Saturday, March 7, 2015

PLSS CadNSDI - Metadata at a Glance

This is the second of a series of documents that describe the contents of the PLSS CadNSDI data set.

The Metadata at a Glance is an unlikely first feature class to select to use but the information in this feature class will rapidly show the data stewards and currency of features in the rest of the data set.  As the PLSS CadNSDI expands and more locally sourced control and divisions are incorporated into the data set, there will be increasing numbers of contributors.  This is the feature class that can be used to quickly and easily see updates. 

The Metadata at a Glance is a geographic representation of the data stewards and currency or vintage.  The initial or baseline data set is based on PLSS Townships in PLSS areas. In non-PLSS areas the metadata at a glance is based on a data steward defined polygons such as a city or county or other units. The identification of the data steward is a general indication of the agency that will be responsible for updates and providing the authoritative data sources. In the shared environment of the NSDI the data steward for an area is the primary coordinator or agency responsible for making updates or causing updates to be made. The data stewardship polygons are defined and provided by the data steward.

The standard attributes for this feature class are listed in the table.

Concatenation of the principal meridian, township, range, and duplication code that form a unique id.
Township Identifier
Township label that is used for cartographic output or web display.
Township Label
Data steward for the cadastral reference data. The data steward is responsible for the authoritative data
Data Steward
The last date of any revision in the data steward defined polygon
Revised Date
The two letter postal abbreviation for the state
State Abbreviation
This is a unique identifier for the stewardship polygon.
Stewardship Polygon ID
This is the type of polygon for the metadata at a glance. Examples include PLSS Township, Survey Township, County or City
Stewardship Polygon Type
This is a label for the stewardship polygon for cartographic purposes
Stewardship Label

In the figure below a portion of the Idaho PLSS CadNSDI is shown illustrating an area where there are three data stewards.

The PLSS Township was selected as the initial unit of maintenance for this feature class because typically PLSS data is updated on a Township basis.  

In the image below the polygons are shaded with the Data Steward and labeled with the last revised date.  This figure is from the Mississippi PLSS CadNSDI.

The initial data set reflects the nationwide collection and standardization efforts.  As this data set continues to be updated the analysis and information in the Metadata at a Glance will grow, the unit of maintenance will become better defined, and more granular.  Potential expanded attributes data stewards may consider will be links to contributor geospatial metadata, statements of overall accuracy, and aggregated or compiled date.  Individual users may want to add fields to track download or access dates.  All of these expansions are compliant with the standard intent.

The analysis that can be done and the functions this feature class can support for data set management are numerous, especially in shared maintenance and web service environments.

This feature class is the manifestation of the metadata for aggregated data described in this blog

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