Monday, September 14, 2015

Introduction to Creating GIS Maps

I'm not a huge data visualization guy, but a few of my recent posts have used mapping technology for illustrative purposes. I've received some questions on how to create the maps, or how to get started with mapping technology.  The process is actually quite straight forward, so I thought I would provide a simple tutorial to get us started.


METHODOLOGY

  • First acquire and install the GIS software you want to use.  I've posted on this before, but I like QGIS, which can be freely downloaded here.
  • Next acquire the map data that you want to use.  I suggest starting with Shapefiles, which are an industry standard format.  These provide the geographical data that can create the map as well as some attributes about each unit on the map.  Some examples of where to acquire this data include the Census Bureau, DASC, or local governments.  
  • Unpack the shapefiles.  You can get in the folder and take a look at these.  The most interesting is the *.dbf file, which can be opened in Excel, and gives the additional attributes for each unit.  So, for instance, if you downloaded a shapefile of Kansas counties, the dbf file would include attributes such as census population attributes and demographic breakdowns for each county.
  • Import the data into QGIS.  Here you use the "add a vector layer" function in QGIS.  See screenshot below, and click button.
  • Choose browse, and navigate to the shapefile directory.  In the directory, choose the *.shp file, click open and open.



  • Your shapefile should import, and look something like this.  By default mine imported as hot pink.  Not my choice.


  • The shapefile now shows up in the "layers" window, as something looking like the image below.  Right click on the name of the newly created layer in this box, and click on properties.



  • On the dialogue box click on style.  This allows you to play around with the styling of the data shown on the map.  You can choose different types of scales, a column from the shapefile to vary on, number of classes, and a variety of color ranges.  I chose to use a graduated scale, on the column "white", using color range of "blues" and five classes.  When you've chose what you want to do, click "classify", "apply" and "OK."





  • And your finished map.



This tutorial is designed to get you started using GIS technology through an easy interface, and simple first map.  There are virtually limitless possibilities of other things that you can do, from custom calculated fields to selecting specific elements to overlaying additional layers and geospatial queries.  There's even a module for advanced statistical and predictive analysis.  Once you get the basics of this tutorial down, you can explore forums and help pages on the internet, or simply reply to this post with additional questions.

No comments:

Post a Comment