Geography Reference
In-Depth Information
• SDTS, a data transfer standard for both vector and raster data 1
• Topologically Integrated Geographic Encoding and Referencing
(TIGER) data, used and distributed by the U.S. Census Bureau
• Digital Line Graphics (DLG)
There are a lot of raster formats you might encounter, including the
following:
• ERMapper Compressed Wavelets (. ecw )
• Erdas Imagine (. img )
• Digital Elevation Models (. dem )
• JPEG 2000 (. jp2 , . j2k )
• Multi-Resolution Seamless Image Database (MrSID) (. sid )
• GTOPO30, a global digital elevation model (DEM) derived from a
number of raster and vector sources
Some of the formats are open, meaning that they have a published
specification you can use to write applications and utilities that work
with the format. Others are closed, requiring you to use the vendor-
provided API. Of course, this is a concern only if you want to write your
own applications and utilities. If you're content with using the OSGIS
applications available, someone else has done the hard work for you.
Although it's not important to understand these formats to use them,
it does help to know a bit about them so you can determine whether
your favorite OSGIS software supports the format. In case you haven't
realized it yet, the GDAL/OGR library supports a huge range of vector
and raster formats—see Section A.2 , GDAL/OGR, on page 283 for lists
of additional vector and raster formats you might encounter.
The good news is if you are using OSGIS software that uses GDAL/OGR
for accessing raster and vector data (such as GRASS or QGIS), then you
have access to most, if not all, of the formats listed.
In Section 11.2 , Using GDAL and OGR, on page 186 , we'll look at using
the GDAL/OGR utilities to get information about our data as well as
convert and transform both raster and vector layers.
Web-Deliverable Data
Another “format” you'll encounter is data deliverable over the Web.
This category of data is often referred to as W*S. The moniker W*S is
See http://mcmcweb.er.usgs.gov/sdts
1.
 
 
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