Accurate Trail Data Has Many Uses

By Robert Bennett,

If you've read my writing then you know my mantra: accurate geospatial data... and you might be asking yourself, "Why does it really matter?"

It is true; a paper map with a very large scale does not require highly accurate points in its depiction of trails. Take for example the older USGS 7.5 minute paper topographic maps. One quadrangle represents 49 to 70 square miles (~127 to 181 km²) of earth. These maps use a 1:24,000 scale (1 inch on the map = 24,000 inches or 2,000 feet of earth) which limits the detail of individual trails on the map and the completeness of the network of trails on the map. The 1:40,000 and 1:80,000 scale National Geographic Trails Illustrated maps have even less detail. The scale of these maps is large and constant—we expect limited accuracy on paper maps.

Accuracy with a high level of confidence is required in digital maps, such as Google Maps, Apple Maps and HERE Maps which change their scale as we zoom in and out. Take for example Google Maps which use the Mercator projection; zoom in all-the-way (scale 19) at latitude 35 and one pixel will represent approximately 0.802440 feet (0.244584 meters). The horizontal accuracy of all trails (or anything else) on a digital map at this zoom level need to be much more accurate than a paper map, especially when the digital map is displayed on a device the size of an Apple watch. But accurately depicting trails on maps is only one use of accurate points.

Multitudinous, highly accurate geographic trail data has many other uses unrelated to depicting trails on map tiles. Post-processing route data collected by wearable devices to accurately calculate energy expenditure is another use. Let's consider a few more uses of the data.

Cartographic Spam

I wrote about cartographic spam and it still exists, but with accurate points, search engines can eliminate a lot of it. We can decode the trails displayed on map apps and websites and compare their polylines with accurate points. Search engines can determine if the data in map apps and web pages is trustworthy and rank them in search results accordingly; search engines can exclude pages from search results that promulgate illegal hiking trails.

Hiking Directions

Driving directions are provided by many of the most popular map apps, but hiking directions are not as common. With accurate and up-to-date points, map apps can provide accurate time, distance and cumulative elevation gains for hiking each segment of a trail. Map apps can warn hikers when trails close, and with knowledge of a person's weight, they can also provide the caloric expenditure of hiking each segment of a trail. With accurate points, we can answer the following questions:

  1. My geographic position is (x1,y1) and my weight is 200 lbs. What is the shortest distance to (x2,y2) and how many calories will I expend hiking there, traveling 10% slower than the average hiking speed?
  2. My search radius is 5 miles, my geographic position is (x1,y1) and my weight is 180 lbs. Where can I hike in this area to expend at least 250 calories, traveling 10% faster than the average hiking speed?
  3. My search radius is 10 miles and my geographic position is (x1,y1). What are the names of the most difficult hiking trails in this area and where are they located? What are the names of the hiking trails with the greatest elevation gain in this area and where are they located?

Product Reviews

Product review spam is a problem for just about every e-commerce website. But with accurate points, knowledge of a reviewer's product purchases and where the reviewer may have used these products, we can rank some product reviews as more trustworthy than others.

Obviously, companies such as know when you purchase hiking boots, tents, poles and other outdoor equipment from them. If you also use a wearable device on a hiking trail and upload your tracks to a place that Amazon can access, then using accurate points, Amazon can profile your hiking expertise. With this knowledge, Amazon can label your product reviews (relevant to your outdoor equipment purchases with Amazon) as being more trustworthy than others. As an example, let's say you hiked 75% of the Bright Angel Trail in Grand Canyon National Park from the south rim to the Colorado River while using a (GPS tracking) wearable device. At the end of the day, you upload your tracks to a place that Amazon can access. Amazon can comare your tracks with accurate points to understand where you hiked; 75% of the Bright Angel Trail in the south-north and north-south directions. If you recently purchased hiking boots from Amazon, then Amazon can ask you, "Did you wear your new boots on the Bright Angel Trail and if so, can you please write a review about the boots?" As you hike more, Amazon can profile your activities; are you someone who regularly hikes deep in the backcountry, or someone who stays near the trailhead? Amazon can label some product reviews as having been written by a verified hiker: "Robert hiked 2,500 miles during the past year." Amazon can make the reviewer's name clickable to show people where the reviewer hiked: "Robert hiked 75% of the Bright Angel Trail during Spring 2015." Of course, not everyone will want to share their tracks with companies like Amazon, but I believe there are people who will want to use their wearable devices specifically for this purpose; many people will want to share their route data with Amazon to improve the trustworthiness of their product reviews. Imagine two boot reviews. The first boot review was written by a person named John and that's all you know about him. The second boot review was written by a person named Robert who Amazon has verified as having hiked 2,500 miles during the past year; you can see a list of all the trails Robert hiked during this time period, the percentage of each trail he hiked and the day of the year that each trail was hiked. Which reviewer would you trust more?

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