Spatial Data Management System Line Layer, Surveyed Lines, Alaska

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Frequently anticipated questions:

What does this data set describe?

Spatial Data Management System Line Layer, Surveyed Lines, Alaska
This dataset is a spatial representation of the Public Land Survey System (PLSS) in Alaska, generated from land survey records. The data represents a seamless spatial portrayal of land parcels, their legal descriptions, corner positioning and markings, and survey measurements. This data is intended for mapping purposes only and is not a substitute or replacement for the legal land survey records or other legal documents.
Measurement and attribute data are collected from survey records using data entry screens into a relational database. The database design is based upon the FGDC Cadastral Content Data Standard. Corner positions are derived by geodetic calculations using measurement records. Closure and edgematching are applied to produce a seamless dataset. The resultant features do not preserve the original geometry of survey measurements, but the record measurements are reported as attributes. Additional boundary data are derived by spatial capture, protraction and GIS processing. The spatial features are stored and managed within the relational database, with active links to the represented measurement and attribute data.
  1. How should this data set be cited?

    Alaska State Office, Bureau of Land Management, Unpublished Material, Spatial Data Management System Line Layer, Surveyed Lines, Alaska.

  2. What geographic area does the data set cover?

    West_Bounding_Coordinate: -172.143382
    East_Bounding_Coordinate: -119.427022
    North_Bounding_Coordinate: 71.376236
    South_Bounding_Coordinate: 54.560274

  3. What does it look like?

    d:browse_graphicsdms_lines.gif (GIF)
    Surveyed Lines in SDMS

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

    Calendar_Date: 2002
    Currentness_Reference: publication date

  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. It contains the following vector data types (SDTS terminology):

      • String (27608)

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

      The map projection used is Albers Conical Equal Area.

      Projection parameters:
      Standard_Parallel: 55.000000
      Standard_Parallel: 65.000000
      Longitude_of_Central_Meridian: -154.000000
      Latitude_of_Projection_Origin: 50.000000
      False_Easting: 0.000000
      False_Northing: 0.000000

      Planar coordinates are encoded using coordinate pair
      Abscissae (x-coordinates) are specified to the nearest 0.001723
      Ordinates (y-coordinates) are specified to the nearest 0.001723
      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 6378137.000000.
      The flattening of the ellipsoid used is 1/298.257222.

  7. How does the data set describe geographic features?

    Database:Owner:Layer (Source: SDMS Database)

    System generated number - used to join attributes to Informix Line Table (Source: SDMS Database)

    Range of values

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?

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

    John Sroufe
    Branch of Spatial Records
    Chief, Branch of Spatial Records
    222 W. 7th Ave #13
    Anchorage, AK 99513

    907-271-5481 (voice)
    907-271-4549 (FAX)

    Hours_of_Service: 0800 - 1630

Why was the data set created?

This dataset was created to provide an accurate, seamless portrayal of the PLSS network, based upon survey records. The dataset is intended for use as a base layer for mapping purposes, and as a framework for the portrayal of land ownership

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: Not complete (process 1 of 2)
    ArcInfo Processing: The data exported from database via an XML file is parsed and used to create ArcInfo point and line generate files.
    A line coverage is created from the appropriate generate file and the points added using ArcEdit. Topology is built and the resulting coverage is projected to Alaska Albers.
    If interesections are detected during the build, the source data is examined to determine if errors exist in the coordinate data exported from the SDMS database. Standard processing procedures require a build rather than clean to create topology.

    Person who carried out this activity:

    Tim Varner
    Branch of Spatial Records
    Spatial Database Administrator
    222 W 7th Ave #13
    Anchorage, AK 99513

    (907) 271-5799 (voice)
    (907) 271-4549 (FAX)

    Hours_of_Service: 0800 - 1630
    Date: Not complete (process 2 of 2)
    ArcSDE Processing: Coverages are loaded into an ArcSDE Feature Dataset using the cov2sde utility with the append option.

    Person who carried out this activity:

    Tim Varner
    Branch of Spatial Records
    Spatial Database Administrator
    222 W 7th Ave #13
    Anchorage, AK 99513

    (907) 271-5799 (voice)
    (907) 271-4549 (FAX)

  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 id of the line is the only non-system generated attibute in the data set. This attribute correlates directly with the tabular data used to construct the line boundary.

  2. How accurate are the geographic locations?

  3. How accurate are the heights or depths?

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

    Data collection is complete as of the date of collection. This metadata describes a snapshot of the data current as of the date of publication.

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

    Arc-node topology exists
    All survey lines are based on either known or derived corners (points) determined through geodetic calculations. Boundaries are constructed from corners and polygons are built from the resulting lines.

How can someone get a copy of the data set?

Are there legal restrictions on access or use of the data?

Discretionary, contains no sensitive information - generally considered releaseable.
Accuracy published on or derived from BLM's official survey records. Please refer to BLM's official survey records for specific bearing and distance information.
Any hardcopies or published datasets using these data shall clearly indicate their source. Any users wishing to modify the data are obligated to describe the types of modifications they have performed. User specifically agrees not to misrepresent the data, nor to imply that changes made were approved or endorsed by the BLM. Any discrepancies or errors in this data should be reported to

  1. Who distributes the data set? (Distributor 1 of 1)

    John Montgomery
    Alaska State Office, Bureau of Land Management
    State Records Administrator
    222 W. 7th Ave #13
    Anchorage, AK 99513

    (907) 271-5054 (voice)
    (907) 271-4549 (FAX)

    Hours_of_Service: 0800 -1630
  2. What's the catalog number I need to order this data set?

  3. What legal disclaimers am I supposed to read?

    No warranty is made by the Bureau of Land Management as to the accuracy, reliability, or completeness of these data for individual use or aggregate use with other data.

  4. How can I download or order the data?

Who wrote the metadata?

Last modified: 27-Feb-2002
Last Reviewed: 2003
Metadata author:
Tim Varner
Branch of Spatial Records
Spatial Database Administrator
222 W 7th Ave #13
Anchorage, AK 99513

(907) 271-5799 (voice)
(907) 271-4549 (FAX)

Hours_of_Service: 0800 - 1630
Metadata standard:
FGDC Content Standards for Digital Geospatial Metadata (FGDC-STD-001-1998)
Metadata extensions used:

Generated by mp version 2.9.12 on Tue Oct 16 11:22:23 2018