At the turn of the century, the premise was that GPS was revolutionary, would work everywhere we needed it, and everything else was old hat. Turns out that we need something that works indoors and in critical outdoor applications without a clear view of the sky, like downtown cores, dense forests, and in-and-out of coverage places like mountain valleys. A Canadian team out of Calgary obtained a couple of key patents and founded a business around navigating with sensors when GPS/GNSS was obscured or just plain not available. Just coincidentally, around the same time, cell-phone and tablet manufacturers were adding these same sensors to their devices so users could readily re-orient screens and play motion video games.