With If purchasing EDX Cirrus high-resolution data tiles, with access to large terrain and clutter datasets, or purchasing EDX Cirrus high-resolution data, determine determining the smallest number of tiles you need for a project can be confusing. This article aims to demystify tile naming practices and help determining how to easily find the number of tiles needed tiles easily.
EDX packages terrain and clutter data by square degree. It is usually named using the following convention: long_lat_resolution.extension. For example, a 10m Cirrus terrain file might be named 123w43n_10m.pte.
Cirrus 5m and 1m clutter is further sub-divided into 16 sub-tiles for each square degree. A representative Cirrus clutter sub-tile would be named 124w44n_r4_c4_us1m_ds5.gce.
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Open your map layers and highlight the Reference Grid layer, then click the Style button to display the following dialog box.
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Ensure the grid spacing is set to 1 degree, then click OK. Make sure the reference grid layer is above any bing Bing map or extracted terrain/clutter layers. Click OK to exit back to the main map window.
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Zoom out until you can easily see the reference grid lines. You can pan the map until you’re in your area of interest. In the example below, say we’re interested in data for the Eugene/Springfield area. Notice how Eugene/Springfield is covered by at least 2 tiles, possibly 4 if we want to cover down through pleasant hillPleasant Hill.
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To find the latitude and longitude, look in lower right of the status bar to see the coordinates. For example, if I put the mouse cursor is placed on Eugene, it reports 44.049955n, -123.107221. Ignore the decimals, and you’re looking at tile -123w44n.
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