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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 contains coordinate information (e.g., latitude and longitude), which allows features to be drawn on a map. Geospatial data can be used to create maps and analyze data in GIS. 

Geospatial Data Types

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

Attribute (Tabular) Data

Many geospatial data sets include an attribute table that provides additional information about the data set. Attribute (tabular) data can be used to perform queries and analyses, join data sets, visualize specific variables on a map, etc. Additional variables and calculations can be added to attribute tables using editing sessions, field calculator, etc. Attribute (tabular) data can also be uploaded to GIS software as standalone table and/or converted into spatial data using location information within the attribute table (e.g., geographic coordinates, street addresses, etc.)

 

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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)
  • LiDAR point cloud data (.las)
     

Convert File Formats

Many GIS software programs (e.g., ArcGIS, QGIS) include data conversion tools if you need to convert data into a different file format.