Mapping Hacks

Become a GRASS Ninja #77

Chapter 6, Mapping on Your Desktop

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HACK

the direction in which GRASS ninjahood might lie. In the process, I want to

show why open source GIS in the Unix environment is at least as good, if

not better—for values of “better” that might be important to hackers—than

any flashy, GUI-laden, commercial GIS application you can imagine.

Objective #1: Secure the World’s Borders

The objective for this GRASS ninja-training mission is to obtain a high-qual-

ity vector map of the world’s contemporary international borders,

*

with

attribute values identifying which country each polygon belongs to. Ideally,

the map should have no restrictions on its use and redistribution and be

suitable for creating derivations, such as SVG base maps and so on. That’s

all. Nothing fancy. Right?

Well, you might think so, and if you weren’t me, you might be right. But my

coauthors and I searched high and low on the Web for a decent vector map

of the world’s international borders, and we didn’t find one straight off the

bat. We found a bunch of old data, like VMAP0, formerly known as the

Digital Chart of the World, which is also a bit large and unwieldy to work

with. We found out how to get the polygons out of the Generic Mapping

Tools (see “Experiment with Different Cartographic Projections”

[Hack #28]),

only to discover that the countries weren’t identified. We found different

services, such as ESRI’s world ...