Geography Reference
In-Depth Information
Free the Data!
There is a lot of data around the world that is either locked up,
expensive, or generally unavailable. As we mentioned before,
this varies depending on where you are in the world.
There is a movement afoot (actually it's developing on many
fronts) to free up data. One example was the “ransoming”
∗
of the U.S. Geological Survey's (USGS) Digital Raster Graphic
(DRG) topographic maps. These maps are available online
from various sources, some free and some not. To make all the
data available in one place free of charge, the maps were pur-
chased and then “held hostage” until contributions equaled
the cost. The maps were then given to the Internet Archive to
be made available to everyone for free.
Another effort underway in Europe is the Public Geo Data
effort.
†
This effort seeks to liberate publicly collected data and
make it available at no charge.
∗.
†.
2.9
Where to Find Data
By now you realize (or already knew) that without data, we can't do
much with OSGIS. For those of you already deeply entrenched in the
GIS world, you pretty much know where to search for data. Feel free
to skip ahead. If you are just getting started with GIS, this is a pretty
common question. Your desktop GIS toolkit isn't much good without
any data to play with.
The availability of free data depends on where you are in the world. If
you are lucky, you live in a country that freely provides data collected
by the government. If you are not so lucky, you may have to pay, some-
times quite steeply, to get the data. Don't despair—there is a lot of free
data available to get you started.
In reality, there are two types of data: base data and “your” data. Base
data is just that—you lay it down as a base for the rest of your map.
Examples of base data are country boundaries, rivers, towns, and the
DRG that Harrison downloaded in our first encounter with him. Your
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