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Topo Maps, an application from Philip Endecott, is available for US$7.99 cents at the App Store.
If you're driving around on pavement in the United States, chances are you're often within cellular service, which means you can use Google (Nasdaq: GOOG) Maps and Google Earth, along with your iPhone's built-in GPS feature, to pinpoint your location and find your way.
The problem with Google Maps and Google Earth is that you really need to have access to a compatible cellular service tower that can handle data for these apps to work well. If you're off the beaten track without cell service, your iPhone can't download the maps.
No maps, and that little blue GPS location dot doesn't mean much.
Enter Topo Maps
While you can let Google Earth, for example, store map data in cache, it's not exactly predictable or reliable. If you're hitting a remote trail, you really ought to have a static topo map, loaded into your phone, that you can access any time you have enough battery power to run your iPhone. There are a few options available in the Apple (Nasdaq: AAPL) App Store, but the one I use and appreciate most is the excellent Topo Maps.
It's got a solid -- but not cluttered -- set of mapping features that is based on United States Geological Survey (USGS) topo maps. These kinds of maps show contour lines that tell you shapes of mountains and canyons, and show you roads, trails, rivers and lakes, as well as forested or barren landscapes. They typically have a scale of 1:24,000. The nice thing about USGS maps is that they offer pretty consistent coverage across the U.S., and I don't believe they require any sort of licensing to use, which means that app developers can take these maps, scan them at high resolutions, and then integrate them with GPS locations and build applications for the iPhone, for example, around them.
On the downside, many of these maps might be decades old, created or last updated in the 1980s. Obviously roads, trails, and waterways can change after 30 years.
In some cases, for example, GPS-focused companies that make dedicated outdoor GPS devices have access to higher-quality maps than what you'll get out of USGS topo maps, but you can guess why they don't want to offer inexpensive iPhone options -- who would buy expensive dedicated GPS units then?
So, for $7.99 and an iPhone, Topo Maps works surprisingly well.
How to Use Topo Maps
To get started, you'll have to download a map. To do this, you first look at a satellite view of the U.S. If you zoom in, you'll get closer to the ground and you'll start to see overlay detail like state lines, cities, and points of interest. Keep zooming in, and you'll see a grid of green squares. Tap and hold your finger on any of these green squares and upon release, you'll be prompted to download a map for the area. You can choose a low or high-resolution map, and the only time you'd want to bother with a lower-resolution option is if you've got a funky data signal and you need to get the map downloaded fast. For the most part, though, you'll end up downloading the maps you want, in advance of your outdoor getaway, from the comfort of a strong signal or WiFi connection.
Once you download a map, the green-lined grid will show the square that has the map as a translucent green fill. Tap on a filled green square, and you'll load the map. You can navigate it with all of the usually gestures -- pinching for zooming, flicking or dragging for movement.
Enter the GPS
Of course, the map itself is handy, and it'll work with an iPod touch, but the real key is the built-in GPS features. Tap the overlaid button of a circle with the target marks, and the GPS will pinpoint your location with the familiar glowing blue dot. The dot also includes a blue circle around it to show you the likely accuracy of your fix. In my experience, my position on the map has been very close -- within a few feet -- of my position on the world itself. Accuracy diminishes in heavy forest or canyons, of course.
Last summer, Topo Maps saved me and some friends from an exhausting mistake. We were backpacking uphill to a mountain lake, and the trail was mismarked so that a fork in the trail appeared to be the right way to go. After a half-mile or so heading steeply downhill, our trail hit a really old logging road and disappeared. We found what appeared to be the rest of the trail, but at this point, we were dubious that it was heading anywhere high enough to take us to the lake. And yet, the prospect of climbing back the way we came with a backpack full of gear in the heat of the day wasn't much appealing.
I had a paper map, of course, but it was hard to pinpoint our location because the trail we were supposedly on was not likely the trail on the map. That's when I pulled out my trusty iPhone 3G and fired up Topo Maps. Sure enough, the blue dot didn't lie -- we were closer to the lake, but we would have to bushwhack our way through heavy brush and fallen timber to get to it. Ultimately, we hiked back the way we came -- and found the lake.
Like it is with any map, or even with dedicated GPS devices, you've got to trust the real landscape right in front of you -- you can't depend on a GPS unit or map to save you from truly getting lost. In any remote situation, Topo Maps should be used with a healthy dose of common sense -- and outdoor experience, really.
Extra Features
Beyond the basics, Topo Maps has also evolved to add waypoints that you can add to your maps, and it even lets you download waypoint files from the Internet. The map settings controls let you choose slope shading so that you can replicate the position of the sun -- cool -- as well as set height shading so that high peaks appear brown, for example.
You can figure out distance on a topo map by understanding the distance between the contour lines, but that can be tough or time consuming. A distance button generates concentric circles that show you the distance in kilometers, miles, or feet from a center position on a map. Bearings can be shown in degrees or mils, if you're so inclined to care.
Interestingly, Topo Maps sports a visibility mode that computes what you can theoretically see from a location on the map. If you choose a position deep in a canyon, you'll have visibility down to feet. If you choose a mountain top, visibility shoots out to miles -- and the deep spaces in canyons would remain out of sight.
While most users can figure out the basics in Topo Maps by playing around with it, topomapsapp.com has a quick start-guide, as well as a detailed user guide. And if you've got an iPad, there's a big-screen version, too.
One last thing: While Topo Maps works on the iPhone 4, it's not working 100 percent correctly. Because the iPhone 4 sports a high-resolution screen, when you zoom far into a map, it shows you a 4-tiled replicated view of an area. If you zoom out a bit, the view will return to normal. The developer says he's working on an update.
In the meantime, even with the glitch, using Topo Maps on iPhone 4 is a step up from my old iPhone 3G -- the Retina Display really improves the overall look of the maps. And yes, if you spend any time off the beaten path -- and are not inclined to buy a dedicated, robust GPS unit -- shell out $7.99 for the app. You won't regret it. Just pack a few sandwich bags to slip your iPhone into in case it rains -- and don't drop it in the mud or on the rocks.
