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GIS Data

Imagery and geospatial data sources that can be used in GIS and mapping projects.

What is Geospatial Data?

Geospatial data is data that includes a spatial component. The location information in geospatial data sets can be presented in the form of coordinates (e.g., latitude and longitude), street addresses, cities, zip codes, etc. Geospatial data can be used to create maps and analyze data in GIS.

Geospatial Data Models

There are two primary geospatial data models: vector and raster.


Representation of the real world (grassland, lake, forest, marsh) in raster and vector data formats. Raster Data

  • Typically used to represent continuous data (e.g., temperature, elevation). Rasters can also be used to represent discrete data (e.g., land cover type).
  • Uses equal-sized pixels (cells) arranged in a grid to represent geographic data. 
  • Examples of raster data include aerial photographs, satellite imagery, digital elevation models (DEMs), etc.
     

Vector Data

  • Works best when used to represent geographic features with discrete boundaries (e.g., streets, land parcels, administrative boundaries, etc.)
  • Coordinate-based model where geographic locations are represented as points, lines, or polygon features.
  • Each geographic feature has associated tabular/spreadsheet data (i.e., attribute information).
     

Image source: MIT OpenCourseWare

Common File Formats

Some common file formats that work with GIS applications include:

  • shapefiles (.shp)
  • file geodatabases (.gdb)
  • Keyhole Markup Language (.kml or .kmz)
  • GeoTIFF (.tiff)
  • comma-separated values (.csv)
  • GeoJSON (.json)
  • GPS Exchange Format (.gpx)