LiDAR Datasets of Alaska

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Frequently anticipated questions:


What does this data set describe?

Title: LiDAR Datasets of Alaska
Abstract:
This interactive map was designed to display public-domain LiDAR datasets of Alaska. Data types available include: hillshade; intensity images; and shaded relief. The map offers zoom and scroll options, and multiple base map layers. We provide an easy point and click interface to show data originators and, when available, a link to download the data. Users are also able to bookmark and share areas of interest. The initial launch is limited to data acquired to date by DGGS. However, DGGS is actively developing a comprehensive repository of Alaska's public-domain LiDAR data. The application will be periodically updated to incorporate our complete collection.
Supplemental_Information:
This FGDC compliant metadata file describes an interactive map interface.
  1. How should this data set be cited?

    DGGS Staff, 2013, LiDAR Datasets of Alaska: Digital Data Series DDS 4, Alaska Division of Geological & Geophysical Surveys, Fairbanks, AK, USA.

    Online Links:

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: 167
    East_Bounding_Coordinate: -129
    North_Bounding_Coordinate: 72
    South_Bounding_Coordinate: 46

  3. What does it look like?

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

    Calendar_Date: 2013
    Currentness_Reference: ground condition

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

    Geospatial_Data_Presentation_Form: map

  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?

      The map projection used is GS_1984_Web_Mercator_Auxiliary_Sphere.

      Projection parameters:
      Standard_Parallel: 0
      Longitude_of_Central_Meridian: 0
      False_Easting: 0
      False_Northing: 0

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.00000001
      Ordinates (y-coordinates) are specified to the nearest 0.00000001
      Planar coordinates are specified in meters

      The horizontal datum used is D_WGS_1984.
      The ellipsoid used is WGS_1984.
      The semi-major axis of the ellipsoid used is 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257223563.

  7. How does the data set describe geographic features?

    Base Layer
    Map base layers which allow users to select street, terrain, or satellite views of the surrounding data. The base layers provided by the application may be changed if improved options become available. Base layers were selected by DGGS staff and data sources are listed on the application. (Source: See map)

    Overlays
    USGS quadrangle boundaries and LiDAR hillshade, shaded relief, and intensity images. (Source: Alaska Division of Geological & Geophysical Surveys)

    Web Map Service
    the LiDAR images served by this application are also provided as a Web Map Service (WMS), the URLs are available on the application citation page. (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 work was supported by the State of Alaska's General Fund.

  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?

In support of geologic mapping and hazards evaluation the Alaska Division of Geological & Geophysical Surveys (DGGS) is acquiring and compiling public-domain LiDAR datasets throughout Alaska. We have compiled an interactive map to provide the public with an accurate, user-friendly, reference-based inventory of this data. This resource is intended to facilitate planning and research by providing simple and quick means of visualizing structure locations and characteristics. Users must recognize original collection resolution limitations when zooming in farther than the mapped resolution for a given dataset and treat resulting visual representations with appropriate caveats.


How was the data set created?

  1. From what previous works were the data drawn?

    DGGS Publications Catalog (source 1 of 1)
    Alaska Division of Geological & Geophysical Surveys, 2013, Alaska Division of Geological & Geophysical Surveys Publications Catalog.

    Online Links:

    Type_of_Source_Media: online
    Source_Contribution: provides citation information for the LiDAR data sources

  2. How were the data generated, processed, and modified?

    Date: 2013 (process 1 of 4)
    map-based search interface - We built a interactive web map using ArcGIS for Server, javascript, and OpenLayers.

    Date: 2013 (process 2 of 4)
    base layer selection - We examined publicly available map base layers that were available at the time of publication and selected those which provided the best overall level of reliability, accuracy, and visual appeal. The base layers provided by the application may be changed if improved options become available.

    Date: 2013 (process 3 of 4)
    LiDAR data acquisition - DGGS is engaged in an ongoing effort to provide references to public domain LiDAR data that has been collected throughout Alaska. Our publications catalog provides direct links to data purchased by DGGS and data source contact information for data that we have acquired from other agencies.

    Data sources used in this process:

    • DGGS Publications Catalog

    Date: 2013 (process 4 of 4)
    LiDAR image generation - The processes used to generate the intensity, shaded relief, and hillshade images will vary according to the originating data. In some locations the LiDAR layers will be derived from comprehensively reviewed LiDAR images, in other cases we may process the classified point cloud data in house to provide an "as is" product. If areas of overlapping data occur we will preferentially display the the higher quality image. Users should refer to the originating source to learn more about the data quality of a given area.

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

    Alaska Division of Geological & Geophysical Surveys, 2013, Alaska Division of Geological & Geophysical Surveys Publications Catalog - keyword: Lidar.

    Online Links:


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

  1. How well have the observations been checked?

    For the purpose of creating an FGDC (CSDGM) compliant metadata file, we consider the attributes of this application to be the underlying base layer maps and data layers. The relative accuracy of the base layers is entirely determined by the data provider and varies by location and scale. The base layer options may change over time as new or better sources become available. The relative accuracy of the LiDAR data varies by source and is dependent on how it was collected and processed. The intended purpose of this application is to provide a preview of the available datasets. For rigorous scientific use users should obtain the originating data from the cited source.

  2. How accurate are the geographic locations?

    The data shown in the interactive web map has been reprojected from its native projection into WGS 1984 Web Mercator Auxiliary Sphere (WKID: 3857; Authority: EPSG) for display in a web browser. For information regarding the native projection of the source data, please refer to the metadata supplied with any data downloaded from the interface. Disclaimer: While digital data can be displayed precisely at any scale, data accuracy remains constant. Although the user may increase the displayed scale, uncertainties and errors in raster location remain tied to original collection resolution. Users must recognize these limitations when zooming in farther than the mapped resolution for a given dataset and treat resulting visual representations with appropriate caveats.

  3. How accurate are the heights or depths?

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

    The attributes displayed by this application were compiled from various public-domain base layers and LiDAR datasets. This tool is not an exhaustive library of all the LiDAR that has been collected throughout Alaska. The LiDAR datasets served by this application were either published by DGGS or other governmental agency or submitted to DGGS with explicit distribution permission.

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

    We have used informal "hallway testing" to ensure that the interface functions according to project specifications. The interface and underlying programming may change in response to user feedback.


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?

    DDS 4

  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: 09-Oct-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 Thu Oct 9 12:19:19 2014