Introduction - Desktop GIS: Mapping the Planet with Open Source Tools - page 9

This is a simple example of the type of analysis you can do with open
source GIS applications available today. You may be thinking that Har-
rison's analysis is a bit contrived and really not all that significant—and
you are probably right. Let's list a few more situations where a buffer
analysis might provide meaningful insight:

• Restrict development to a distance at least 500 meters from an
active eagle nest.
• Determine where to allow a drinking establishment such that it's
at least a quarter mile from any school.
• Develop emergency action plans by identifying all public facilities
within a given distance of a hazardous storage site.
• Establish a setback around a creek or stream.

And the list goes on. As you can see, the simple operation of creating
a buffer can answer a lot of questions. It's a valuable tool and just
one of many that we'll take a look at as we get deeper into specific
applications. Of course, there are a lot of other types of analysis we can
do with desktop GIS. We'll explore some of these later.

We've now taken a look at three aspects of GIS: visualization, digitizing,
and analysis. With that under our belt, we are ready to get into some
more specifics. Oh, and about Harrison—he finally proved his point by
creating a 5,000-foot buffer around all the lakes. As usual, the tools
alone can't provide a meaningful analysis. Before we move on too far,
let's take a quick look at the server side of things.

1.2 Desktop vs. Server Mapping

When you think of a server, you probably think of a big machine locked
away in an air-conditioned room somewhere. Well, that could be true,
but in this case I'm referring to software, not hardware.

The server side of open source GIS provides important capabilities for
us on the desktop. For example, we might have spatial database that
stores our data. Or we might have a spatial server that can pump
out data using a number of web standards. We can use all these data
sources from the desktop.

We might have resources on a bunch of servers, all accessible from our
desktop GIS applications and serving up all the data we need. We're still
doing desktop mapping, using the tools installed on our local machine.
Let's contrast that for a moment with server-side mapping.