We’re always working behind the scenes to improve your AllTrails experience. One area that has been long overdue for improvement is the elevation information we provide on our website and through our mobile apps. Today, we’re excited to announce the launch of our own Elevation Service (codename “Everest”) which is rolling out across all our products.
What’s an elevation service?
As you may have noticed with your own recorded tracks, elevation readings provided by mobile phones and GPS devices are notoriously unreliable. Even though a good GPS signal can position you within 20-30 feet of accuracy, the elevation is often 2 or 3 times less precise on a mobile device. Those errors really add-up when you want you to know how many vertical feet you’ve gained or lost during an activity. The best way to overcome this is to use an elevation service to improve the accuracy of recorded GPS tracks by using the “known” (correct) height at each point.
Up until now we had been using the Google Elevation API, but as we’ve grown its limitations have become a serious problem. While generally a good service, Google has strict usage limits, it only provides a small sample of elevations (512 elevation points regardless of route length) and it fails completely for longer routes due to a length limit. We created Everest to eliminate these issues. This was no small undertaking since it required wrangling a large amount of data in order to cover the planet (nearly 1000 gigabytes) while ensuring lookups were lightning fast.
How much better is Everest at providing accurate elevations?
The following profile shows elevations recorded by an iPhone 5 / iOS7. This trail has an even grade that steadily rises from to 50m to 180m so you’d expect an elevation gain of ~130m. Using the elevation readings from the phone we calculate a total gain of 337m and a loss of 213m:
This is the same trail after its data is corrected by the Everest elevation service. Notice how the profile more closely matches the true profile of the trail which results in a much more accurate elevation gain of 128m and a loss of just 11m:
All you hardcore adventurers out there will be excited to know that Everest is built to handle even the most extreme cases. How extreme? Here is the elevation profile for the full 2,180 mile Appalachian Trail (“center line” route) which contains over 312,000 individual GPS points:
You might be wondering how much more accurate the elevation reported by Everest is than the Google Elevation API for the AT.
According to the Appalachian Trail Conservancy, hiking the entire Appalachian Trail is equivalent to scaling Everest (29,029 feet) 16 times (link). The elevation gain from the profile above (generated by Everest) calculates the total gain as 497,375’, while Google’s service only calculates 137,555’, a massive difference.
How soon can you get your hands on it?
Everest is available on AllTrails.com for all users today so you will immediately see more accurate elevation profiles and stats:
Having all this elevation data on tap also means AllTrails Pro members will have the most accurate elevation information available anywhere at their finger tips when planning routes using Map Editor:
While much of this improvement takes place for you behind the scenes, you might have already noticed an increase in speed and reliability for showing the elevation profile for longer tracks in your My Tracks list.
Over the coming weeks we will be reprocessing all recorded tracks so you’ll start to see corrected elevations and statistics being used throughout our mobile apps.
Now that we can harness the power of Everest, we have a ton of ideas of how to leverage this new service to further improve your experience on AllTrails. Do you have an idea you’d like to share? Do you have a service that could benefit from Everest? We’d love to hear from you.
- Marcus, Head of Geodata @ AllTrails