Project Glossary of Terms

Terms for objects in the Big Ten Academic Alliance Geoportal

Record: An individual entry to be included in our geoportal. Synonym: item

Metadata: The information describing the resource.

Resource: The digital object that is being cataloged. Synonyms: data, dataset, map. Types of resources:

  • Vector file: A type of GIS dataset made up of points, lines, polygons.
  • Raster file: A GIS dataset made up of pixels, such as satellite imagery or elevation models.
  • Georeferenced scanned map: A special format where a scanned image has a linked file that stores spatial information. This allows the scanned map to be viewed as a layer in a GIS program or on a digital map.
  • Un-georeferenced scanned map: A scanned map stored as an image file, such as TIFF or JPEG. The presence of coordinates in the record’s metadata does not make the map georeferenced.
  • GIS Web Service: A streaming GIS layer that can be viewed and queried in a browser or GIS application. Examples include WMS, WFS, or Esri.

Collection: A group of records categorized by the clearinghouse or library they originated from. Examples include "Maryland iMAP" or "John R. Borchert Map Library." (Note: this definition is specific to our project.)

GIS data formats

Shapefile: An open source geospatial vector data format containing a small bundle of files.

Raster Dataset: A raster format used in ArcGIS Geodatabases OR a generic term for a raster file.

Geodatabase: A proprietary ArcGIS file or database format that can hold multiple geometry types, spatial referenece, attributes, and behavior for data OR a generic term for a spatial database.

ArcGRID: Short for ESRI ArcInfo Grid or Esri Grid. A raster format expressed as a binary or ASCII grid.

GeoTIFF: a TIFF image file with geospatial information embedded with it.

Coverage: A deprecated proprietary format from Esri that can store multiple spatial geometries, topologies, and attributes.

Attribute Table: A tabular file or database of the information associated with features or cells in a spatial dataset.


Scanned/ digitized maps terminology

Georeference: The creation of link tables describing control points that tie raster files (i.e. scanned maps), to specific locations on a reference basemap. The result of any georeferencing activity will produce an estimate of positional accuracy based on an assumption that the reference layer is perfect. Georeferencing can be carried out to different standards of accuracy based on user-defined requirements.

Feature extraction: The creation of a GIS feature layer (e.g. shapefile), of features (e.g. points, lines and polygons), from a georeferenced raster file (i.e. scanned map). Synonyms: vectorization, digitization-(outdated)

Geotag: This term means to add geospatial metadata to media. It is often confused with "georeference," but is more specifically considered a metadata attribute. In practice, geotagging typically entails adding one coordinate or point that is used to locate a photo or media object.

Geocoding: the matching of postal or other street and number addresses to specific locations on a reference layer, or vice-versa (sometimes called reverse geocoding).

Metadata Formats

General terms

Metadata Standard: Formal guidelines for content that been have approved by a recognized standards organization.

Metadata Schema: The structure and format of how a metadata standard is implemented.

Metadata Profile: A community's version of a metadata standard.


Official standards used by this project

FGDC CSDGM: Federal Geographic Data Committee Content Standard for Digital Geospatial Metadata: One of the oldest metadata standards for GIS vector and raster data. Usually referred to simply as "FGDC." The preferable format is XML, but FGDC is also stored as TXT or HTML.

ISO 19115: A standard from the International Standards Organization for many types of geospatial resources. The ISO formats used for this project are:

  • ISO 19139: The XML expression of the ISO 19115 standard. It contains: identification, constraint, extent, quality, spatial and temporal reference, distribution, lineage, and maintenance of the digital geographic dataset.
  • ISO 19110: This is an additional, optional XML file that can be created that contains the feature catalog, a listing a dataset's attribute types along with information including definitions, descriptions, and frequencies.

Dublin Core: A widely used set of key elements designed to be web semantic and interoperable.

MARC (MAchine Readable Cataloging): A general metadata standard developed in the 1960s and universally adopted by libraries.


ArcGIS internal storage formats for metadata

ArcGIS 1.0 Metadata: The current proprietary format used by ArcGIS. It contains all elements required for either FGDC or ISO (as well as other profiles). It also contains technical information specific to the ArcGIS environment, such as thumbnails. Also referred to as ArcGIS 10 metadata.

ESRI-ISO: The format used by ArcGIS Desktop applications up through version 9.x. It is based on the ISO standard, and can be identified by the phrase ESRI-ISO in the metadata.

ESRI Profile of the Content Standard for Digital Geospatial Metadata: The FGDC format used by ArcGIS Desktop applications up through version 9.x. It is based on the FGDC standard, and can be identified by a reference in the metadata file to a document type definition (DTD) called esriprof80.


Geoportal specific schemas

GeoBlacklight Schema: A combination of Dublin Core, GeoRSS, and custom elements that can be extracted from a geospatial metadata standard file.

OpenGeoportal Schema: A set of elements derived from a geospatial metadata file to be ingested by OpenGeoportal to facilitate discovery.


Subcategories of metadata

(This project splits the metadata into three types, but this may or may not align with how other projects use the following terms):

  • Descriptive Metadata: Descriptive information that must be entered by a person, either manually or with a template.
  • Technical Metadata: Information about a digital object that can be machine generated for the metadata file. Examples for GIS datasets include spatial extents, reference system, and entity/attribute information.
  • Administrative Metadata: Templated information added to a metadata record that informs its provenance and source. Examples for this project include institution, collection, usage disclaimers.

Metadata File Formats

  • XML (eXtensible Markup Language): A file using attribute value pairs within tags to structure and define metadata. It can also use codes to require conformance to pre-defined vocabularies.
  • JSON (JavaScript Object Notation): A file using the format key/value pairs for metadata exchange. It is more lightweight than XML.
  • CSV (Comma Separated Values): A flat file for storing tabular data.

Tools & Applications

Metadata Tools

Oxygen: A desktop application for creating and transforming XML files.

ArcCatalog: A Windows-only application that is part of the ArcGIS for Desktop suite.

ArcGIS Online: An online application for sharing geospatial resources that has recently (as of 2015) added metadata editing capabilities. It uses the ArcGIS metadata format.

GeoNetwork: An online application specifically designed for cataloging geospatial resources using the ISO metadata standard.

Omeka: An online application for general management of digital objects using the Dublin Core metadata standard.

MarcEdit: An editor for MARC metadata that includes batch editing and transformations.

OpenRefine: A general tool for cleaning and normalizing data, especially useful for keywords.


Geoportals

OpenGeoMetadata: This is a collaborative initiative hosted on GitHub that holds ISO geospatial metadata for resources from many different institutions.

GeoBlacklight: Open source Ruby on Rails discovery portal for geospatial data based upon Blacklight.

OpenGeoportal: This refers to both a geoportal platform as well the name of a working group that includes many of our task force members. The group is a collaborative effort to share resources and best practices in the areas of application development, metadata, data sharing, data licensing, and data sources in support of geospatial data repositories.

ArcGIS Open Data Portal: A geoportal that uses the ArcGIS Online platform to allow users to organize and publish their data.

CKAN (Comprehensive Knowledge Archive Network): An open source data platform that can be used for geospatial data.

Socrata: A proprietary hosted platform for distributing many forms of data, including geospatial.