Dan MacFarlane and Jim Clifford
So far in this blog post series [part one, part two] on GIS mapping we have been discussing using Google software. But now comes the big jump. So far, Google has kept the GIS learning curve very low. But to go much further Dan needed to actually start learning dedicated GIS software.
There are several ways to do this. One of the most obvious is to consult the GIS-map librarian at your university library. Many of them are dying to help you out [see Jennifer Bonnell’s post], and it is free and – assuming you live near your campus – accessible. Your university might offer classes and workshops as well. Jim got started this way. You can also consult a friend or colleague familiar with GIS mapping. Dan’s been lucky enough to have access to Jim, as well as a number of others with experience in GIS. Moreover, three CHESS events – Saskatoon, Vancouver and St. Andrews – included great sessions on GIS, so many of you will by now have had a basic introduction.
ArcGIS is the most common software, and you may be able to get a free one year academic license from your university, or use it for free on a university computer. If you can get a copy and you have a MS Windows machine to run it on, you should (future posts will increasingly focus on using ArcGIS). However, if you cannot get a university licensed copy, ArcGIS is very expensive to purchase and doesn’t work on Mac or Linux computers (though you can, for a few hundred dollars, install Windows on your Mac and then install ArcGIS). A free alternative is QGIS, which works for Mac and Linux. Although QGIS is not nearly as powerful as ArcGIS and it has a number of bugs that make it frustrating to use at times, it is still an impressive piece of software considering the price. This post will focus on becoming familiar with basic GIS functions using this accessible software. Future posts will demonstrate the same functions of ArcGIS and discuss some of the advantages of using this proprietary and very expensive software.
Most GIS guides tend to a considerable amount of time discussing the nature of a GIS database, the ways different kinds of data relate to each other and most importantly, they discuss the reasons you should or should not use GIS for your project (See A Place in History). While these are important topics and ones you need to consider carefully before dedicating months or years to developing a complex GIS database, we think readers should get their hands dirty and play around with some GIS software first. Following the successful approach taken by William Turkel and Alan MacEachern in the Programming Historian, we think a hands-on introduction will give you the skill and vocabulary so you can make a better informed decision about whether to peruse GIS further. This is all the more reason to start with the free and relatively easy QGIS software.
Downloading and Installing QGIS
You cab download QGIS from this website: http://www.qgis.org/wiki/Download You should choose the standalone installers if you use Windows or Macs.
Once you install the software, open it.
There are two main kinds of spatial data used by GIS software: Vectors and Rastors. Vectors are the lines, points and polygons that you might be familiar with if you’ve looked at maps created by another historian using GIS software. Rastors are digital images (such as a scanned map or an aerial photograph) and use the same formats that most people are familiar with from their digital cameras: JPGs or TIFF. For the next few blog posts we will focus on loading, using and finding vector “shapefiles”. Later we will turn out attention to adding scanned historical maps as crucial layers in a historical GIS database.
Many cities in Canada make their GIS data available for free. This is a huge advantage for historians studying urban settings, as it provides a great base upon which you can build a database. Toronto’s “centreline” shapefiles and its “city ward” shapefiles are both available online and the data is open, so you can download it for free. Download and unzip the two folders. Place them somewhere in your computer file system where you can find them easily.
Return to QGIS and click on the “Add Vector Layer” button. Click on “Browse” and find the folder where you saved the two unzipped files with shapefiles in your computer’s file system. Click on the files “tcl3_icitw.shp” (in the Wards folder). This should load the city’s wards on your screen. Repeat this step clicking on “TCL3_CENTRELINE.shp” (in the centreline folder). Now your screen should look similar to the images attached to this blog post.
Now that you have some data on your screen you can use the tools in the the two menus seen in the image above to move around the data, zoom in and out, and to click on the data to see the linked information. Take some time to explore these Toronto vector layers. Use the identify tool (the yellow arrow points to it above) to click on one of the thousands of lines that make up the centreline layer or one of the wards (depending on which layer you click on in the side panel). It will create a popup screen with all the extra information about that line, including its name and its category (major arterial road, freeway, river). As a historian, you will be able to create your own datafield for your historical data (year the road was built or infant mortality rates in different wards) for vector layers and use them to represent historical trends on your maps. However, that is the topic for a future posts. In our next posts we will build on the work we did today by showing you how to search for shapefiles related to your own research project. In the meantime, get in touch with your map librarian and see if they can help you find some good base layers.