Friday, March 6, 2015

PLSS CadNSDI - What’s in the Database

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

What is the PLSS CadNSDI?

The CadNSDI or the Cadastral Publication Data Standard is the cadastral data component of the NSDI.  This is the publication guideline for cadastral data that is intended to provide a common format, naming conventions, domains, structure and content for cadastral information that can be made available across jurisdictional boundaries, providing consistent and uniform cadastral data to meet business need that includes connections to the source information from the data stewards or data custodians.  The data stewards determine which data are published and should be contacted for any questions on data content or for additional information.  The cadastral publication data is data provided by cadastral data producers in a standard form on a regular basis.  Cadastral publication data has two primary components, land parcel data and cadastral reference data.  It is important to recognize that the publication data are not the same as the operation and maintenance or production data.  The production data is structured to optimize maintenance processes, is integrated with internal agency operations, and contains much more detail than the publication data.  The publication data is a subset of the more complete production data and is reformatted to meet a national standard so data can be integrated across jurisdictional boundaries and be presented in a consistent and standard form nationally.

The PLSS CadNSDI is the standardized form of the CadNSDI containing PLSS data.  This publication format provides a suggested minimum.  It is fully compliant with the intent of the standard for a data producer to include additional feature classes.  For example, there could be an added feature classes for recently monumented corners or mining claim lodes.
Similarly, it is fully compliant with the intent of the standard to add attributes to any feature class.  For example some jurisdictions identify corners that are photo-identifiable in the PLSSCorners Feature Class. It is also compliant to extend the length of any fields in the feature classes.  The field sizes are suggested minimum lengths.

Data sets will contain only available information.  A data steward cannot publish what is not collected.  For example, some states will have township and first division level data; others will also include second division polygons.  Some data sets have PLSSPoints and others do not. Over time it is expected that the content of all data sets will be developed and grow to be more similar in completeness.

The two most common question or comments about this standardized data have been
1.     There are too many features class, attributes, etc.
2.     There are not enough features, attributes, etc.

The Cadastral Subcommittee, through its consensus data standard development process, has agreed that this level of detail supports most business processes and is the best compromise between too many and too few.

What does the PLSS CadNSDI Contain?

The PLSS Cad NSDI database has this structure.

The Parcel Feature Data Set is included but it has not been populated for any of the CadNSDI data sets.  The Cadastral Reference Feature Data Set is the primary focus of the standardized data.

These are the cadastral reference features that provide the basis and framework for parcel mapping and for other mapping.
These are the cadastral reference features that provide the basis and framework for parcel mapping and for other mapping. This feature data set contains PLSS and Other Survey System data. The other survey systems include subdivision plats and those types of survey reference systems. This feature data set also include feature classes to support the special conditions in Ohio.

The Cadastral Reference Feature Data Set has the following feature classes

Each of these feature classes will be described more fully in other documents. 

The Cadastral Reference Local contains localized data that has not yet been integrated into the standardized data sets.  Typically these are localized data such as a portion of a county or a national forest area, where more accurate information or more complete information has been identified but the data steward has not incorporated this into the standardized data.  It is provide as a reference or as a notice that more current information may be available, although it is not in the standardized form and has not been fully evaluated.  After the localized data is incorporated into the standard it is removed from the Cadastral Reference Local Feature Data Set.  Feature classes will not have standardized names, but will include the localized data contributor in the name.  For example the following is an example from the Michigan PLSS CadNSDI, with BLM, Kent County and Oakland County PLSS Points submitted in the Cadastral Reference Local Feature Data Set.

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