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11 — My favorite use for the Global Positioning System (GPS).

2015-03-15. By Patrick.

When we go hiking, we sometimes take a trail GPS along. Sometimes, we stick it in the top of one of our backpacks and forget about it until we get back. Sometimes, I keep it in a pocket where I can quickly pull it out, hit the "save waypoint" button, and put it away. We never bring up the map, or the coordinates, or any other information on the GPS unit while we're hiking. Personally, I don't think it's an evil thing to do so. It's just a question of style. I read about this way of using a GPS unit while on hikes somewhere on the web, I think. I don't remember. If you recognize your idea, thank you for a fantastic system.

So what's the point of using the GPS like this? And first of all, why not use it to find your way? I like to use map and compass. And sometimes I like to follow contour lines using an altimeter. And I like to do radio direction finding in the woods. So it's not like don't like technology in the wild. I'm not sure. Maybe a comparison with a car GPS unit can shed light. We use a car GPS unit all the time. And it's a wonderful thing. We just talk as the GPS periodically reminds us to take the next turn. Most of the time, I can barely remember the route we took when we used the car GPS. That's not good but whatever. I don't care that much. Maybe others have a different experience. The point is, with the car GPS we don't have to pay attention to our environment. With a trail GPS, you certainly don't have to either. You just follow the direction in which it tells you to go. Or I guess that's how people use it. When I'm out in the woods, a large part of the fun is reading the land. The uncertainty is all part of the adventure.

So, why use the trail GPS at all? Well, it's when we get home. And this part gets pretty involved.

First I find a map of the area we were in. Preferably a topographic map with a scale of 1:25,000 or 1:24,000. This last year it's been more 1:10,000 because we've been doing so much orienteering instead of hiking. If it's paper, we scan it into the computer. Thank you goes to the developers of sane and xsane. Or maybe we find it on the web. The USGS site is a good place. Although I detest the move to the putting all data on these complicated PDFs that I can't open and that contain tons of data for which I have no use. I just don't understand why people make things so complicated. Just let us download the layers in well established formats that can be easily handled by most software instead of requiring us to download all the information and use format that's so much work to figure out. Anyway...

Then we need to find a way to georeference the map image. Sometimes the maps have coordinates directly on them. If we took some waypoints at positions that are precisely known on the map, we can use those. If we can recognize some places in Google Maps, clicking on them will give the latitude and longitude. Some of these systems are more accurate than others but I'm usually not too worried about accuracy. If I know our position within 30 meters, I already have more accuracy than I usually need.

The final part is actually creating the georeferenced map image and plotting our track and waypoints on it. That's where QLandkarteGT comes in. And a _huge_ thanks goes to the developers at Qlandkarte. In particular, Oliver Eichler is listed in QLandkarte's "About" window. QLandkarte has an easy system for georeferencing a map image. First a TIFF can be loaded and marked at several points with coordinates. Then QLandkarte does some processing and a 'geo-TIFF' is saved.

To see our track on the map, we simply load the geo-TIFF into QLandkarte. We then download the data from the GPS unit and import it into QLandkarte; or have QLandkarte download it directly from the GPS unit via a USB cable. And there are the waypoints and tracks superimposed on the map. We can change symbols and colors and cut tracks and do all sorts of things. Usually, I'll end by taking several images of the map with info superimposed and saving them in a folder where I keep documentation about that outing. Usually I'll use Gimp to add stuff to the map: text here and there about what we did, a picture with an arrow to the position where we took it, a colored in contour line to emphasize some elevation change.

Many times, we'll bring them up and look at them while we plan future events. But mostly it's just fun to go over these images later in the year.

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