[closed] The China offset

[chuser]

I always used OfflineMaps and it worked great. I mapped all of the local canals with my boat, noting all the points of interest. The canals are a maze, so a map is very useful. The usual GPS apps are worthless, all you can do is drop a star and they think you're trying to take roads. I use a ton of the icons and I even took photos of many places.

I didn't use my boat for a while, and when I checked OfflineMaps again, it had the "China offset". This usually only affects Google Maps, but I haven't used that in years. My phone uses BeiDou for positioning anyway. This means the displayed position on the map is wrong, offset by a predictable distance north and west.

I was planning to downgrade to a version of OfflineMaps that still used the old correct method, but decided I had better back up my map first, as it took me two years to create. Every invisible underwater rock is mapped, and I found them all by denting my propeller over and over. However, in /datastore there is nothing in the /maps directory. This makes me uneasy.

However, I did notice a cn_offset.dat in /datastore and wonder if the problem can be fixed with this file.

[Psyberia-Support]

Hi,
The application has the ability to correct the offsets on some maps over China for a while.
If you're not happy with it, you can simply turn it off: display a map that has an offset (like Google Maps), move the map view over China, tap the "Maps menu" -> "Options" -> Un-check "Correct offsets over China".

[chuser]

I figured out a workaround. The software still gives me an erroneous location when using Amap. But I can select Satellite, and then return to Amap and the position will display correctly. It goes back to the erroneous location every time the screen turns off.

[Psyberia-Support]

Amap is a Chinese map so it does have the offset.
You should be able to align it correctly using the setting given above...