Quote from S.:
How would you draw "100 meter wide circles" on a map that doesn't have a scale and if it would, it would've probably been incorrect?
By doing it on the 6k×6k aerial map available at myepsilon.org which is on scale (1 pixel = 1 meter) and also translates nicely to the game's internal coordinates (top left is -3000,+3000). I've also stretched and cropped the game map to those dimensions, but of course you can work out and use its original scale if you want.
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Correction to the description of the video from the last post: Putting the bike in the garage at the end isn't needed for SS after all. You just need to be driving it when you enter the marker, because otherwise it despawns. I thought I'd tried that but I tried it again and it's fine.