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  1. #1
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    ? the "shift" for China maps

    How is the shift done and can it be done for any map? I would like to try it on some maps that i know to be way off. My road tracks lay on top of each other, but they are not on top of the road lines on the gps display.

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  3. #2
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    Quote Originally Posted by jpooh View Post
    How is the shift done and can it be done for any map? I would like to try it on some maps that i know to be way off. My road tracks lay on top of each other, but they are not on top of the road lines on the gps display.
    For China maps, the shift is added when the maps are compiled. It cannot be done on any map as you need the source files of that map to compile.

    If your tracks were recorded in China with WGS84 coordinates, then you can show them correctly with the Venus shift-corrected China maps, available in this forum.

  4. #3
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    okay, thanks. This wouldn't be for the china maps at all, but i was just wondering how because it would be nice to see some accuracy on some products i know are showing something wrong. either the tracks are off (all the time and only there) or the maps are and i would like to think it's the maps.

  5. #4
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    I suspect your particular problem with tracks not overlaying the roads may be more to do with the general inaccuracy of the road positions on the map as well as the somewhat imprecise positioning of the GPS device itself [3 meters/10 feet is as good as it gets and 15m/50ft is barely acceptable for vehicle guidance]. The roads shown on a City Navigator map for instance may not line up with the actual physical roads but the 'lock on road'/'snap to road' software function will show the vehicle's screen position as being on the closest likely road. This compensates for both the inaccuracy of the device itself and the 'near enough is good enough' attitude by map makers to the location of the roads on their maps. In [Only registered and activated users can see links. ] you can see the actual tracks recorded by several devices when overlaid on a satellite image. Some serious deviations are shown by some devices.
    'Thanking Posts' are banned. To thank someone, and/or to see hidden links and content, use the [Only registered and activated users can see links. ] button below left of the helpful post then refresh your browser [F5 key]. 'Thanking Posts' are banned.
    Please don't spam. Posts serving no purpose other than to thank or to ask about hidden links are trashed or deleted, it's GPSPower's policy. Please don't spam.
    [Only registered and activated users can see links. ] should make their first post as a new Intro Thread in [Only registered and activated users can see links. ].

 

 

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