{"id":2666,"date":"2016-01-19T19:59:43","date_gmt":"2016-01-19T10:59:43","guid":{"rendered":"https:\/\/regex.info\/blog\/2016-01-19\/2666"},"modified":"2016-01-19T19:59:43","modified_gmt":"2016-01-19T10:59:43","slug":"more-details-on-the-insidious-ios-snap-to-road-feature","status":"publish","type":"post","link":"https:\/\/regex.info\/blog\/2016-01-19\/2666","title":{"rendered":"More Details on the Insidious iOS Snap-to-Road “Feature”"},"content":{"rendered":"\n\n
\n\nMore iPhone Location-Track Testing<\/span>\n<\/div>\n\n

This post is a short followup to last month's “<\/span>The Scourge (or\nBeauty) of \u201cSnap To Road\u201d with iPhone Location-Tracking Apps<\/a>”<\/span>, in which I explained<\/span> how an attempt by Apple to make the iPhone\nlocation services more relevant for car navigation can end up destroying the accuracy for other uses such as geoencoding or\nfitness tracking. When enabled, the user's location is “<\/span>snapped”<\/span> to the center of the nearest road; internally Apple calls\nit “<\/span>Map Matching”<\/span>; I call<\/span> it “<\/span>Snap to Road”<\/span>.<\/p>\n\n\n

In the screenshot of Google Earth seen above, the red line, recorded with the “<\/span>Snap to Road”<\/span> feature disabled, mostly matches up with my green-line actual path (which I drew<\/span> on the map by hand from\nmemory), but the cyan line, recorded with “<\/span>Snap to Road”<\/span> enabled, is\nridiculously devoid of detail... it makes it appear as if I was<\/span> walking down the exact center of each\nroad; you can't see what side of the road I was<\/span> on, nor even that there are turns at the edges.<\/p>\n\n

Unfortunately, this iOS feature can not simply be enabled or disabled by the user or the app developer — Apple, in its\ninfinite wisdom, chooses when it goes on and off and does not share any details (or even confirm that it happens!) — so\nI wanted<\/span> to do more testing to understand when it does or doesn't become enabled.<\/p>\n\n

Evgen Bodunov, the developer of the most-excellent\nGalileo Offline Maps<\/strike> (Name changed Feb 2019 to Guru Maps<\/a>), kindly made a special<\/span> version of his app\nfor me which allowed me to explicitly choose the iOS CoreLocation service\n“<\/span>Activity Type<\/a>”<\/span>.\nI did<\/span> a bunch<\/span> of riding around<\/a> with the phone set to\nvarious situations, and came up with a few<\/span> more details...<\/p>\n\n