1/10/2024 0 Comments Measure distance google mapsThis error is the largest at the lowest zoom levels (low meaning, further out where you can see most the planet). There is some amount of rounding error when mapping tile pixels to the screen. There's two possible ways errors can creep in: Every time you zoom in, each tile is split into 4 sections that are represented by new tiles. Depending on the area of the map they both have up to 19 or so levels of zoom. Google/Bing maps work by presenting you with a grid of 256x256 pixel tiles that they align to an internal coordinate system. Also, even with perfect reception of GPS satellites, your GPS can be off by up to 12 meters (or less, depending on what latitude you live at), so that can add to the distance error of your run. If you plot a route on a road and there is a turn, does it run the path to the center of the intersection and then turn a sharp 90%? Or does it bend the path in a curve around the turn? Either way, if you are running and you aren't in the street, chances are you aren't taking the path that it is using to calculate the distance.Īs I said in the short answer, GPS accuracy around sharp curves can be low because GPS is just measuring distance between points on a long list of points that it collects over the course of your run, so if you run around a corner, the GPS could cut the corner off, making your route seem shorter than it is. What I do not know is how Google calculates distance around curves. Either way, you can assume the maps are distance-accurate within less than 1% and be safe. Google uses a Mercator Projection to map a spherical globe surface onto a flat map, so as the map gets further from the equator, distances get a little wonky, however, I'm sure that Google corrects for this in their distance algorithms. This means that when you are looking down at the map and measure with a ruler the map is pretty accurate (spent a little time looking around for accuracy data, but all was anecdotal). Google maps is accurate for 'as the crow flies' distance. However, if you use the route mapping tool, it does not calculate exactly the path you are taking when you turn, so small distance discrepancies over many turns add up.Īlso, iPhone GPS is not all that accurate around turns either, so it could be a combination of the two. If you're running in a straight line, Google is super accurate (no stats for you, sorry).
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