Proposed GIS Minimum Metadata Standards

Proposed GIS Minimum Metadata Standards

Last Edit – 11/20/2015

Introduction

The adoption of standards for assessing and reporting quality indicators of GIS data would provide a tool that could effectively inform and guide data end-users in the proper use of a given dataset and/or its derivative products.

Proposed Minimum Metadata Content

v  - Required

v  Descriptive name/description/abstract: General overview of what the data set encompasses.

v  Purpose of the data and intended uses: What purpose and use was the data created for? (key data quality indicator)

v  Known errors and qualifications: Indicator of usability and constraints. (key data quality indicator)

v  Dates:  Creation, update, maintenance frequency.  Temporal information.

v  Contacts: General and/or maintenance. References for acquiring additional information.

v  Attribute information: Field metadata, for key fields at a minimum. Field metadata includes an explanation of each field’s content, and domain of values if applicable and especially for encoded values.

v  Limitations of use and/or distribution: Augments the intended use with specific use and/or distribution restrictions.

·         Feature type: Geometry type, e.g. point, line, polygon, raster, etc., or combinations thereof.

·         File name:  Name of the digital file(s), as delivered.

·         Projection/coordinate system:  Georeferencing information.

·         Data creation methodologies, processing and oversight: Including equipment used and whether or not an RLS was involved. How was the data created? Once the data was created, was it post-processed in any way that could affect its quality? (key data quality indicator)

·         Completeness:  Geometry AND attribute status in terms of what is missing.

See the following pages for examples.

Example Metadata for Pima County's GIS Parcel Layer

v  Descriptive name/description/abstract:  Pima County GIS parcel boundaries

v  Purpose of the data and intended uses: This GIS layer was created for general reference purposes, along with providing a graphical interface into parcel data that is maintained by the Assessor’s Office.

v  Known errors and qualifications: This layer contains duplicate taxcodes for parcels, e.g. undeveloped subdivisions in which all lots are assigned the same taxcode, until the lots are developed. Further, a relatively small number of other parcels have more than one polygon per parcel resulting in duplicate taxcodes. Subdivision common areas are typical examples. Parcels with duplicate taxcodes in paregion duplicate parcel valuation data. Summing valuations for these duplicated taxcode parcels from paregion will result in inflated totals. Users should normalize their analysis results based on the frequency of duplicate taxcodes.

v  Dates:

o Creation:   01/07/1997

o Maintenance:  Updated  daily

v  Contact(s):  Steve Whitney, steve.whitney@pima.gov, (520) 724-6729.

v  Attribute information:  Field metadata - (key fields)

Field Name	Description	Domain	Values
PARCEL	Parcel tax code	Range	Format: bbbmmppps – bbb = Assessor Book mm = Assessor Map ppp = Assessor Parcel s = Assessor Split
PARCEL_USE	ADOR parcel use code	Enumerated	Refer to the Arizona Department of Revenue’s Property Use Code Manual
TOTALFCV	Assessed total full cash value	Freeform	N/A
MAIL1 through MAIL5 and ZIP9	Owner name and mailing address	Freeform	N/A

o The attribute data for the layer primarily is supplied from the Assessor’s parcel data, along with some GIS overlays for other fields.

v  Limitations of use and/or distribution: This layer should not be used for determining legal boundary locations, surveying, engineering, or uses other than general reference. This layer is not to be distributed for commercial use without the permission of Pima County.

·         Feature type: polygon

·         File name: paregion

·         Projection/coordinate system: NAD83-92 (HARN), State Plane, Arizona Central Zone (FIPS Zone 0202), International Feet.

·         Data creation methodologies, processing and oversight: The majority of the parcel boundaries were tablet digitized from Subdivision Plats and Assessor Record Maps. In 2007 the parcel boundaries in the metropolitan area were rubber sheeted to digital orthophotography. Over time as new subdivision data has been acquired in digital format from development firms, this higher accuracy data has been incorporated into this layer and existing boundaries have been adjusted to this new data. Those involved in the creation of this GIS layer included GIS Managers, Analysts, and Technicians. GIS Technicians currently maintain the data.

·         Completeness: The GIS parcel layer is always incomplete in that there is lag time between the time that parcel data is recorded and the time that it takes to make its way through the recordation and assessment processes then into the GIS layer.  The attribute data is complete, although it may not be totally up-to-date due to lag times the parceling process. The parcel geometry and Assessor’s data is synchronized once a year at the close of the tax roll, producing a one-to-one match between parcel geometry and Assessor attributes.