Geography Reference
In-Depth Information
A lot of times data is distributed in a form that's convenient for the dis-
tributor, not the end user. This is probably the most common circum-
stance you'll encounter when gathering data from the Internet. Let's
take an example.
Importing an E00 Interchange File
Harrison is interested in some data from his local state government. He
soon discovers that they, like a lot of other government entities, deliver
their data in a format called an E00 file. 3 To make use of the data,
Harrison has to convert it into a format his software supports. He has
several options for converting the interchange file. First he can search
around the Internet for one of several E00 to shapefile converters. 4 The
other option is to use GRASS to import it right into his favorite mapset.
Once in GRASS, 5 he can also export it in a number of formats to share
with his friends. To convert an E00 interchange file to GRASS, Harrison
uses the following:
GRASS 6.2.2 (alaska_albers):~ >
v.in.e00 file=/home/harrison/itma.e00 type=area vect=quad_boundary
Importing areas...
Over-riding projection check.
Proceeding with import...
Layer: LAB
WARNING: Column name changed: 'ITMA #' -> 'ITMA_'
WARNING: Column name changed: 'ITMA-ID' -> 'ITMA_ID'
WARNING: Column name changed: 'TILE-NAME' -> 'TILE_NAME'
Importing map 3011 features...
Layer: ARC
WARNING: Column name changed: 'ITMA #' -> 'ITMA_'
WARNING: Column name changed: 'ITMA-ID' -> 'ITMA_ID'
Importing map 6705 features...
-----------------------------------------------------
Building topology ...
Imported area vector map <quad_boundary>.
.... more messages ....
Done.
GRASS 6.2.2 (alaska_albers):~ >
If Harrison needs to share the new layer with somebody, he quickly
creates a shapefile using v.out.ogr .
This is an ArcInfo interchange format that is not directly usable by most GIS software.
3.
Such as http://avce00.maptools.org
4.
If you need help getting GRASS started, see Appendix C , on page 296 .
5.
 
 
 
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