Library:HSS GIS Data Search Caveats

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Searching for GIS data sets online can be frustrating and time-consuming. Here are some things to keep in mind as you go through the process.

Finding Data

  • Allow enough time to find data.
It can take quite a few hours or days of searching to find the data you need
  • The data may be within a greater data set that covers many topics.
For example, glaciers may be in a land cover data set or grocery stores may be within a points-of-interest data set
  • Data sets may cover a larger area than you are looking for.
Although your study area may only be around one municipality or landform, the data may exist at the provincial, state or national level

Downloading Data

  • Data sets may be compressed.
Large files may be distributed in a compressed format with extensions such as .e00 or .tar.gz. Specialized software may be required to uncompress the files. If you need help with this, the GIS Librarian can assist you.
  • Data sets may not be free.
Some government and many commercial data products may require a fee to access the data. Most Canadian and American government data sets are free. Outside of North America it is difficult to find detailed data sets at no cost. Check for open or crowd-sourced data, as this is becoming more popular in developing countries. (See the International Data Sources page of the Geomatics website for a list of major open data sites.)
  • Data sets may not be GIS-ready.
The information you are seeking may be in tables or reports. You may need to put the data into a format that can be read by GIS software (such as by adding columns for latitude and longitude coordinates).

Evaluating Data

  • Check the level of detail.
At what scale was the data created? The Vancouver coastline will not be represented well in a shapefile created at 1:1,000,000 and covering all of Canada. If metadata is present, check to see how the data set was created and what error might have been introduced in its development.
  • Check the attribute table.
Does the data set include the information you need? Can you interpret the values in the attribute table? Is there a metadata file to describe the attributes?
  • Check the time period.
Does the data set's creation date correspond with your project? How does it correspond with other data sets you are using?

Three Key Tasks to Remember

  1. Download the Metadata
  2. Document where you downloaded the data sets as you go
  3. Review the data set's licence (if applicable) for use restrictions and citation requirements