| Retrieving
Internet Data
Introduction
Many spatial data layers are available free of charge over
the Internet that pertain to the Northern Puget Sound Ecological
Characterization (NPSEC) project area, as well as the entire
State of Washington. The Washington State Geospatial Clearinghouse
is a primary facilitator of spatial data for the public of Washington,
but data are also available from other organizations focused
specifically on areas within northern Puget Sound. Any number
of spatial data layers from these organizations can be used
in conjunction with the NPSEC geographic information system
(GIS) to meet specific information needs and objectives. Because
many data layers are distributed through the Internet, it is
important to understand how to download these files to your
computer.
Most spatial data available over the Internet have to be downloaded
as zipped files. A ZIP file consists of several individual files
packaged together into a single file. Usually, the files in
a ZIP file are compressed so that they take up less space in
storage or take less time to send to someone. Once a ZIP file
has been downloaded, the files that are contained within the
ZIP file must be extracted, or "unzipped". If necessary,
decompression of these files also takes place during the unzipping
process.
A common spatial data format is an ESRI® file type called
a "coverage." Coverages exist in conjunction with
other files that contain specific information about them and
are typically transported over the Internet as zipped Interchange
(.e00) files. Interchange files provide a safe mechanism in
which to transfer all files associated with the coverage. These
files have to be "unzipped" after download, and in
order for the unzipped Interchange file to be used with ArcView
8.x, a special import process must then be performed within
ArcToolbox® to convert the file back into a coverage.
Information on importing different file formats into ArcView
can be found in the Help menu of your ArcView software. This
tutorial illustrates how to download a zipped Interchange (.e00)
file from the Internet to your computer and then shows you how
to import the Interchange (.e00) file for use in ArcView 8.x.
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Downloading
Zipped Files
Navigate with your Web browser to the Washington State Geospatial
Clearinghouse at http://wa-node.gis.washington.edu/
and then select Contacts and Partners.
Scroll down to the section entitled Data
Providers. Beneath this heading is a growing list of
Washington agencies and organizations that have GIS spatial
data available through the Internet. Within this list, click
on Washington State Department of Ecology.
This link takes you to the home page of the Washington State
Department of Ecology. Click on Quick Links and then
on GIS data / maps.
Click on Data.
Scroll down the page until you see the data layer named Dairy
Farms - 2002. Now click on the E00 icon.
After selecting this icon, an on-line digital data agreement
will open that must be filled out before downloading data from
the Washington State Department of Ecology. After reading the
agreement, scroll to the bottom and fill out the form and then
click the Download dairy.zip button.
You may be prompted to choose a location in which to save the
zipped file. Your hard drive will work as well as any other
location; however, be sure you remember where you are saving
it. Once you have designated a location, click the Save
button.
You have now downloaded the zipped file. Locate the zipped
file entitled dairy.zip by navigating to its location using
My Computer or Windows® Explorer.
The next step requires that an unzipping software program be
installed on your computer. You can generally download free
versions or trial versions of unzipping software such as PKZIP®
or WinZip® for Windows. If you are using PKZIP, once you
have located the file dairy.zip, right click on it once with
your mouse and then select extract to. Your unzipping
software should then open. Navigate to a directory in which
you want to save your unzipped files, and then click extract.
A window will appear when the extraction is complete; click
Done.
Close PKZIP for Windows.
The Interchange (.e00) file for 2002 Washington State dairy
sites is now ready to be imported for use in ArcView 8.x.
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Importing
Interchange (.e00) Files
Now that you have successfully downloaded the Interchange (.e00)
file for 2002 Washington State dairy sites, it is time to import
the file using ArcToolbox®. This import process will convert
the Interchange file into an ArcInfo® coverage that can
be used in ArcView applications such as ArcMap®.
Start by opening ArcToolbox
and expanding the Conversion Tools list. Now expand the Import
to Coverage list and double-click on ArcView
Import from Interchange File.
Specify the file that is to be imported by clicking on the
folder icon next to the Input
file and navigating to the directory in which you saved
the dairy.e00 file.
After locating the dairy.e00 file, click on it once, and then
click the Open button.
Your input file (e.g., dairy.e00) has now been specified and
the dialog should look similar to the one represented below.
Now specify the directory in which you would like the Interchange
(.e00) file to be imported. Do this by clicking on the folder
icon next to Output dataset and navigating to the directory
in which you want to save the file. Give the file a new name
by typing dairy_2002 next
to Name. Make sure the Save as type option is set to Coverages
as seen in the dialog below. Click the Save
button.
You should now see a dialog similar to the one represented
below.
Click OK to finish the
importing process. You have just converted your Interchange
(.e00) file to an ArcInfo® coverage that can now be used
in ArcView applications, such as ArcMap®.
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