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Research Commons

A space and place for those seeking help with research-related needs.

Terms & Vocabulary

  • Raster image - a shape file (think of a park coded as a square area).  Such a shape entity can not be easily manipulated and analyzed.
  • Vector image - object composed of points with both spatial and value descriptors (This complex object can be manipulated and analyzed.)
  • Georeferencing - describing an object's location within a spatial grid (for example, longitude and latitude). Such objects can be over-layed with other objects (as layers) with a similar frame of reference.  Imagine overlaying streets, bus routes, and parking lots.
  • Layers - data sets that can be added to other data sets and overlayed onto a spreadsheet and/or map grid. Imagine railroad tracks, rivers, gas stations.
  • Datum - a standard for calibrating spacial relationships and references at a given time.  Imagine the exact location of earth's continents on Jan 1, 1995.  These spacial objects move in relation to each other, so you must be careful to use similar calibrations when overlaying data sets. 
  • Projections - various ways to represent a round object on flat surfaces or maps. Different projections provide skewed approximations and can result in significant distortions in relative sizes from North to South, top to bottom, etc.
  • Scripts - programs written to perform various manipulations on data sets. Imagine defining vegetation types from the color of reflected radiation patterns.

Geospatial data are electronic data that include some kind of location information, which could be latitude longitude coordinates, an address, a zip code or a county. These data are generally used in Geographic Information Systems (GIS), cartography, and remote sensing software packages. Data can be obtained from central clearinghouses (see the Sources box, below), local organizations, and/or generated by researchers in the field.

From the interesting GIS Lounge portal:

There is a distinct difference between GIS and Geospatial data, in that GIS refers more narrowly to the traditional definition of using layers of geographic data to produce spatial analysis and derivative maps.  Geospatial is more broadly used to refer to all technologies and applications of geographic data.  For example, popular social media sites such as Foursquare and Facebook use “check-ins” that allow their users the ability to geographically tag their statuses.  While those applications are considered to be geospatial, they don’t fall underneath the stricter definition of what makes up a geographic information system.

There are two basic geospatial data models:

  • Vector
    • Coordinate-based data model that represents geographic features as points, lines, and polygons
    • Tabular data is associated with each vector feature
    • Common formats include Shapefiles, File Geodatabase Feature Classes, and few others
  • Raster
    • Pixel-based data model that defines space as an array of equally sized cells arranged in rows and columns
    • Each cell, or pixel, holds one value, but can also contain more than one band to hold more than one value
    • Common formats include TIFF, JPEG, MrSID, Esri GRID, File Geodatabase Raster, netCDF, and many others!

From UIUC LibraryGuide Geospatial Data

Sources

Tools