Poor Man’s GPS

– Posted in: Miscellaneous, Recommended Links
1 comment

Almost a month ago, when the first snow was predicted for the “higher elevations,” I got a hankering to know exactly how high we are here in Purdyville. The easiest way, of course, is to get out your handy-dandy GPS (Global Positioning System) and take a reading. Alas, I don’t own one of these fascinating gadgets. The old-fashioned way is to check your location on a topographical map. As it happens, we do own one of these, but it’s not as accurate as I would like. First of all, I find it difficult to pinpoint my house’s exact location on the map. (This isn’t as much of a problem in more densely populated areas.) And the lines that mark elevation are too close together for a precise reading.

My brother came to the rescue and made me aware of the National Map Viewer. This is a government site (your tax dollars at work) that coordinates maps from several different government agencies and allows them to be displayed in layers for any particular location in the U. S. you might fancy.

The fastest way to get your elevation is to click the Find Place icon on the left side of the map. Type in your address and click Zoom to Address. If, like me, you find this map rather featureless, go to the right side of the map and click on Orthoimagery, specifically TerraServer USA DOQ, and then click on the Refresh Required button. If the website isn’t too busy, that will bring up a satellite image of the area and make it easier for you to pick out landmarks. Next, click on the Elevation tool on the left, and then click on the exact spot on the map that you want the elevation of. A new window will open which gives you the latitude, longitude, and elevation for the place on the map that you clicked on. Trust me, that took longer for me to explain than it will take for you to do.

Okay, that’s the fastest way to get the info, but I don’t think it’s the most accurate. I think it works better if you use the Acme Mapper to establish your longitude and latitude first, and then use the National Map Viewer to get your elevation. The Acme Mapper has been around a lot longer (in internet-years) than Google maps and related Google services, and it still is quite useful. It uses the same TerraServer maps as the National Map Viewer, and it lets you zoom in closer. This is why I think I get a more accurate longitude and latitude this way. Just type your address in the Find box below the default map. When it brings up your location, switch the Theme to Image and the Scale to 1 m/p (meters per pixel). There should be a red marker visible marking the address you typed in. If it’s placed accurately, scroll down to the bottom of the page for your latitude and longitude. If it’s not placed accurately, click the spot that really marks the location, and then scroll down for the coordinates. As you can see, there are several other map-related links you can click at the bottom of the page, all of them fascinating.

So, with the longitude and latitude that you got from Acme Mapper, go back to the National Map Viewer, and enter the coordinates into Find Place. With your location pinpointed, use the Elevation tool to find your elevation above sea level. How much did it differ from the first method?

There are a lot of fun things you can do with maps these days, but most of them are more satisfying if you know your coordinates. I’ve detailed one way of finding your coordinates without using any fancy gadgetry. If you know of another internet source for finding your geographic coordinates, or if you know of other websites or applets of interest to gardeners, please let us all know in the comments.

About the Author

Kathy Purdy is a colchicum evangelist, converting unsuspecting gardeners into colchicophiles. She would be delighted to speak to your group about colchicums or other gardening topics. Kathy’s been writing since 4th grade, gardening since high school, and blogging since 2002.

Autumn is a second spring when every leaf is a flower.

~Albert Camus in Albert Camus quotations

Comments on this entry are closed.

cyndy December 5, 2005, 1:24 pm

Thanks Kathy! These are very useful links…I plan to check them out when I get some time…they sound very informative.