Specifications

If you’ve ever zoomed around the
globe with Google Earth, you know
how much fun it can be to work with
geospatial data. When I need a diver-
sion, I often fire up Google Earth and
float above the skyscrapers of Manhattan
or revisit former stomping grounds.
For a deeper level of control with
geospatial information—where you’re
the chef who concocts the whole
stew—dive into a geographic infor-
mation system, or GIS. A GIS lets you
control all the elements that go into
the geophysical world you want to
explore. Stripping GIS down to its
essentials, you could call it computer-
based mapmaking. However, because
a GIS is powered by a database, the
opportunities for advanced analysis
are light-years beyond anything you
could do with a paper-based map. A
GIS not only will make you feel like
you have the world in your hands—
look out for that “I’m playing God”
feeling—but you also probably will do
something extremely useful with it for
your work or private life.
This article introduces a sample
project with Quantum GIS (QGIS),
one of the most advanced and pow-
erful open-source GIS packages for
the desktop. Although QGIS has
some excellent documentation, new
users might find the terminology a bit
stilted and missing some information.
The authors of the documentation
assume you already are familiar with
GIS and that you’re coming to QGIS
from a proprietary alternative, such as
the popular ArcGIS from ESRI. I, on
the other hand, assume you’ve never
used a GIS before.
A QGIS Test Project: Finding
a Place to Build
To illustrate some basic functions of a
desktop GIS, I use QGIS to make
preparations for a fantasy of mine,
which is to create an ecologically
friendly real-estate development. In
this exercise, I locate a parcel of agri-
cultural land in Washtenaw County,
Michigan, near Ann Arbor, where I
can restore a former wetland and
build a cluster of homes nearby. I
chose Ann Arbor due to its proximity
to drained wetlands in rural areas,
as well as local demand for homes
in areas with lots of wildlife.
To accomplish this task, I explore
how to load QGIS on your system; find
the geospatial data for the task; load
that data into QGIS; and view, set up
and analyze that data to do the job at
hand. Along the way, I introduce key
concepts and important terms.
Getting QGIS on Your System
QGIS has a useful, comprehensive Web
site with plenty of resources to get you
started. Beyond the free application
download, you’ll find a wiki, help
forums and loads of documentation.
QGIS has versions for Mac OS X,
Windows and several variants for Linux
users: source, Debian, Ubuntu Gutsy
and OpenSUSE. Given that repositories
are provided, installation should be easy
and straightforward. All you need to do
86 | august 2008 www.linuxjournal.com
INDEPTH
Quantum GIS:
the Open-Source Geographic
Information System
Exploring Quantum GIS (QGIS) using an example of real-estate planning. JAMES GRAY
Figure 1. The application QGIS 0.10 offers a clean, intuitive user interface.