Geospatial metadata

Metadata can be defined as data that describes and gives information about other data. Geographic metadata is used to document geographic data resources—for example database files and data within a Geographic Information System (GIS), geospatial databases, and earth imagery. Geospatial metadata can also be used to document geospatial resources that may include data catalogs, mapping applications, data models, and related websites. Geographic metadata provides context for the data and helps to apply it through various kinds of information, such as who the data was developed by, when it was collected, how it was processed, how its attributes are defined, the formats in which it is available, and how it can be obtained.

The core components of a geographic metadata record include the following:

• Metadata record information, including the language in which the record is written, a unique file identifier, the metadata standard used to organize the record, a point of contact, and the date on which the metadata record was written

• Identification information, including the title, abstract, purpose for creation, status, keywords (theme and place), and extent (temporal, vertical, and horizontal)
• Constraints information related to legal and security limitations to use of the data and access to it
• Data quality information related to the processes and sources employed to develop the data as well as positional and/or accuracy assessments undertaken
• Maintenance information related to the scope and frequency of data updates
• Spatial representation indicating the mechanism used to represent spatial data (grid, point, vector)
• Reference system information related to the reference systems used to represent geographic position and time
• Content information about the data set entities and attributes
• Symbology information about the symbols used to represent spatial features
• Distribution information about the data distributors and methods for obtaining the data
• Metadata extension information about custom, user-based changes to the elements, domains, or conditionality of the standard
• Application schema information about the schema or data models employed to structure the data.