I’ve written a few projects in the past that require Latitude and Longitude to work, so when my son started learning about these amazing things we had to have a play with them!
Latitude and Longitude
These units of measurement are part of the World Geographic Coordinate System and are used the world over for many different things (primarily navigation).
They’re pretty confusing and hard to remember so lots of people have adopted the new What Three Words system as a way of remembering locations (it’s a bit easier than the long numbers you see in the image). The What Three Words system reminds me a lot of DNS (the system that translates domain names to IP addresses of servers across the internet and allows multiple websites to live on one IP address).
Joining the dots – Strava!
We’re a family of runners these days (not all of our lives but more recently we’ve headed into half marathon, 10k’s, 5k’s and Junior Parkruns) so we use Strava for tracking our achievements, but I in particular don’t track my runs in Strava, I use my Garmin watch to track me which then syncs it to Strava.
I was quick to point out to my son when he started discussing Latitude and Longitude that all Strava does is join the dots and turn it into a game.
The above image is an excerpt from my GPX file (GPS Exchange Format) from a family trip to wander around beautiful Lacock, in it we can see the Latitude and Longitude we started it and at what time, and where we were just a second later.
Strava simply plots these points on a map, joins the dots and then calculates speeds based on how far you’ve moved along these tracks in a given time – simple! It does a lot more by turning it into a game with achievements and a social network but that’s the basic premise.
In the excerpt from our little mooch you can see my watch also sent some other information in the form of my heart rate and the cadence at each time stop.
Sampling Resolution (why no wiggles?)
This discussion inevitably lead to the follow up discussion,
“Why does it not track when I wiggle in and out of bike racks on my bike?”
The answer is fairly simple!
The sample rate as you can see in this activity is every second, but based on your device and the activity you’ve told it to track your device might store the coordinates only ever 2 or 3 seconds.
So, if you perform a zig zag manoeuvre, it may only sample/store your coordinates at the top of each zig! This also accounts for when you walk with the children and they’re zig-zagging all over the path, your route looks far smoother than that!
What can you do with this?
There’s lots of things you can do and I’ve built a few projects that use this system. One of my favourites is the Race to The Stones tracker I built for some friends when they were running an ultra in 2019.