Using digital maps/navigation in backcountry?

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JWreno
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Re: Using digital maps/navigation in backcountry?

Post by JWreno » Fri May 05, 2017 10:30 am

I currently carry a Suntastic solar panel on my pack lid to charge my iPhone, Steripens, camera batteries, flashlight batteries and GPS batteries if I have one for trips longer than a few days. Since I am usually backpacking with my wife and son I can justify the weight of the solar verses carrying more batteries. We use 3 usb charged Steripens and recharge them about every 5 or so days. The phone provides useful navigation, occasional phone calls when closer to cell sites, entertainment with music, games and downloaded books to read. It is easy to recharge with the solar panel.

I like to carry a paper map of my planned route. I also have a compass. I like to preload topographic maps for all of the Sierras on a app for my phone. The maps are useful for times when I may deviate from the planned route. I also want the maps for those times when I am just out day hiking and my not happy prepared by printing and packing a larger map.

My Garmin can show maps but the interface and screen size don't compare to the quality of the displayed maps on my iPhone. I only carry the Garmin for those times when I plan not to be following a regular trail. Eventually I may only use the iPhone, paper maps and compass and leave the Garmin at home. I think the option to add satellite imagery to the topo maps can really help to understand more about the terrain. I would love to have an offline Google Earth like app that I could use on my phone without Internet access. I love using Google Earth at home to fly through areas I have hiked or would like to.

Last year we spent five days off trail and the GPS or iPhone was a useful confirmation of our current location on the map. I have had other times backpacking or day hiking when we didn't pay attention and ended up in places other than planed. The map and compass were very useful for plotting a route to get back to where we intended to be.

I learned my basic map and compass navigation skills as part of becoming an Eagle scout. I grew up in Michigan and didn't appreciate the affects of topography on navigation until I move to Reno and started hiking in the Sierras back in the 90's. There are several times when we thought we could shortcut some trail miles by route finding over a pass. Sometimes successful but other times we had to turn back when the topography became impossible to cross.
Jeff

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Re: Using digital maps/navigation in backcountry?

Post by gdurkee » Mon Jun 05, 2017 8:56 am

All:

Sorry I've not weighed in. After I posted this I guess my HST notification of replies is glitched, then I forgot about the post... .

Anyway, thanks for all the comments and suggestions! I of course agree that paper maps need to be the basis/foundation of all b/c navigation. What I'm starting to look at is how to integrate gizmos and digital maps into navigation and location needs.

In my post, the first thought I had (for the public) was for the Horizon Ridge Ski Trail into Ostrander Hut. This might be a good test case. Many people coming in are routinely coming in well after dark. The trail is marked by reflective metal signs but there are some gaps where, about once a week, skiers miss the trail and wander off making a difficult night even worse. I was considering both a print map with critical navigational waypoints labeled with lat/long and a digital map such that a person could follow a trail on their phone as well as GO TO any of the waypoints or the Hut.

A number of you mentioned being hampered in navigation by fog. Whiteouts in winter are a similar case and, really, worse. I've practiced navigating back to the Hut in storms -- setting it as a waypoint in high winds, horizontal snow, hood over me and just following the directional arrow. Worked great. A paper map would have been difficult to impossible (no landmarks, trying to hold it in high winds, getting it oriented to put a compass on it etc....). Years ago, 4 of us were in a whiteout on Bishop Pass with about 10' visibility. After stumbling on the Bishop Pass sign, we did navigate with a map and cheap compass to the descent route (not the same as the trail) about 1/2 mile away. One of us would go out about 10' and be waved left or right to stay on the compass course, Took about two hours to get to the descent gully. It did work but, in -20F and 30+mph winds, a gps would have been more efficient and faster. So it is possible to use a paper map in those conditions, but our experience level was a minimum of 20 years on skis each.

The other advantage beyond mere navigation is the ability to layer other data for customized digital maps or, even, update the USGS Topos which are mostly all well out of date -- last editions for the Sierra are in the 80s. Another story? OK! Years ago (and everything is years ago now...) a friend was coming in to visit me at Rock Creek Ranger Station. I waited at Chicken Spring Lake but he didn't show. I eventually went back to the RS and he appeared two days later. Turns out he was looking at the topo from the 50s, saw the trailhead down at the bottom -- before the road to Horseshoe was built!! -- and hiked up that, getting to Horseshoe and hearing cars. Oooops.

So for rangers in Yosemite, we're loading customized data onto phones and tablets showing locations of trails, roads, fire hydrants, pay phones (to respond to 911 calls from them), all buildings with addresses labeled & etc. There are also likely situations where the average hiker/backcountry user might want different data than is offered by a static USGS Topo. A number of you also mentioned creating your own maps and printing them, which is really useful. It's only one more step to add them to a phone or something.

Finally (well, for the moment), GPS and phones can offer a more accurate location when reporting an emergency or even just a feature or camp. You can, of course, do that on a paper map but with actual USGS Topos, you've got only the choice of UTM or DMS and they'll be in NAD27. Unless you've got a plastic template, getting accuracy below 1/10th of a mile or so is difficult. There's about 1/4 mile difference on a N/S axis between NAD27 and NAD83 or WGS84. (As a side note, there's all sorts of errors that can creep into obtaining location coordinates with a phone. Maybe I'll do that as a separate post).

Anyway, I think there's a specific set of uses for digital maps in the backcountry -- and probably more for frontcountry recreational users. So called "story maps" are coming into use where you can load a specific trail with natural history/self guided information onto it. Maybe having cool geologic or national history features for the JMT or Rae Lakes loop would be useful for some. Another side note: James Moore in Exploring the Highest Sierra has a great 'geologic features of the JMT & HST but the book's a bit hefty to take along as a field guide. Worth reading though!

OK. Thoughts and further suggestions welcome! Thanks!

George

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rlown
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Re: Using digital maps/navigation in backcountry?

Post by rlown » Mon Jun 05, 2017 10:47 am

For rangers in Yosemite, the cell coverage on the East end of the park is spotty at best, but I get the GPS part.. Guess they still have to carry the radio as well.

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Re: Using digital maps/navigation in backcountry?

Post by gdurkee » Mon Jun 05, 2017 11:14 am

OK. By popular demand (well, none, really) here's a few words about the location errors that can be inherent in both GPS devices and, especially, phones. As probably most of you know, a GPS is a passive receiver that gets a signal from a set of satellites. It then calculates the time the signal left the satellite and was sensed by the gps to give a position on the surface of the earth (as well as a value for elevation...). The minimum for an accurate 3D fix is getting signals from at least 3 satellites though you can get XY coordinates from 2. Each GPS must have a current table of satellite locations to make that calculation (called an Almanac). Because of the restricted bandwidth available to GPS, it takes about 20 minutes to download the Almanac. This needs to be done every week or two. If you've not turned on your GPS in awhile or moved more than about 50 miles from your last fix, it might take up to 20 minutes to obtain a valid location. This applies to the GPS on dedicated devices and to phones. (There's another file that's required -- ephemeris data, which is more local to the gps' area, but let's skip that...).

So, the first error for pure GPS location with both phones and dedicated gps devices is the time it takes to acquire a location from a "cold start" or long delay or having moved a distance since the last start. The semi-good news is, on dedicated GPS, you won't get position coordinates until it's got a current almanac and a couple of satellite signals. The main error in coordinates show is going to be from what's called "multi-path" signals from the satellite. Since the gps calculations are dependent on time of satellite signal to device, if that signal bounces off a cliff, a car, building etc., it takes longer and the coordinate shown won't be accurate. I've seen errors of as much of a mile in narrow canyons where the signal is bouncing all over the place. One partial solution is to stay in one place for awhile and see where points coalesce -- that's probably your actual location.

Next: phones. These are way more complicated and can have a lot of errors. In SAR, we've gotten locations reported from people in trouble reading off their cell phone. Distances from actual location have been up to 4 miles off and responders have often gone to the wrong place. Researching how such errors happens is what sucked me into learning about this stuff.

Anyway, sources for error are:

1) Just reporting coordinates in a way that the person receiving misunderstands. This applies to both dedicated GPS and phones. You MUST identify the coordinate type (decimal degrees, degrees minutes seconds etc.), clearly read the numbers individually and be sure to identify separators such as "degrees", "minutes", "seconds", "point" for the decimal, "East or West" for longitude (or "minus"). Don't let a pause substitute for those identifiers -- e.g. "thirty-six" pause "sixteen" pause "forty" where the pause should be degrees, minutes, seconds. Sorry to drive this into the ground but, in SAR, this is a huge problem. And identify the Datum --especially if reading from a paper USGS map. When getting coordinates from someone, be sure to ask or confirm coordinate type and Datum. Lots and lots and lots of errors in emergency response because people mess this basic stuff up.

2) Phones: manufacturers take shortcuts to obtain location more quickly. They'll calculate distance from the cell tower (which includes location data in its signal); they'll use known wifi locations (this is what the Google Mobile and other data collection does); and use the phone's built in GPS Here's the problems.

Pure GPS/satellite signal is going to be the most accurate, but not the fasted. Averaging anything else into the location shown will cause errors. If you have only one tower available (the case in many rural areas), you just get an estimate based on the time calculated for the round trip distance to the tower averaged with the gps first guess. Some phones (iPhones especially) will show only the last good fix it's held in a cache, which could be miles away.

Phones will also take a shortcut in not requiring a full current Almanac. Newer phones can download an Almanac (A-GPS or Assisted GPS) more quickly off the nearest tower which might help. You still, though, get the errors in averaging of whatever settings you're using.

Now, with an Android, you can actually set it to GPS only. The other settings (e.g. Battery or Power Saving) turns off GPS and gives you the worst results. "High accuracy" is really only medium accuracy since it forces the phone to average cell tower with gps and, if available, any wifi in the area.

With an iPhone you're out of luck. There's no way to force GPS only -- though maybe turn off wifi and cell, leaving only gps on?? I don't know -- don't have an iPhone.

A friend -- Joseph Elfelt -- who helped me understand this stuff has developed an app that, if you have a cell data connection, will show your location and the estimated error of that location: https://findmesar.com/p/findmepro.html

3) And how you hold the phone can be a problem. Holding it down and flat (landscape) is less accurate and your hand tends to cover the antenna. Holding it vertically (portrait) with your hand off the top of the phone will give better results.

Too much? I'm not sure what all this means in day to day use except to be careful when using these gizmos and double check to make sure the location shown is internally consistent with where you think you are. When reporting or receiving coordinates from someone, but sure to clearly give coordinate type etc.

OK. No mas. Coffee time!

g.

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Re: Using digital maps/navigation in backcountry?

Post by rlown » Mon Jun 05, 2017 11:43 am

gdurkee wrote:OK. No mas. Coffee time!

g.
Nice read on tech.. thanks.. You haven't mentioned chargers for phone users (yet.) :thumbsup:

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Re: Using digital maps/navigation in backcountry?

Post by BigMan » Sun Jun 11, 2017 10:58 am

I use paper maps and compass. I use Gaia GPS on the iPhone 6 as a last resort.

Here are the settings I use to prolong battery life:

WiFi = OFF
Bluetooth = OFF
Cellular > Cellular Data = OFF
General > Background App Refresh = OFF
Privacy > Location Services = ON, but disable all nonessential Apps (the GPS mapping App must be on, of course)
Privacy > Location Services > [at bottom] System Services > everything OFF
[note that some of these services, e.g. "Find My iPhone", cannot now be switched off without a cell connection! But it probably makes no difference if they are left on when the cell service is disabled locking the SIM, switching them off was a "belt and braces" measure ]
In wilderness lies the hope of the world.

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Re: Using digital maps/navigation in backcountry?

Post by rlown » Sun Jun 11, 2017 12:08 pm

[youtube_vid]<iframe width="854" height="480" src="https://www.youtube.com/embed/h_U4Vwawkc0" frameborder="0" allowfullscreen></iframe>[/youtube_vid]

Just saying..

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Re: Using digital maps/navigation in backcountry?

Post by rlown » Fri Nov 24, 2017 7:57 am

How did the classes work out, George? Asked Ms. ranger who tagged me for my wilderness permit what they carry. After an ok on the permit, she said "we carry a delorme and a radio."

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Re: Using digital maps/navigation in backcountry?

Post by Wandering Daisy » Fri Nov 24, 2017 9:24 am

For me, the map question is part of the more general concept of your entire "kit" of digital devices. If I were to use a lot of other digital gear and gear needing external power (PLB, phone, lighting) that would justify carrying a solar charger or lots of batteries, I would then also take a GPS. As it is, I often do not even take a head lamp, or even my little IPod player. And my 8-oz cameral can go 10 days on one small battery, takes better photos, and is lighter than my current I-phone, so I never take the phone. Until PLBs come down in cost (including the use fees) I do not use them either. Thus, paper maps for me is the overall lighter weight option, particularly if GPS users also take backup paper maps.

The other factor is familiarity with any map system. I have had a lot of training and frequent use for maps, to the point where they are second nature to me. Few younger backpackers get a chance to become really proficient in paper maps, so the GPS is probably better for them. Unlike the younger people, I can get my bearings faster by pulling out the paper map than using a GPS. Paper maps force me to be mentally, solidly aware of topography and orientation. Not that a GPS location is not useful, but a arrow pointing to "here" does not make me feel at a gut level, part of the topography. But, of course, to many, a paper map is just a maze of confusing lines. Some people also just simply do not have any aptitude to orient with paper maps. These people really NEED a GPS!

Nowadays, we have a choice. I still think it is useful for everyone to LEARN to use paper maps, but if GPS is more comfortable for them, then now there is that choice.

The third choice, that few today would even consider is the "no map" option. Native Americans, early explorers and John Muir did not use maps at all. There are skills that allow you to go out and return without maps altogether! We have to a great extent lost those skills. Again, good skills to learn even if you use maps or GPS. I have used this method, not by choice, because I simply forgot my maps and did not realize it until I got out there! It really works better than you may think.

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Re: Using digital maps/navigation in backcountry?

Post by rlown » Fri Nov 24, 2017 9:31 am

Be careful on memory. Mine blew out on the last trip.. Watched the sun rise and set, but the heart drugs interfered with my mental location. Looked at the Delorme the next day and figured out where I was. (I've been on that trail 5 times before.)

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