Automotive GPS devices rely on a database of internal roadmaps to provide accurate navigation data and directions from one point to another. Once the receiver determines its location in three-dimensional space, it correlates that data to the internal map to plot its current location. Maps are sometimes out of date, with updates coming only a few times a year from many manufacturers. A system such as TomTom’s Map Share helps bridge the gap between these official updates with user-supplied information.
When you purchase a GPS, street maps for your country or region are preinstalled with it. Typically, manufacturers update these maps on a quarterly basis, requiring you to purchase individual updates or a subscription if your unit doesn't include lifetime updates. While the GPS companies strive to keep their maps accurate and up-to-date, the speed of development and construction can lead to situations where the internal maps suggest routes that are unavailable or inefficient in the current situation.
The Map Share system enables GPS users to note any instance where their device’s map doesn't correspond to reality. For instance, if your GPS directs you down a street that the city has closed due to a long-term construction project, you can flag that route as unavailable, taking it out of the system’s navigation calculations. Map Share enables you to upload these changes to the system’s online database, enabling other users to download updated corrections to the map on a daily basis.
The chief advantage of Map Share is that it enables the system to correct for construction and development much more rapidly than would otherwise occur during the scheduled map updates. This can be extremely effective in regions far from population centers, which might be a low priority for official review. In addition, the sheer amount of data involved in a map database means that small errors can go unnoticed for an extended time, and a Map Share correction may save you considerable time and stress if your route happens to pass through an area where one of these mistakes exists.
The major disadvantage of Map Share is that anyone can upload a correction at any time, whether or not the route actually exists. Manufacturers stress that these corrections are not official updates to the map and enable you to customize which Map Share updates they accept. If a large number of users upload the same correction, chances are it's a legitimate update, while a correction sent by only one user could be incorrect or useless.
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