M@IN - Accessing Spatial Data Tutorial
NSDI - Clearinghouse Example Sites
This page contains links to some sample Clearinghouse nodes on the Internet. Since each site
contains quite of bit of information, a listing of suggested steps is given to show some basic
Downloading and printing (or writing) this page is helpful when going through these examples.
Use the "Back" button on your web browser to
come back to this page when your done viewing a site, or use the browser to go to
Clearinghouses vary in complexity and type of searches which can be performed, but the goal is to tell potential users what geographic data is available from a particular site. Below are a couple of examples of Clearinghouses and their functionality. We just looked at the basic search types the NCGDC offers, and more specific information about the NCGDC will be seen on page 12 of this tutorial when some search examples are given.
The first site is a good example of a basic Clearinghouse node. At the homepage there are links to background and GIS specific information and a direct link to Spatial Data. Selecting the Spatial Data box, brings up a page which allows
selection by Theme, Scale, or Sources. Since not all the data being described on this server has metadata yet, try this: (remember to use the "back" button to return to this page),
- Go to the site below.
- Select Spatial Data.
- Select Scales.
- Select 1:100,000 from the left hand margin.
- In the right hand window you'll see a table with a column "Documentation".
Scroll down until FGDC appears in the column.
- Select FGDC.
- This brings up the metadata.
- Hit the "Back" button a number of times to return to this page.
Oregon - State Service Center for Geographic Information Systems, Salem, Oregon.
This next example is the US Federal Government Clearinghouse Gateway. This enables custom searching of many clearinghouse nodes (including North Carolina), by allowing a user to input the search parameters and query multiple databases at one time. This is done by searching indexes of metadata.
National Geospatial Data Clearinghouse Gateway, FGDC Node, Reston, Virginia.
- Go the the site below (sometimes its slow).
- Select the Connect to Service Button.
- The form you see next can be filled in to pose a search.
- Look at all the options, use only these few to try a search.
- Scroll to "Keyword & Fielded Search".
- In the first "Text Input" box type in water.
- Scroll down to "Databases".
- We want to select the North Carolina Corporate Geographic Database only. Depending on which browser you are using, you will need to unselect the default setting in different ways. Select on the database below the highlighted one. If it becomes highlighted also, you will need to click both again to unselect them. If, however, you select the second one and the first one becomes unselected, just go to the next step in this list.
- Scroll down the list and "click" once with your mouse on North Carolina Corporate Geographic Database.
- Scroll down and select the Submit Query box.
- Names of geospatial metadata files in the NC database which match this search will be presented.
- Select one from the list to view the metadata (More on this record).
- Use the back button to get back to this page.
Now that we've seen a couple of Clearinghouses in other parts of the county, let's take a look at how the North Carolina Geographic Data Clearinghouse works.
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