The accuracy of the routes displayed on my maps depends on if they:
1. were recorded by a GPS capable device – most trips since about 2012.
I have used hand-held GPS units (eTrex & eTrex 30, Suunto watch, Garmin fenix 3 & an iPhone 6+). The Garmin watch is my current preferred method as it is by far the most energy efficient and also keeps an eye on how hard I’m working!
Some of these recordings are incomplete, as I have been known to forget to start or finish logging and occasionally pause the device for too long (pauses can show up as straight line sections).
The Garmin watch syncs automatically to the Garmin Connect website from where I can download the routes as .gpx files before using them in this website.
2. have been reconstructed from memory.
To do this I have to trace out, as best I can recall, the most likely route using the 1:25,000 scale topographic maps within Memory Map Topo (for Australian and New Zealand trips). Altitude data is then added using the online GPS Visualizer conversion program.
The accuracy of Records
Accurate GPS altitude records are difficult to obtain with handheld consumer grade GPS units, especially when moving through deep valleys or under heavy trees cover. For this reason all ascent and descent data on this site can only provide an approximation of the reality.
To illustrate this issue I have compared the results from my GPS unit with NASA’s SRTM3 Digital Elevation Model dataset. The two records below are of the same trip recorded by a Garmin Fenix 3. The upper is constructed from data recorded by the Garmin device. The lower has altitude data overwritten by online GPS Visualizer conversion program from a Digital Elevation Model database. As this data set only has a resolution of 90m, it also is only an approximation. This is clearly evident in the NASA dataset as Mount Townsend has an official altitude of 2209m yet clearly displays below 2200m.
Note the differences in total climbing and total descent between the two.
Garmin Fenix 3 data
Max elevation: 2217 m
Total climbing: 1249 m
Total descent: -1252 m
Average speed: 7.13 km/h
Total time: 08:08:40
Garmin Fenix 3 altitude data replace by NASA’s SRTM3 Digital Elevation Model dataset
Max elevation: 2182 m
Total climbing: 1056 m
Total descent: -1057 m
Average speed: 7.15 km/h
Total time: 08:08:40
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Well I truly enjoyed reading it. This information provided by you is very useful for proper planning.