Starter Dictionary

Edit Tracker

2007-12-21

• Added ESRI Shapefile and Shapefile entries. (The Sunburned Surveyor)

---

Entries

ESRI Shapefile

Simple Definition: A file format created by ESRI that is used to store simple geospatial features.

Additional Explanation or Clarification: A Shapefile is represented at a minumum by a file with a DBF extension and a file with a SHP extension. An index file with a SHX extension may also be included. Shapefiles only store a single geometry type. They can optionally store z ordinate and "m" ordinate values in geometry coordinates.

Example: The United States Census Bureau TIGER Data can be obtained for most counties in the United States as ESRI Shapefiles. Visit this page to for downloads of these Shapefiles.

Associated Terms:

• Gespatial Data

Also Known As:

• Shapefile

References: Wikipedia Shapefile Entry

Links: ESRI Shapefile Specification

GDAL Shapefile Information

Geospatial Data Set

Simple Definition: A set or group of geospatial data with a common theme or association.

Additional Explanation or Clarification: Features belonging to a geospatial data set typically share a common feature schema or set of feature attributes. The term does not typically refer to a single feature. Geospatial datasets are often represented in a GIS by a thematic layer. Geospatial datasets are typically the main elements in a GIS Data Model.

Example: An ESRI Shapefile with a set of line features representing city streets could be called a Geospatial data set.

Associated Terms:

• Gespatial Dataset Definition

Also Known As:

• Data Set

References:

Links:

Geospatial Metadata

Simple Definition: Information about geospatial data that may not be contained in, or readily apparent from, the geospatial data itself.

Additional Explanation or Clarification: Metadata is often defined as "data about data". As an example, you might have metadata for a document might include the following information:

• Identify the purpose of the document.
• The date the document was written.
• The date the document was last revised.
• The author.

Geospatial Metadata is information about a geospatial dataset that may not be contained in, or may not be readily apparent from, the Geospatial dataset itself. For example, you could view the coordinates of feature geometry in a vector data set, but may not be able to determine the spatial reference system from the coordinate values. You could view the name of a feature attribute, but that may not indicate what aspect of the real world that attribute represents. This is the type of inormation that can be encapsulated in geospatial metadata.

Example: Information about the [Example: An feature schema or feature attributes common to a group of features. This might include the meaning of the attribute name, the data type of the attribute, and rules for the creation, deletion, and modification of the attribute values.

Associated Terms:

• Metadata Standard
• FGDC Metadata

Also Known As:

• Metadata
• GIS Metadata

References:

• Wikipedia Geospatial Metadata Entry
• Wikipedia Metadata Entry

Links:

• Main FGDC Metadata Web Page
• FGDC Metadata FAQ

Geospatial Metadata Instance

Simple Definition: A single and specific metadata document, typically created in conformance with a metadata standard.

Additional Explanation or Clarification: There is typically a metadata instance for each geospatial dataset in a GIS. The term "metadata instance" can be used to distinguish a specific metadata document from all metadata documents that conform to a particular metadata standard, or from the metadata standard itseld. (In a similar way, an isntance in object-oriented programming is different than the class or interface to which the instance conforms.)

You could think of a metadata standard as a cookie cutter, and a metadata as an individual cookie made from that cookie cutter.

Example: If you had a GIS that managed road data and car accident data in ESRI Shapefiles, you would have a metadata instance for each shapefile. One metadata instance might be named roads_metadata.txt while the other was named car_accidents_metadata.txt.

Associated Terms:

• Metadata Standard
• Geospatial Metadata

Also Known As:

• Metdata Document

References:

Shapefile

See ESRI Shapefile