Best Source For TOTAL Elevation Information?

[robow8]

https://awhite4777.pythonanywhere.com/S ... ault/start

[Wandering Daisy]

When you say "for a hike", I interpret that as a day-hike, not a backpack. Knowing the elevation gain for a day's travel is quite important! It helps to estimate the time it will take to travel from A to B. I calculate elevation gains (daily) in all my trip planning. I have the old TOPO software. Nothing wrong with the good old "count contours" method either.

As for total elevation gain for a 10-day backpack trip, knowing that is just interesting. It is the daily gain that is useful.

The older I get and the more my knees hurt going downhill, the more I also pay attention to elevation loss. I simply will not drop more than 4000 feet in a day unless it is an emergency. I still will occasionally go up 6000 feet in a day. My joints just complains less if I keep both under 3000 a day. This is why I calculate both gain and loss each day when planning a trip.

Most guidebooks state the elevation gain for specific hikes. People also post their GPS tracks on the internet. I would "google" the route (if it has a name) and see what you get.

[rlown]

a bit off topic, but I tend to love downhill more than uphill. guess my knees are somewhat intact. My speed actually increases significantly for downhill, unless it really loose or VW sized talus. But I agree, total isn't that important as is your up and down for the next day's trip.

[wildhiker]

Here's a caveat about calculating elevation gain/loss with mapping software (Google, CalTopo, etc). These programs are combining the lat/long (horizontal) coordinates of the trace of the trail with vertical data from the digital elevation model that is based on a rectangular grid - usually a datum point every 30 meters. Thus, depending on how exactly - and correctly - the trail is drawn, there can be a lot of "noise" introduced where the trail is interpreted as crossing back and forth over a contour line even when it is not, thus inflating the elevation gain/loss. Conversely, some elevation gain/loss can be missed because the vertical data points are only every 30 meters. In my experience, having too many waypoints on the trail track leads to a lot of extra noise that inflates the elevation gain/loss values. In CalTopo, at least, paid subscribers can modify the sampling of the track for the elevation profile to increase the horizontal difference between points and thus reduce the noise.

-Phil

[Hobbes]

I like to keep track of elevation gain/loss by section, day and trip (+- contour counting). Basically, it comes down to logistics, which is true for any kind of travel, backpacking or otherwise. That is, the further you are from home, the longer the trip, along with greater unknowns, requires more planning and preparation.

For example, compare going to a local golf course vs traveling 350 miles out of town. Does it really matter if your tee time is changed or there's some other change in plans? By analogy, if you're going to the Sierra to base camp or simply wander around doing low daily mileage, then it's not that critical to breakdown the hike into great detail.

However, if you're shuttling cars between fairly distant THs, you have ambitious daily mileage goals, and you're tackling known difficult sections of the range, then you'll probably be interested in trying to determine what exactly you've signed up for. Add to that equation a (strong) hiking buddy or two, and now you've essentially committed to a fairly significant obligation.

This is where trip planning becomes crucial, not just daily mileage, but expected difficulty & energy requirements: terrain contour + elevation gain & loss. It also ties into water carries, food weight, time of day, etc. And don't forget the importance of morale - imagine having a big (section) climb after lunch in the heat of the day. If you know beforehand what's expected, then you can either plan around it, or simply get into a proper mental state to "suck it up" because that's just the way it is.

Keeping track (records) of section, daily & total elevation gain/loss along with mileage numbers also helps towards having reasonable expectations for future trips. Assuming you're essentially in the same condition in following years, you'll have more confidence planning trips, rather than getting surprised and blown out of the water. IOW, having to bail out, becoming discouraged, etc.

So, IMO it's better to know & understand your limits and incorporate them into realistic goals; you can't do that unless you know what's in store. Here's an example of the records I kept for a hike last year (grey scale indicates elevation gain):

https://docs.google.com/spreadsheets/d/ ... edit#gid=0

[longri]

As Hobbes said, it's just like knowing the mileage or the fact that there's a big talus field or a river crossing or whatever. The difference between 2000 feet of total gain and 5000 feet is more than just a number.

But often it is just that. Many of us love our numbers, our statistics, our spreadsheets and charts so much that they can be an end in themselves. We wear special watches and carry fancy gadgets and enter the data into software programs to generate reports which we then post on the internet to share with other lovers of data.

(BTW, cool spreadsheet, Hobbes. How did you obtain those numbers?)

Walking the JMT one year I stopped hundreds of times at specific locations and wrote down the time, place, temperature, reported elevation and reported total elevation displayed by each of two altitude watches I was carrying. When I got back I spent hours playing with the data in order to arrive at an estimate of the total elevation gain for the JMT (it wasn't 47,000). The next year I walked the JMT again, that time with a small box of home brewed electronics that combined dual altimeters, a GPS, LED screen and SD card. I recorded data for every second of the walk, not counting sleeping or long breaks. I returned home with hundreds of thousands of data to process!

I already knew what the JMT was like.

[rlown]

There are aLOT of kmz files out there for the JMT such as at: http://www.trailjournals.com/tzrecked/
Others were listed in the google search results..

[longri]

You can push raw GPS data through an online app (GPS Visualizer) to get profiles and total gain. But using GPS data alone to obtain elevation can be very inaccurate at times. It still relies on a digital map model and a sometimes poor trace of the trail/route (because of location jitter). Such data have to be "massaged" thoroughly or else you get nonsense results.

Better GPS devices include a barometer to somewhat mitigate those errors real time.

NASA has been measuring our snow pack in recent years using airborne LIDAR (cool website). They can measure elevation to within 10cm. They're using these data to determine snow depth by comparing it to summer elevation measurements. But that same technique could be used to very accurately calculate trail/route profiles. Super geek potential there but I doubt NASA would be interested.

[dave54]

Here's a caveat about calculating elevation gain/loss with mapping software (Google, CalTopo, etc). These programs are combining the lat/long (horizontal) coordinates of the trace of the trail with vertical data from the digital elevation model that is based on a rectangular grid - usually a datum point every 30 meters. Thus, depending on how exactly - and correctly - the trail is drawn, there can be a lot of "noise" introduced where the trail is interpreted as crossing back and forth over a contour line even when it is not, thus inflating the elevation gain/loss. Conversely, some elevation gain/loss can be missed because the vertical data points are only every 30 meters. In my experience, having too many waypoints on the trail track leads to a lot of extra noise that inflates the elevation gain/loss values. In CalTopo, at least, paid subscribers can modify the sampling of the track for the elevation profile to increase the horizontal difference between points and thus reduce the noise.

-Phil

I remember working with 1 meter DEM files. A real PITA. Real good data but the files were huge and processing even the simplest function took a lot of time when doing an entire watershed analysis. Unless a high degree of precision was necessary I usually resampled to 5 or 10 meters.

[Hobbes]

Cool spreadsheet, Hobbes. How did you obtain those numbers?

You mean elapsed times? By training like a mofo.

Oh, you mean distances & elevation? The PCT/JMT sections are easy (you can see the way-point column). There have been many detailed mapping projects, with perhaps the most important being one conducted by Half-Mile:

https://www.pctmap.net/

Non PCT/JMT sections are derived by getting out my trusty calipers and measuring 1/2 mile increments. You know, like the itsy-bitsy spider. Same too with elevation gain/loss: simply add/subtract contour lines.

Whether the mileage distances and/or elevation gains/losses are accurate isn't necessarily that important (as it pertains to me) as long as I have a consistent history. That assumes, of course, that I use the same basic techniques for measuring & evaluating different hikes. Since I think I do, and because I keep track of my actual time for each major section noted, then at least I'm comparing apples to apples (for myself).

In my particular case, what I'm personally shooting for is a good understanding of what I'm getting myself into. I tend to plan fairly ambitious goals over compressed time periods (exactly opposite of my brother, who likes to wander according to whim). So far, I've lucked out and haven't had a situation develop where I've gotten into trouble. Knock on wood and all that ...