I just joined this forum in hopes that someone can point me in the right direction to resolve the following problem.
I just purchased a Garmin 205W along with Garmin's City Map China since I live and work in China and do a lot of driving in this country.
To state things simply, I have been pleasantly surprised at how much information is on this map since China is somewhat secretive about some of their rural areas.
However, after using the map for about a week I have discovered the following problem.
No matter where I am in China my location as shown on the GPS screen is (my true location) is always 400 +- meters to the North of the location where I should be and 400 +- meters to the West of where I should be.
In other words if I am driving on a main highway, the map clearly shows the highway but my car symbol is shown 400 +- meters to the North of the highway or to the West of the highway depending on which direction I am going.
I was wondering if there is a way to copy the City Navigator China map from Garmin to the computer and actually shift the whole thing and reload it to the unit? I know that is a very simplified version of what needs to be done if it is possible, but if someone would steer me in the right direction to get the software and learn the process I would deeply appreciate it.
Oh.. Garmin tells me that I should tell them each and every error I find... of course all I have to do is turn the unit on and it's in error since the entire map is about 400 X 400 meters off location.
You'll have to import the data into Map Maker Pro and then you can shift the coordinates using Utilities > Vector Utilities > Actions > Transformations > Shift Coordinates of Vectors. See Chapter 9 in the manual. I guess before you start you'll need to make sure that the data is in a format that Map Maker Pro can import and that it can export your data into something that is useful to you.
This is an inexpensive Nuvi so the first option of verifying the datum settings, usually the first suspect given a consistent error, probably isn't possible.
Garmin wants to prevent its customers from either manipulating their maps or making their own for their units. Their are tools for these, based on (very welcome) reverse engineering but not for the casual user.
The issue of the China offset has been discussed in Garmin forums and Google your friend.
Map Maker has all the tools to make coordinate adjustments to raster and vector based maps but unfortunately Garmin doesn't want you to do that with their maps.