Mapping Hacks

Convert Geospatial Data Between Different Formats #68

Chapter 6, Mapping on Your Desktop

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HACK

available for that region, including data format and file size. Each data set is

delivered as a ZIP file with an eight-digit filename, which contains all the rel-

evant data and metadata. Download and unzip this file, and you should be

able to load up the data set in a GIS browser like QGIS or GRASS right

away.

The SDDS toolbar has a host of other nifty features. You can enter a lat/long

pair in decimal format to zoom directly to that location. Or you can click on

the map to get a lat/long coordinate for that point; unfortunately, this comes

in degrees, minutes, and seconds! You can also measure distances between

points and along a line that you describe by adding points. You can see ele-

vation data for a point by clicking on the map, or you can create an eleva-

tion profile, a 2-D plot of the ground topography between the points, useful

for line-of-sight evaluation for radio transmission.

The USGS Seamless Data Distribution System is an impressive example of

how much can be done to alleviate data-access pain in a relatively low-tech,

cross-browser fashion, with little more than JavaScript and flat images!

HACK

#68

Convert Geospatial Data Between Different

Formats Hack #68

The wide range of arcane GIS data formats can be confusing and difficult to

manage, but with the right tools, you can make quick work ...