Free Geography Tools

Google Earth Library posts on a new service from the USGS that lets you download 1:24K, 1:100K and 1:250K topo maps for anywhere in the US in GeoPDF format. It has an easy-to-use interface based on Google Maps that makes finding your location, and downloading the desired maps in compressed zip format, straightforward.

First, if you don’t already have it, you should download and install the GeoPDF plug-in for Acrobat Reader. While you’ll be able to open the maps as regular PDF files without the plug-in, it adds some very useful geographic capabilities to Acrobat Reader. Plus then, Acrobat Reader won’t bug you about downloading the plug-in every time you open a GeoPDF file.

The USGS Store - Map Locator & Downloader is available at a link from this page; it also may be directly available at this link, but the latter looks suspiciously like a temporary link. Once there, use the standard Google Maps controls to zoom in to the area you’re interested in (click on the image for a larger view):

Click on the “Mark Points on Map” radio button on the right, and then click on a location on the map that you’d like to see the available maps for:

Click on the marker, and an information bubble will appear with a list of available maps for the marker area, and links to order the maps from the USGS or download them directly:

Click on a download link, and a zipped copy of the map in GeoPDF file will be immediately downloaded to your computer, about 5 MB in size.

If you open the GeoPDF file in Acrobat Reader after installing the GeoPDF plug-in, the geographic coordinates of your cursor position can be seen in the lower right. You’ll also see the GeoPDF toolbar at the upper left:

GeoTool: Let’s you mark a position on the map with a click, and freezes that position in the coordinate display. Click again to remove the marker.

GeoLocator: Displays the coordinates of the cursor, and freezes them when you click on the map; when you click on “GO”, it will zoom in on that arrow. Click on the arrow, and you can change the map projection (Geographic, UTM, SPCS, USNG, etc.), the datum (WGS84, NAD27, etc.), and the units (meters, feet, survey feet). Very handy.

GeoMeasure: Lets you measure distance and area on the map. Click once on the map to enter a point; double-click to end a line for distance, or to close a polygon for area.

GeoTrack: Lets you track your position with a GPS (requires a serial connection, and probably NMEA; wasn’t able to test this).