Tuesday, April 27, 2010

GPS Tracks and Maps

Dave and I have been having some interesting discussions about handheld GPS units. I have become addicted to geocaching, as per my last couple of posts, and a few challenges from an old friend. Side question - is it mean to issue challenges to a compulsive personality?

Anyway, I spent $160 on a Garmin eTrex Venture HC bundle that included 100k topographic maps, which while not USGS hiker quality, are pretty good, and fun to play around with. This is a good solid (but relatively speaking low-end) unit that at this point does most of what I need it to do - point me at geocaches and record my trips. Dave did some digging around and came up with gpsvisualizer.com, a free website that will take a .gpx track file from a GPS and turn it into a track on a map.

The map below is the track of the geocaching trip that the girls and I took in Darlington Park this past weekend, and is immortalized below. Our track is the faint green line starting on Darlington Road, crossing under the railroad tracks, winding through the countryside, and returning. This is the functionality that makes Dave all tingly, and is possible with the out-of-the-box GPS and a few free websites and free software downloads. The below jpeg is the track overlaid over a USGS topo map.

The next pic is the same track overlaid over a black and white USGS aerial photo.

Note that in both maps, the majority of the track is in bright green, as we were at the lowest elevation along the creek. As the elevation increases, the color of the track changes through blue to purple. About halfway through the green track, you can see the minor detour off the trail we made to get the first cache, and later you can see the wrong trail we took before doubling back and going furthest to the right to get the last cache toward the top of the hill.

Unfortunately, the coolest overlay that you can do on the website (but not save as a jpeg) is to overlay the track on a Google satellite photo.

The application of this to a real hike, however modest, makes me drool. The GPS already records the distance travelled, the route and the elevation profile of the entire trip; these other free software downloads and websites turn that data into a trip map.

Amazing stuff...
[Updated 5/23/2010]: Now that I know how to make nicer maps, the below is a revised map of our hike with the two cache locations marked as black squares.

1 comment:

  1. Yeah, you got me. You should ask Garmin for a commission on the unit I will surely be buying. I will *not* be doing another major (or maybe even minor) hike without this.

    And I'm also excited about geocaching. I was looking at the caches in some of my favorite places (French Creek, Marsh Creek, the A.T. around Port Clinton, Turner's Creek), and I think it would be a lot of fun to do some geocaching there. Also hopeful, as you are, that my girls might enjoy it.