
[-defdefine LessonName "Using the USGS Seamless Map Data Server"-]
<section id='BaseOps_Tutorial_USGS_SeamlessMapDataServer_id'>
    [-include "BaseOps_SetUpStandardWorkbookCase.tutscript"-]
    <title>
        &LessonName;
    </title>
    <section>
        <title>
            &LessonName;
        </title>
        <para>
            The United States Geological Survey (USGS) runs a website that
            provides access to large amounts of map data. This site, the Seamless
            Map Data Server, allows you to indicate your area of interest
            and desired type of map data. The data server will then query
            the USGS database, extract the requested data, and provide you
            with a download link.
        </para>
        <para>
            This lesson will teach you how to use the seamless data server.
            It is presented as a list of step-by-step instructions. To begin,
            press the <bold>First Step</bold> button below.
        </para>
    </section>
    <section>
        <title>
            Step 1
        </title>
        <para>
            In this tutorial example, we will assume that you wish to download
            National Elevation Dataset (NED) elevation data for use in your
            BaseOps case. We will assume that your site is located in the
            continental United States.
        </para>
        <para>
            Using your web browser, access the seamless server at <link>http://seamless.usgs.gov</link>.
            The seamless web server portal page will appear.
        </para>
        <exhibit>
            <img
            src='BaseOps_ElevationChunk_SeamlessMapServer_PortalPage_ScreenCap.png'/>
        </exhibit>
        <para>
            Click on "View &amp; Download United States Data".
        </para>
        <note type='tip'>
            <para>
                The seamless data server web site can be quite sluggish, even
                if you have a fast internet connection. After clicking a link
                or performing an operation, it can be many seconds before the
                site responds. Work slowly, and give the site ample time to respond.
            </para>
        </note>
    </section>
    <section>
        <title>
            Step 2
        </title>
        <para>
            You must first choose the type of data that you wish to download.
            Click on the Download tab (located near the right edge of the
            browser window). Then, open the Elevation section and check the
            box next to 1" NED.
        </para>
        <para>
            [-include "BaseOps_ShowMeHowLink.rxl" VideoName='BaseOps_ElevationChunk_SeamlessMapServer_Video - 1.wcsaf'-]
        </para>
        <note type='note'>
            <para>
                If, instead of NED elevation data, you were downloading National
                Land Cover Dataset (NLCD) 2001 ground cover data, you would open
                the Land Cover section and check the NLCD 2001 Land Cover box.
            </para>
        </note>
    </section>
    <section>
        <title>
            Step 3
        </title>
        <para>
            Select the Zoom tool by clicking on the magnifying glass toolbar
            button. Then, use the tool to zoom in so that you can clearly
            see your area of interest. Using the tool, drag a rectangle on
            the map. The rectangular area will then expand to fill the map
            area.
        </para>
        <para>
            [-include "BaseOps_ShowMeHowLink.rxl" VideoName='BaseOps_ElevationChunk_SeamlessMapServer_Video - 2.wcsaf'-]
        </para>
    </section>
    <section>
        <title>
            Step 4
        </title>
        <para>
            Select the "Define Rectangular Download Area" tool by clicking
            on the dotted rectangle and arrow toolbar button. Then, drag a
            rectangle that encloses your area of interest (i.e., the portion
            of the earth's surface covered by the elevation data that you
            wish to download).
        </para>
        <para>
            [-include "BaseOps_ShowMeHowLink.rxl" VideoName='BaseOps_ElevationChunk_SeamlessMapServer_Video - 3.wcsaf'-]
        </para>
        <para>
            The Request Summary Page appears, listing the map data you have
            selected.
        </para>
    </section>
    <section>
        <title>
            Step 5
        </title>
        <para>
            You must now choose the format of the map data you will download.
            BaseOps imports NED elevation data in the GridFloat format, so
            you must tell the seamless data server to provide the data in
            that format.
        </para>
        <para>
            Click on the Modify Data Request link. A list will appear, indicating
            all of the data products available for the area you have selected.
            Scroll down to the Elevation section.
        </para>
        <para>
            Note that each data product is followed by three dropdown list
            controls. The first control allows you to select the download
            data format. For the row labeled "National Elevation Dataset (NED)
            1 Arc Second", select GridFloat for the format.
        </para>
        <para>
            The other two columns of dropdown controls allow you to select
            the compression method and the metadata format for the downloaded
            data. It is recommended that you leave these set to the default
            values of "ZIP" and "HTML".
        </para>
        <para>
            [-include "BaseOps_ShowMeHowLink.rxl" VideoName='BaseOps_ElevationChunk_SeamlessMapServer_Video - 4.wcsaf'-]
        </para>
        <note type='note'>
            <para>
                If, instead of NED elevation data, you were downloading National
                Land Cover Dataset (NLCD) 2001 ground cover data, you would go
                to the "National Land Cover Dataset 2001 - Land Cover" row in
                the "Land Cover" section, and select "BIL" for the download format.
            </para>
        </note>
    </section>
    <section>
        <title>
            Step 6
        </title>
        <para>
            Scroll to the bottom of the page, and click the "Save Changes
            &amp; Return to Summary" button. You will be taken back to the
            Request Summary Page.
        </para>
        <para>
            Click on the Download button. The seamless data server will query
            its database, extract the elevation data you requested, and compress
            it into a ZIP file.
        </para>
        <note type='note'>
            <para>
                It can take several minutes for the seamless data server to extract
                the requested data and construct the ZIP file.
            </para>
        </note>
        <para>
            [-include "BaseOps_ShowMeHowLink.rxl" VideoName='BaseOps_ElevationChunk_SeamlessMapServer_Video - 5.wcsaf'-]
        </para>
        <para>
            The ZIP file will then begin downloading to your computer.
        </para>
        <para>
            Once the ZIP file has finished downloading, you can unzip it using
            a tool such as WinZip, and import the data into BaseOps. See the
            BaseOps Users' Guide for information on importing elevation data.
        </para>
    </section>
</section>
