 of 1)
    The elevation point clouds from Fairbanks Fodar (bti_140701.las, bti_140907.las, bti_150705.las) were edited to remove buildings, structures, and spurious elevation values associated with moving water surfaces. Points over the ocean surface and along the shoreline were edited by hand. Points associated with the many small lakes and water bodies on the island were removed using a combination of the raster based Vector Ruggedness Measure (VRM) tool in ArcMap (ESRI; Environmental Systems Research Institute, https://www.arcgis.com/home/item.html?id=9e4210b3ee7b413bbb1f98fb9c5b22d4) and the Lasground_new tool, part of the LAStools suite (Isenburg, 2015). Buildings and small structures were also removed using the LASground_new tool. Each data set was shifted in the x,y and z directions in order to adjust the data from a relative coordinate system to a fixed, ground-based coordinate system as measured at a fixed ground control monument. bti_140701 coordinates were shifted 17 cm north, 7 cm west and 132 cm up in elevation; bti_140907 coordinates were shifted 19 cm south, 13 cm west, and 36 cm up in elevation; bti_150705 coordinates were shifted 12 cm south, 6 cm west, and 32 cm up in elevation. See Gibbs and others (2016) and Gibbs and others (2019) for a more thorough description of the methodology.
  3. What similar or related data should the user be aware of?
    Isenburg, Martin, 2013, LASzip: Lossless compression of LiDAR data: Photogrammetric Engineering & Remote Sensing Vol. 79, No. 2, February 2013, pp. 209-217, American Society for Photogrammetry & Remote Sensing, Bethesda, MD.

    Online Links:

    American Society for Photogrammetry & Remote Sensing (ASPRS), 2013, LAS SPECIFICATION VERSION 1.4 R13: American Society for Photogrammetry & Remote Sensing, Bethesda, MD.

    Online Links:

    Nolan, M., Larsen, C.F., and Sturm, M., 2015, Mapping snow-depth from manned-aircraft on landscape scales at centimeter resolution using Structure-from-Motion photogrammetry: The Cryosphere Vol. 9, pp. 1445-1463.

    Online Links:

    Gibbs, A.E., Nolan, M., and Richmond, B.R., 2016, Evaluating changes to arctic coastal bluffs using repeat aerial photography and structure-from-motion elevation models: Proceedings from 2015 Coastal Sediments Conference CD-ROM; 14 pp.

    Online Links:

    Gibbs, A.E., Nolan, M., Richmond, B.R., Snyder, A.G, and Erikson, L.H., 2019, Assessing patterns of annual change to permafrost bluffs along the North Slope coast of Alaska using high-resolution imagery and elevation models: Geomorphology TBD.

    Online Links:


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

  1. How well have the observations been checked?
    No formal attribute accuracy tests were conducted.
  2. How accurate are the geographic locations?
    No formal horizontal position accuracy assessment was conducted.
  3. How accurate are the heights or depths?
    No formal vertical position accuracy assessment was conducted
  4. Where are the gaps in the data? What is missing?
    Gaps in the point cloud data represent areas where no elevation could be extracted from the imagery during SfM processing (for example and area in shadow) and/or where erroneous points and artifacts were manually removed after SfM processing.
  5. How consistent are the relationships among the observations, including topology?
    Coordinates recorded for each point describe discrete positions in space at the time of capture. No formal logical accuracy tests were conducted on individual points, however, digital surface models derived from the points were compared with GPS-measured locations to determine a relative accuracy of the input data. Elevation values from the ocean and inland water surfaces are not valid because of the inability of the Structure-from-motion (SfM) method to resolve elevations on moving surfaces.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?
Access_Constraints: none
Use_Constraints:
USGS-authored or produced data and information are in the public domain from the U.S. Government and are freely redistributable with proper metadata and source attribution. Please recognize and acknowledge the U.S. Geological Survey as the originator(s) of the dataset and in products derived from these data.
  1. Who distributes the data set? (Distributor 1 of 1)
    U.S. Geological Survey - ScienceBase
    Denver Federal Center, Building 810, Mail Stop 302
    Denver, CO

    1-888-275-8747 (voice)
    sciencebase@usgs.gov
  2. What's the catalog number I need to order this data set? There are 6 LAZ files containing the LAS binary points; 3 raw and unedited point clouds, and 3 edited and shifted point clouds. CSDGM FGDC metadata in XML format is also available for download from the page containing the data.
  3. What legal disclaimers am I supposed to read?
    Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty.
  4. How can I download or order the data?
  5. What hardware or software do I need in order to use the data set?
    These files require software capable of opening binary LAZ files.

Who wrote the metadata?

Dates:
Last modified: 30-Jan-2019
Metadata author:
U.S. Geological Survey, Pacific Coastal and Marine Science Center
Attn: PCMSC Science Data Coordinator
2885 Mission Street
Santa Cruz, CA
United States

831-427-4747 (voice)
pcmsc_data@usgs.gov
Metadata standard:
Content Standard for Digital Geospatial Metadata (FGDC-STD-001-1998)

This page is <https://cmgds.marine.usgs.gov/catalog/pcmsc/alaska/BTI_LASPointCloud_metadata.faq.html>
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