Category: Tech

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GPSMap versus smartphone

When it comes to navigating a hiking trail, compared with 10 years ago we’re spoilt for choice. Numerous smartphone applications have carved out their niche since then. Visorando, VisuGPX, SityTrails, AllTrails are just the most well-known. These mobile applications – sometimes combined with a website – are often participative, allowing individuals to use trails posted by others: a kind of social network for hiking. You can plot trails on a map background, visualize routes, search for routes by region, and so on.

Trouvadou viaduct -abandonned rail infrastructure : Euzet

Before the emergence of these applications and sites, people used dedicated GPS-type handheld devices – similar to those in cars, but designed for use in the field, with pre-packaged maps and native functions in the device’s software. The aim of this short article is to propose a comparison between smartphone use and a Garmin GPSmap for navigating in the field and finding your way around etc.

The GPS device I’m referring to is the Garmin GPSMap 66, but the observations also apply to the 62 and 64.

GPSMap versus smartphone

Which appliance to choose? This is very much a matter of taste. For long-distance routes through areas without network coverage, GPSMap will do the trick. For short outings in France, the phone will be preferable. If you’re a fan of IGN 1:25000 blue maps, you’ll want to go for the phone, because Garmin maps, while very readable, aren’t quite as “pretty”. Conversely, if you want a road companion that you can handle with just one hand, GPSMap is the way to go.

Final comment: If you don’t want to be geotagged by the tech giants and give priority to protecting your privacy, GPSMap will be your best choice.

Your view ?

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Altitude measurements

I used a Garmin GPS 64 to record altitudes during a recent hike along the the Vidourle river-mill circuit and compared the recordings to the theoretical altitudes obtained by generating the GPX with an online tool using the IGN basemaps. Here below is a comparison chart.

altitude comparisons
altitude comparisons

First, notice there is a growing lag between the peaks on the theoretical profile (green line) and the recording (red line) with the peaks on the recording occuring later then the peaks on the theoretical profile. This is normal, because we did not stick exactly to the theoretical track. At Montredon, we wandered around the site which added some distance to the recording that does not appear in the theoretical profile. (Note: We also climbed a bit higher than planned.)

However, there is still something strange going on. The recorded Garmin altitude, starting from around 3 km in, starts tracking progressively lower than the theoretical altitude. The Garmin data stabilises between 10 and 20 m altitude while in reality, no point on this circuit is below 20-25 m so the Garmin data is incorrect. Is this because the differences are within a margin of error for altitude measurements with a handheld device ? Maybe but if so, why is the tracking much closer for the first 3 km ?

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WordPress mapping plugins

Orux Maps altimetric profile vs theoreticalThis site, built with WordPress, uses a couple plug-ins for mapping. They are Leaflet Map and WP-GPX-maps.

Leaflet Map

Leaflet map allows you to display a track on a map background. The plug-in allows for use of OSM maps via MapQuest. To use MapQuest you need to sign up for an API key from their website, and for modest use like this website, the API key should be free. However, I opted not to use Mapquest. This is France and France has the IGN (Institut National de l’Information Géographique et Forestière). This institute publishes folding paper maps at many scales and the 1:25000 scale maps are outstanding for hikers. It seems that every department in the country has a hiking trail plan and these trails are all marked on the IGN maps. One point of warning though. The paper versions are sometimes out of date. Continue reading “WordPress mapping plugins”

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GPS trackers and altitude

All hikes start from the iron cross of Gattigues
Any attempt to get a good fix on cumulative climbing using GPS devices (handhelds, or smartphones) is fraught with error. Anyone who has used these GPS tracking devices knows that, while longitude and latitude are quite accurate, the altitude measurements at any given point vary from accurate to completely off the mark. GPS chip quality, embedded software and various external factors affect these readings. Walking at the base of a steep limestone cliff will cut out half of the sky and half of the satellite readings. Walking through a wet forest under wet leafy trees degrades the signals too. And there might be times when military services move the geopositioned satellites to serve a military purpose thereby degrading consumer level accuracy. So in this article, I compare a couple different apps to the Garmin GPSMap 64s to see if there are any conclusions. Continue reading “GPS trackers and altitude”