What is geospatial data and how can this data be used for geographic information systems (GIS)? Geospatial data includes information related to coordinates such as latitude and longitude and allows features to be drawn on map. A Geographic Information System (GIS) is defined by the U.S. Geological Survey as "...a computer system that analyzes and displays geographically referenced information" (What is a geographic information system (GIS)).
Essentially, GIS links spatial information (i.e., location based data) with description information (descriptive data) and can capture, store, manipulate, analyze, mange, and present geospatial data. Examples of GIS might include the location of utilities in a given town or soil conditions in a defined area. We can use GIS to show geographic changes over time, track weather patterns, or provide health information to the public. (Adapted from Johns Hopkins University. Sheridan Libraries. Geospatial Concepts).
This guide provides an overview of geospatial data types as well as the tools and software related to geospatial data and geographic information systems (GIS). It can also help you to locate related datasets and resources to help you build your background knowledge about GIS.
Vector data and raster data are the two most common geospatial data models, although many geospatial data sets include attribute or tabular data to provide additional information about the dataset.
Vector data represents discrete data values. These values have separate, distinct values that can be counted and in GIS we store vector data using:
Vector data works best when it is used to represent geographic features with discrete boundaries such as streets, land parcels, and administrative boundaries. Below is an example of vector data pertaining to squirrel populations in Central Park from the Squirrel Census.
Raster data can represent both discrete and continuous data values. Continuous data values fall with an infinite spectrum of numbers and can be measured to any decimal place. In GIS raster data is stored using cells and pixels that are organized into a grid. Each cell represents a data value. Examples include:
(Adapted from Brandies Library. GIS Data)
GIS software and tools include a number of different file formats. It is important to keep in mind that not all software packages are compatible with each file format. Below are a few common GIS file formats that you may encounter.
Additional information can be found at the GISGeography list of GIS Formats and Geospatial File Extensions.
0000-0001-9157-3178
