Tuesday, 5 August 2008

USGS Free Maps

The word 'free' drew me in as I read the newsfeed from The Goat. Maps and free. Great combo. The fact that I had never been to America was beside the point, and a trip to the U.S. Geological Survey was called for.

Direct links time out, so a bit of navigation was needed. Then off to Sharpsburg, but finding one in Georgia instead, I still sampled the topothingamy maps via their map locator. They cover some of Canada too (maybe for the invasion).

Once you zoom in enough to an area you are interested in, you can download a map and view it in Adobe's PDF Reader. There's an additional toolbar that you can download, adding more functionality, and the ability to link back into Google Maps.

With the cursor, you can get accurate WGS 84 Lon/Lat readings. As well as measuring areas and lengths (the Paradise Lakes are about 3,152 feet long), magnetic bearings are given. That could be a useful feature for trekking by compass. Remember to add, or is it subtract, the variation.

If, like me, a GPS unit is the main navigation tool after a map, there is GPS support and a lot of information in the help file.

I don't know if this is the level of detail for maps in the USA, or if there is something approaching what our own Ordnance Survey produces. Right enough, though, the 1:24,000 map that I'm looking at was last revised in 1982. I'll need a closer look at some places. Upstate New England I think.