Blame the Mercator projection
Working on a simple way to display the route for my runs in workout log. To avoid map dependencies (and as a small privacy measure) I'll be displaying a simple SVG showing the activity route based on the GPS waypoints.
The route was looking right, but the aspect ratio was all wrong. As always, the blame lies with the Mercator projection. Or, in this case, the opposite: I wasn't applying any corrections based on latitude. At 60°N that results in some serious distortion.
Here's a screenshot showing the difference between no Mercator projection at the bottom and the more "correct" version with the Mercator projection applied at the top:
You learn a surprising number of things trying to set up your own workout log!